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Abstract

Nutrition is a known, powerful determinant of perinatal health and one that is increasingly recognized to have further reaching effects than previously understood. It is well known that healthy nutrition during the peripartum period can prevent birth defects in the neonate. New research suggests that peripartum nutrition may also modulate the risk of chronic disease in later life. Proper nutrition and weight gain during pregnancy also have maternal benefits including lowered risks of pregnancy related disorders. Good peripartum nutrition is a potential tool to impact the rising prevalence of obesity and related health disorders. This article will review nutrition guidance in pregnancy including macro and micronutrient recommendations, newer recommendations for appropriate weight gain based upon body mass index categories, and avoidance of potentially harmful substances. Current topics will also be discussed including fetal origins of adult disease, pregnancy after weight loss surgery, environmental bisphosphonates, and glycemic index diets.

Keywords

pregnancy weight gain fetal origins of adult disease obesity exercise bisphenol A (BPA)bariatric surgery

‘Proper nutrition can prevent birth defects and allow neonates to start life at a healthy weight, reducing later risks of disease.’

Introduction

Nutrition in pregnancy is important for maternal and neonatal health, and it is an investment in the future health for both later in life. Proper nutrition can prevent birth defects and allow neonates to start life at a healthy weight, reducing later risks of disease. Maternal benefits of a healthy diet and weight gain include lowering the risks of pregnancy related disorders, reducing the likelihood of cesarean delivery, and allowing women a greater chance of regaining a healthy weight. Topics such as the fetal origins of adult disease, pregnancy after weight loss surgery, and glycemic index diets are also current in the dialogue surrounding nutrition in pregnancy.

Brief History of Dietary Recommendations in the United States

The 1990 Institute of Medicine report and recommendations for weight gain during pregnancy were designed to minimize premature births and small-for-gestational-age infants.¹ In the years since the publication of the 1990 guidelines, the surge in obesity prevalence and concerns for the long-term health implications of high gestational weight gain, as well as new research on the peripartum risks to mother and fetus attributed to obesity, led to reconsideration of the previous guidelines. The revised guidelines take into account the health and weight of both the mother and the fetus, so that the needs of both can be balanced, and include a new category for obese women.¹

Current Recommendations

The 2009 Institute of Medicine report differs in several ways from its predecessor. The newer guidelines are based on World Health Organization body mass index (BMI) categories and now include a category for obesity for whom less gestational weight gain is now recommended. Based on prepregnancy BMI, underweight women (<18.5 kg/m²) should gain 28 to 40 lbs, about 1 lb a week in the second and third trimester, assuming a 1.1- to 4.4-lb weight gain in the first trimester. Normal weight women (18.5-24.9 kg/m²) should gain 25 to 35 lbs, again about 1 lb a week in the second and third trimester. Overweight women (25.0-29.9 kg/m²) should gain 15 to 25 lbs with about 0.6 lb a week gain in the second and third trimester. Obese women (≥30.0 kg/m²) should gain 11 to 20 lbs, with about 0.5 lb a week gain in the second and third trimester.¹

Obesity

No discussion of nutrition in pregnancy is complete without addressing the most important public health problem facing the United States today: obesity. The surge in the prevalence of obesity in the past 30 years is enormous and has important consequences for the health care system and society in general. Two thirds of US adults are now categorized as overweight or obese.^2,3

One third of reproductive-age women are obese.¹ During pregnancy, these women are at a higher risk for spontaneous abortion, gestational hypertension, preeclampsia, gestational diabetes, macrosomia, and cesarean delivery than their normal-weight counterparts. Obesity can complicate fetal surveillance antenatally and intrapartum by making it difficult to perform ultrasounds, monitor fetal heart rate, and monitor contractions. Furthermore, the risk of cesarean delivery is higher for obese women, who tend to have longer operating times, higher blood loss, more wound infections, more endometritits, and more anesthesia-related complications.⁴

The initial intervention for the overweight or obese pregnant patient is provider counseling on exercise and dietary modification. According to 433 respondents of a survey of practicing members of the American College of Obstetricians and Gynecologists (ACOG), 63.4% use prepregnancy BMI to tailor their weight gain recommendations.⁵ Monitored exercise programs have had some success in moderating gestational weight gain for the overweight.⁶ A review of antenatal dietary modifications suggested they may reduce gestational weight gain without impacting neonatal birth weights.⁷ One review of the literature notes that antenatal lifestyle changes may reduce the weight gained during gestation and identified a trend toward reduced gestational diabetes, but was not able to identify a difference in other negative outcomes. The authors identify a lack of high-quality evidence on this subject.⁸ The Institute of Medicine report “Weight Gain During Pregnancy: Reexamining the Guidelines” recommends preconceptual, antenatal, and postpartum counseling on diet and physical activity to help achieve the recommended weight gain goals.¹ One study noted that excessive gestational weight gain among women with normal prepregnancy BMIs did not increase fetal growth or prolong gestation, and mothers had a greater postpartum BMI and higher levels of subcutaneous fat when compared with those with normal weight gain.⁹

Glycemic Index

A current interest in nutrition research is the idea of the glycemic index, which can be conceptualized as the rate at which carbohydrate can be digested into glucose and then released into the blood stream. Research in this area has recently been applied to pregnancy. One systematic literature review described studies suggesting a low glycemic index diet during pregnancy may decrease large-for-gestational-age birth weights among healthy pregnancies.¹⁰ Low glycemic index diets may be most helpful for patients with gestational diabetes by lowering insulin requirements without causing fetal harm, but more data are needed before recommendations can be made.¹⁰ A Cochrane review came to a similar conclusion: Low glycemic index diets may have potential in managing and preventing poor outcomes associated with gestational diabetes, but more trials are needed to establish parameters.¹¹

Postpartum Weight Loss

Retained weight can increase a woman’s risk for chronic diseases such as type 2 diabetes and also increase the chance of entering a subsequent pregnancy at a higher prepregnancy BMI with its attendant risks.¹ Several studies have demonstrated the connection between gestational weight gain above the recommended levels and increased postpartum weight retention.^1,12 A longitudinal study from Stockholm observed that total weight gain during pregnancy was related to amount of weight gain during the first trimester. Women reporting previous weight cycling and those who reported increased desire for sugary food had slightly higher weight gains during pregnancy. Regular breakfast and lunch habits are associated with returning to prepregnancy weight.¹³

Ethnic and socioeconomic variations may exist in the patterns of postpartum weight retention. A study of 461 low-income, nonobese women that measured fasting insulin levels at entry to prenatal care found that those in the highest quartile had significantly higher gestational weight gain and postpartum weight retention.¹⁴ A longitudinal study of 427 low-income minority women found that 62% exceeded the weight gain recommendations for their BMI. Fifty-two percent retained greater than 10 pounds 1 year postpartum, suggesting the need for better counseling and interventions in these groups.¹⁵

Breastfeeding

There are conflicting data regarding the association of breastfeeding with postpartum weight loss. Although frequently touted as a method to lose weight postpartum, the association of breastfeeding with postpartum weight loss may be weak. Data from the World Health Organization Multicentre Growth Reference Study showed that duration and intensity of breastfeeding explained little of the variation in postpartum weight changes observed in different women.¹⁶ Additionally, a longitudinal cohort from Stockholm did not find breastfeeding to have a large impact on return to pre-pregnancy weight.¹³ However, in a longitudinal US study of low-income minority mothers, breastfeeding was associated with postpartum weight loss.¹⁵

Fetal Origins of Adult Disease

A growing body of evidence supports the theory that the intrauterine environment, of which nutrition is an important part, has a potentially larger role in an individual’s future health profile than previously understood.^17,18 This theory has continued to evolve since epidemiological observations revealed that small-for-gestational-age infants had increased risk of heart disease as adults.¹⁹ Prenatal exposure to the Dutch Famine of 1944-1945 was associated with impaired glucose tolerance in adults, suggesting that epigenetic changes triggered by the nutritional environment in utero continue to affect metabolism later in life.^19,20 Further research has demonstrated that a nutritionally restricted intrauterine environment may increase the risk of coronary artery disease, type 2 diabetes, and hyperlipidemia.¹⁸ Study in this area continues, but the fetal origins of adult disease theory suggests that intrauterine nutrition has an even greater role in the long-term health of the fetus that previously suspected.

Food-Borne Illnesses and Pathogens

Mercury

Mercury has the potential to cause fetal damage as a neurotoxin. Although there are multiple ways for humans to be exposed to mercury, the most common way is through consumption of seafood. Mercury enters local ecosystems, most often as a result of industrial pollution, is consumed by smaller animals and fish, and is then concentrated in larger predator fish higher in the food chain.²¹ For this reason, the US Department of Agriculture (USDA) recommends against pregnant women eating shark, swordfish, king mackerel, or tilefish, all of which are large predator fish. Additionally, the USDA recommends eating 12 ounces (approximately 2 meals) per week of fish and shellfish that contain lower levels of mercury such as shrimp, canned light tuna, salmon, pollock, and catfish. White or albacore tuna has slightly more mercury, and so should only be eaten once a week. Regarding the safety of fish caught in local lakes, rivers, and coastal areas, the USDA recommends checking local advisories. In the absence of information, only 1 serving per week of these should be eaten.²² Concern about the level of mercury in seafood may lead some women to avoid it altogether; however, consumption of seafood has clear and demonstrable benefits for the fetus, so clear messaging is important so that women do not avoid consuming seafood. For example, analysis of the Seychelles Child Development Study found that children with higher levels of methylmercury prenatally, suggesting higher seafood intakes, had better scores in some areas of neurocognitive and behavioral testing at age 17 years.²³ Warnings about the risk of mercury need to be carefully balanced with counseling regarding the benefits of a diet that includes seafood.²³

Toxoplasmosis

Toxoplasmosis is an illness caused by the parasite Toxoplasma gondii. Primary infections during pregnancy can cause morbidity through vertical transmission to the fetus resulting in blindness, epilepsy, and mental disability. Risk of contracting the infection during pregnancy can be reduced by cooking all meat to safe temperatures per USDA guidelines, washing fruits and vegetables thoroughly, hand washing by pregnant women and those around them, and cleaning all food preparation surfaces carefully. The organism can spend part of its life cycle in cats, and pregnant women should therefore avoid getting a new cat during pregnancy and minimize exposure to strays. Additional measures for women who have cats are to keep them indoors, have someone else change the litter box daily, and avoid feeding them raw meat.²⁴ Toxoplasmosis can also be contracted from environmental sources, so women should avoid drinking untreated water and contacting soil or sand unless wearing gloves.

Food-Borne Illness

Listeria monocytogenes is a bacterium found in water, soil, animals, and humans that causes a food borne illness characterized by flu-like and gastrointestinal symptoms. Listeria can contaminate undercooked meats (beef, pork, lamb), processed/deli meats, cold cooked chicken, raw seafood, soft cheeses, raw vegetables and fruits, and unpasteurized dairy products. In the United States, about 1600 people are affected by listeriosis annually. It primarily affects pregnant women, who are approximately 13 times more likely to be affected than the general population, though it also affects immunosuppressed individuals and the elderly. In pregnancy, it can result in miscarriage, premature delivery, neonatal infection, and even death. Listeria is killed by cooking and by pasteurization. Safe food handling practices are an important part of preventing listeria infections. Food preparation surfaces should be washed with soap and warm water to avoid cross-contamination. Avoid processed meats such as deli cuts and hot dogs unless heated to steaming. Be careful that juices from these products do not contaminate other foods nearby. Wash all produce. Also avoid unpasteurized dairy products and soft cheeses made from unpasteurized milk.²⁵

Salmonella is another type of bacteria causing food borne illness, usually associated with fever, diarrhea and abdominal pain.²⁶ Salmonella is commonly thought of contaminating eggs and poultry, but can be found in fruits, vegetables, and in prepared and frozen foods as well.²⁷ Additionally, salmonella can be contracted from contact with reptiles, birds, or baby chicks.²⁸ In pregnancy, it can cause potentially severe complications, including intrauterine fetal death and sepsis.²⁹ Excellent hand hygiene and safe food preparation techniques can help prevent infection with salmonella.²⁸

Environmental Estrogens/Bisphenol A

Environmental endocrine disrupters are defined as chemicals with agonist or antagonist actions at in vivo endocrine targets such as estrogen, thyroid, and androgen receptors.³⁰ An enormous amount of attention has been placed on these compounds recently in popular, medical, and government sources, especially for bisphenol A (BPA), which is used in the production of plastic. Nearly 100 tons of BPA are released into the atmosphere yearly. BPA can be found in plastic food containers like water bottles and plastic cling films as well as in resins covering metal food cans. BPA is a xenoestrogen, which is a substance that imitates the action of estrogen and may have weak thyroid hormone antagonist properties as well.³⁰ Data from the National Health and Nutrition Examination Survey suggest that more than 90% of the general US population has detectable BPA in urine samples.³¹ The end effects of this exposure are unclear. Some studies note an association between BPA and childhood obesity³² and adult cardiovascular disease and type 2 diabetes mellitus.³³ A 2011 study in the journal Pediatrics associated increasing amounts of BPA in maternal and infant urine with more anxious and depressed behavior and poorer emotional control as measured by validated scales among girls at 3 years of age.³⁴ A recent review also noted studies that claimed behavioral abnormalities among girls exposed to BPA and also earlier breast development.³⁵ These studies are suggestive, but more research needs to be done to determine the true epidemiological impact of BPA. There is a growing body of early data on BPA exposure and adverse outcomes in animals and in humans, so some pregnant women may desire to limit exposure. The compound is ubiquitous, however, making it difficult to avoid.^36,37

Supplements/Micronutrients

Folic Acid

Adequate levels of folic acid intake in pregnancy decrease the occurrence of neural tube defects such as spina bifida. The United States Preventive Service Task Force recommends that all women of childbearing capability consume 0.4 to 0.8mg folate daily to decrease the incidence of these defects. ACOG recommends supplementation of 4 mg per day for women with a prior history of pregnancies affected by neural tube defects. Those taking antiepileptic drugs may also need higher levels of folic acid.³⁸

Iron

Iron deficiency is one of the most common micronutrient deficiencies and is especially common in pregnant women. Insufficient iron levels are associated with preterm delivery and low birth weight infants. The Centers for Disease Control and Prevention recommends screening all pregnant women for anemia at the first prenatal visit and encouraging iron supplementation as well as an iron-rich diet.³⁹

Vitamin D

Vitamin D is a fat-soluble vitamin found naturally in fish, fish oils, egg yolks, and is fortified in grains and dairy products. The skin, in response to sunlight, produces vitamin D. It is recommended that pregnant women supplement their diet with 600 IU of vitamin D daily, and most prenatal vitamins contain this amount. Vitamin D deficiency is more common in those with darker skin who cannot produce vitamin D as well as in some vegetarians who do not consume any animal products. It is also seen in individuals with diseases that can result in malabsorption such as with Crohn’s disease, celiac disease, and cystic fibrosis. Finally, those with limited exposure to sunlight and obese individuals can be at risk for deficiencies, since vitamin D is extracted from the blood by fat cells.

Severe maternal vitamin D deficiency is associated with skeletal disease in the neonate. ACOG states that there is currently no evidence to support routine screening for vitamin D deficiency in pregnancy.⁴⁰ However, practitioners may elect to test based on clinical indicators.⁴⁰ Vitamin D deficiency and its impact on areas beyond bone health, including polycystic ovarian syndrome and type 1 diabetes, is a subject of current research interest.^41,42 Prospective randomized trials are needed to clarify the role of vitamin D in the prevention of preterm birth or preeclampsia.⁴⁰ There is a correlation between vitamin D deficiency and obesity.⁴³ Furthermore, some studies suggest that supplementing with vitamin D may improve insulin resistance profiles in gestational diabetes.⁴⁴

Iodine

Pregnant women are recommended to receive 220 µg of iodine daily and lactating women 290 µg daily for the neurocognitive benefit of their children. Iodine deficiency is the leading cause of preventable intellectual disability. Severe decreases can cause maternal thyroxine deficiency and can lead to maternal and fetal goiter, cretinism, and neonatal hypothyroidism. However, even mild deficiency may affect the cognitive abilities of affected children. Obstetric and perinatal consequences include increased pregnancy loss and infant mortality.⁴⁵

Vitamin A

There is risk to ingestion of supratherapeutic levels of certain micronutrients in pregnancy. For example, intake of greater than 10 000 IU daily of vitamin A in pregnancy is associated with an increased risk of fetal malformations.⁴⁶ Patients should be counseled that vitamins above the recommended doses are not necessarily beneficial and may be harmful.

Docosahexanoic Acid

There had been a surge in interest in docosahexanoic acid (DHA) supplements after several epidemiologic suggested benefits in infant neurocognitive scores as well as improved maternal depressive symptoms and maternal lipid profile. However, randomized controlled trials have been disappointing and suggest that DHA supplementation does not affect the incidence of preeclampsia, gestational diabetes, postpartum depression, or cognitive development of offspring.^39,40

Smoking

Tobacco use in pregnancy is associated with numerous harmful effects and is one of the most important modifiable risk factors in pregnancy. ACOG⁴⁷ reports that smoking is associated with intrauterine growth restriction, placenta previa, abruptio placentae, decreased maternal thyroid function, preterm premature rupture of membranes, low birth weight, perinatal mortality, and ectopic pregnancy.

An estimated 5–8% of preterm deliveries, 13–19% of term deliveries of infants with low birth weight, 23–34% cases of sudden infant death syndrome (SIDS), and 5–7% of preterm-related infant deaths can be attributed to prenatal maternal smoking.^47(p1241)

Obstetricians and midwives are present at an important time in a smoker’s life, when motivation to quit may be high and chances of success may be greater for their patient. It is critical that obstetricians screen all women presenting for prenatal care for tobacco use and take advantage of the opportunity to counsel and offer support in smoking cessation.⁴⁷

Alcohol

It is clear that alcohol affects pregnancies in a dose related manner. A recent meta-analysis noted that large amounts of alcohol in pregnancy are correlated with low birth weight, preterm birth, and small-for-gestational-age infants; however, light to moderate drinking did not show an effect.⁴⁸ A recent literature review on alcohol in pregnancy noted no increase in abnormal pregnancy outcomes with low-level alcohol consumption.⁴⁹ The authors advocated counseling against daily drinking but also noted that the dangers “of minimal alcohol use should not be overstated.” However, other studies have demonstrated that even small exposures to alcohol in early pregnancy have been associated with miscarriage.⁵⁰ Additionally, a study published in Pediatrics noted that very low levels of exposure to alcohol in utero (less than 1 drink per week) were associated with later behavior problems in girls.⁵¹ Another study noted a dose–response effect between in utero alcohol exposure and behavior problems at age 6 to 7 years.⁵² Pregnant women are advised to abstain from alcohol because the dose required to cause ill effects is unknown and may vary across individuals. Additionally, potential ill effects may not be apparent until years later.

Caffeine

Many expectant mothers worry about the effect of caffeine on fetal health. ACOG reports that moderate caffeine intake (less than 200 mg per day or about 12 oz of home-brewed coffee) is not associated with ill effects. There is evidence to suggest that preterm labor, fetal APGAR scores, miscarriage and even infant sleep patterns are not affected by moderate maternal caffeine use. ACOG endorses the view that moderate caffeine intake in pregnancy is safe, but also cautions that the effects of consumption of large amounts of caffeine on miscarriage and the effect of caffeine on intrauterine growth restriction are less clear.^53
-55

Herbal Medications

An analysis of data from the National Birth Defects Prevention Study found that the prevalence of use of herbal products 3 months before or during pregnancy was 10.9%. The authors conclude that up to 395 000 births in the United States had antenatal exposure to herbal products.⁵⁶ Because they are unregulated, the safety profile of these products is unknown.^57,58 Practitioners should initiate a frank discussion with all prenatal patients about the use of such products, emphasizing the lack of data to support safe use in pregnancy.

Exercise

ACOG encourages moderate exercise for 30 minutes a day for most, if not all, days of the week for healthy pregnant women without obstetric or medical complications. Generally, a large number of activities are safe, but avoidance of activities that carry a risk of abdominal trauma and falls, such a horseback riding, downhill skiing, and contact sports are discouraged. Scuba diving is also prohibited given the risk of decompression sickness.⁵⁹ Exercising during pregnancy has been shown to reduce excess weight gain and decrease weight retention postpartum.^59,60 Studies examining the impact of exercise before and during pregnancy on the development of gestational diabetes suggest a benefit, though there are no randomized controlled trials.^61,62

Special Situations

There are several notable clinical situations in nutrition and pregnancy that deserve extra attention as they grow increasingly common in the United States.

Multiples

The incidence of multiple pregnancies is increasing and presents additional nutritional challenges. Women pregnant with twins who start pregnancy with a normal BMI are advised by the Institute of Medicine to gain between 37 and 54 lbs by the end of pregnancy to optimize birth weight and minimize the morbidity associated with preterm birth and low birth weight. A recent review suggested a caloric intake for normal-BMI women with twins of 40 to 45 kcal/kg each day.⁶³ Iron, folate, calcium, magnesium, and zinc supplementation, and possible vitamin D and DHA dosed above that of a standard prenatal vitamin are recommended.⁶³ Many health care providers recommend additional input from a nutritionist to provide appropriate education and support for fetal growth for women with twins or higher order multiples.

Vegetarian Diets

The American Dietetic Association states that vegetarian diets are appropriate for all stages of life, including pregnancy and lactation, if carefully planned to meet increased demand for quality and quantity of macro- and micronutrients. Special attention should be given to the adequate intake of protein, n-3 fatty acids, iron, zinc, iodine, calcium, and vitamins D and B₁₂. Especially for vegan diets, eating foods fortified with vitamin B₁₂ such as yeast extracts, vegetable stock, veggie burgers, textured vegetable protein, soymilk, vegetable and sunflower margarines, and breakfast cereals is essential as vitamin B₁₂ is important for brain and neurocognitive development in the fetus and neonate.⁶⁴ Advice from a nutritionist can provide guidance.⁶⁵

Pregorexia

The media has reported on a new cultural trend of “pregorexia,” which refers to extreme dieting and exercise during pregnancy in order to control weight gain. Some women may feel increased pressure to gain minimal weight during pregnancy, and to lose it as quickly as possible postpartum, and the celebrity baby culture is a powerful force in changed expectations around what is normal in the peripartum period.^66
-69 More value is placed on maintaining a “thin” and stylish appearance during pregnancy than has been the case in previous decades. Efforts to achieve this may come at a detriment to the nutritional needs of the mother and fetus. Clinicians should be cognizant of this trend in popular culture and watchful regarding its effect on their patients. Health care providers are in a position to counteract this pressure and give reasonable and healthful advice on nutrition and weight gain in pregnancy.

Weight Loss Surgery

With one third of adult women in the United States now obese,^1,4 the numbers of women pursuing pregnancy after weight loss surgery continue to increase. ACOG reports that in 2004, half of bariatric procedures were performed in reproductive-age women.⁷⁰ Women undergoing bariatric surgery should be advised to avoid pregnancy for 12 to 18 months postoperatively, the time during which rapid weight loss occurs. They should be counseled that they are at increased risk of unplanned pregnancy during this time, as menstrual cycles may regulate and fertility increases with an improved metabolic profile.⁷⁰ In many studies, maternal and fetal outcomes improve after bariatric surgery, including an apparent decrease in the rate of gestational diabetes and hypertensive disorders, including preeclampsia.^70,71 Nevertheless, because these procedures result in malabsorption or restriction of intake of important micro- and macronutrients, special consideration to nutrition must be given to these patients in pregnancy. These women should be supplemented with a prenatal vitamin and multivitamin, taking care not to ingest vitamin A in excess of 5000 IU per day. If oral supplementation is not effective, parenteral must be considered. Protein, iron, vitamin B₁₂, folate, vitamin D, calcium,^70,71 vitamin A, and vitamin K deficiencies have been reported in this group.⁷⁰ Some experts recommend including a minimum of 60 g protein per day, 400 µg per day folate, 50 to 100 mg elemental iron, and at least 1000 mg calcium.⁷² Consideration may be given to evaluating for deficiencies at the beginning of pregnancy and targeting specific supplements. Alternatively, some practitioners evaluate hematocrit, iron, ferritin, calcium, and vitamin D trimesterly.

Adolescents

Pregnant adolescents are another group that requires special nutritional consideration. A recent study from the United Kingdom found that pregnant teens take in less than recommended vitamin B₁₂ and folate, which is associated with small-for-gestational-age births.⁷³ Adolescents who experience domestic violence, contract a sexually transmitted infection, or have an unplanned pregnancy are at higher risk for not achieving weight gain goals.⁷⁴ These risks factors may be especially prevalent in the teen population.

Pregnancy is a time of dynamic physiological change and development. Research is only starting to elucidate the way perinatal nutrition shapes the future health profile of the fetus and mother. Health practitioners have the opportunity to have a resonating impact on health outcomes by counseling this population.

References

Rasmussen

Yaktine

, eds. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: National Academies Press; 2009.

Institute of Medicine. Accelerating progress in obesity prevention: solving the weight of the nation. http://www.iom.edu/Reports/2012/Accelerating-Progress-in-Obesity-Prevention.aspx. Accessed June 9, 2012.

Glickman

Parker

Sim

De Valle Cook

Miller

, eds; Committee on Accelerating Progress in Obesity Prevention, Food and Nutrition Board. Accelerating Progress in Obesity Prevention: Solving the Weight of the Nation. Washington, DC: National Academies Press. http://books.nap.edu/openbook.php?record_id=13275. Accessed June 1, 2012.

American College of Obstetricians and Gynecologists. ACOG Committee Opinion number 315, September 2005. Obesity in pregnancy. Obstet Gynecol. 2005;106:671-675.

Power

Cogswell

Schulkin

. US obstetrician-gynecologist’s prevention and management of obesity in pregnancy. J Obstet Gynaecol. 2009;29:373-377.

Nascimento

Surita

Parpinelli

MÂ

Siani

Pinto

Silva

. The effect of an antenatal physical exercise programme on maternal/perinatal outcomes and quality of life in overweight and obese pregnant women: a randomised clinical trial. BJOG. 2011;118:1455-1463.

Quinlivan

Julania

Lam

. Antenatal dietary interventions in obese pregnant women to restrict gestational weight gain to institute of medicine recommendations: a meta-analysis. Obstet Gynecol. 2011;118:1395-1401.

Oteng-Ntim

Varma

Croker

Poston

Doyle

. Lifestyle interventions for overweight and obese pregnant women to improve pregnancy outcome: systematic review and meta-analysis. BMC Med. 2012;10:47.

Scholl

Hediger

Schall

Ances

Smith

. Gestational weight gain, pregnancy outcome, and postpartum weight retention. Obstet Gynecol. 1995;86:423-427.

10.

Louie

Brand-Miller

Markovic

Ross

Moses

. Glycemic index and pregnancy: a systematic literature review. J Nutr Metab. 2010;2010:282464.

11.

Tieu

Crowther

Middleton

. Dietary advice in pregnancy for preventing gestational diabetes mellitus. Cochrane Database Syst Rev. 2008;(2):CD006674.

12.

Nehring

Schmoll

Beyerlein

Hauner

von Kries

. Gestational weight gain and long-term postpartum weight retention: a meta-analysis. Am J Clin Nutr. 2011;94:1225-1231.

13.

Ohlin

Rössner

. Factors related to body weight changes during and after pregnancy: the Stockholm Pregnancy and Weight Development Study. Obes Res. 1996;4:271-276.

14.

Scholl

Chen

. Insulin and the ‘thrifty’ woman: the influence of insulin during pregnancy on gestational weight gain and postpartum weight retention. Matern Child Health J. 2002;6:255-261.

15.

Gould Rothberg

Magriples

Kershaw

Rising

Ickovics

. Gestational weight gain and subsequent postpartum weight loss among young, low-income, ethnic minority women. Am J Obstet Gynecol. 2011;204:52.e1-52.e11.

16.

Onyango

Nommsen-Rivers

Siyam

. Post-partum weight change patterns in the WHO Multicentre Growth Reference Study. Matern Child Nutr. 2011;7:228-240.

17.

Seki

Williams

Vuguin

Charron

. Mini review: epigenetic programming of diabetes and obesity: animal models. Endocrinology. 2012;153:1031-1038.

18.

Gillman

Barker

Bier

. Meeting report on the 3rd International Congress on Developmental Origins of Health and Disease (DOHaD). Pediatr Res. 2007:61(5 pt 1):625-629.

19.

Wadhwa

Buss

Entringer

Swanson

. Developmental origins of health and disease: brief history of the approach and current focus on epigenetic mechanisms. Semin Reprod Med. 2009;27:358-368.

20.

Ravelli

van der Meulen

Michels

. Glucose tolerance in adults after prenatal exposure to famine. Lancet. 1998;351:173-177.

21.

Agency for Toxic Substances & Disease Registry. Toxicological profile for mercury. http://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=115&tid=24. Accessed June 9, 2012.

22.

US Environmental Protection Agency. Fish consumption advisories—general information. http://water.epa.gov/scitech/swguidance/fishshellfish/fishadvisories/general.cfm. Accessed June 9, 2012.

23.

Davidson

Cory-Slechta

Thurston

. Fish consumption and prenatal methylmercury exposure: cognitive and behavioral outcomes in the main cohort at 17 years from the Seychelles Child Development Study. Neurotoxicology. 2011;32:711-717.

24.

Centers for Disease Control and Prevention. Toxoplasmosis. http://www.cdc.gov/parasites/toxoplasmosis/. Accessed June 9, 2012.

25.

Centers for Disease Control and Prevention. Listeria (listeriosis). http://www.cdc.gov/listeria/. Accessed June 9, 2012.

26.

Centers for Disease Control and Prevention. Salmonella. http://www.cdc.gov/salmonella/. Accessed May 9, 2013.

27.

Centers for Disease Control and Prevention. Salmonella is a sneaky germ: seven tips for safer eating. http://www.cdc.gov/Features/VitalSigns/FoodSafety/. Accessed May 9, 2013.

28.

Centers for Disease Control and Prevention. Salmonella—prevention. http://www.cdc.gov/salmonella/general/prevention.html. Accessed May 9, 2013.

29.

Scialli

Rarick

. Salmonella sepsis and second-trimester pregnancy loss. Obstet Gynecol. 1992;79(5 pt 2):820-821.

30.

Vandenberg

Maffini

Sonnenschein

Rubin

Soto

. Bisphenol-A and the great divide: a review of controversies in the field of endocrine disruption. Endocr Rev. 2009;30:75-95.

31.

Calafat

Wong

L-Y

Reidy

Needham

. Exposure of the U.S. population to bisphenol A and 4-tertiary-octylphenol: 2003-2004. Environ Health Perspect. 2008;116:39-44.

32.

Trasande

Attina

Blustein

. Association between urinary bisphenol A concentration and obesity prevalence in children and adolescents. JAMA. 2012;308:1113-1121.

33.

Lang

Galloway

Scarlett

. Association of urinary bisphenol A concentration with medical disorders and laboratory abnormalities in adults. JAMA. 2008;300:1303-1310.

34.

Braun

Kalkbrenner

Calafat

. Impact of early-life bisphenol A exposure on behavior and executive function in children. Pediatrics. 2011;128:873-882.

35.

Braun

Hauser

. Bisphenol A and children’s health. Curr Opin Pediatr. 2011;23:233-239.

36.

Groff

. Bisphenol A: invisible pollution. Curr Opin Pediatr. 2010;22:524-529.

37.

Welshons

Nagel

vom Saal

. Large effects from small exposures. III. Endocrine mechanisms mediating effects of bisphenol A at levels of human exposure. Endocrinology. 2006;147(6 suppl):S56-S69.

38.

US Preventive Services Task Force. Folic acid for the prevention of neural tube defects: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2009;150:626-631.

39.

Recommendations to prevent and control iron deficiency in the United States. Centers for Disease Control and Prevention. MMWR Recomm Rep. 1998;47(RR-3):1-29.

40.

ACOG Committee on Obstetric Practice. ACOG Committee Opinion No. 495: vitamin D: screening and supplementation during pregnancy. Obstet Gynecol. 2011;118:197-198.

41.

Chakhtoura

Azar

. The role of vitamin d deficiency in the incidence, progression, and complications of type 1 diabetes mellitus. Int J Endocrinol. 2013;2013:148673.

42.

Thomson

Spedding

Buckley

. Vitamin D in the aetiology and management of polycystic ovary syndrome. Clin Endocrinol (Oxf). 2012;77:343-350.

43.

Vanlint

. Vitamin D and obesity. Nutrients. 2013;5:949-956.

44.

Soheilykhah

Mojibian

Moghadam

Shojaoddiny-Ardekani

. The effect of different doses of vitamin D supplementation on insulin resistance during pregnancy. Gynecol Endocrinol. 2013;29:396-399.

45.

Stagnaro-Green

Sullivan

Pearce

. Iodine supplementation during pregnancy and lactation. JAMA. 2012;308:2463-2464.

46.

Rothman

Moore

Singer

Nguyen

Mannino

Milunsky

.Teratogenicity of high vitamin A intake. N Engl J Med. 1995;333:1369-1373.

47.

Committee opinion no. 471: smoking cessation during pregnancy. Obstet Gynecol. 2010;116:1241-1244.

48.

Patra

Bakker

Irving

Jaddoe

Malini

Rehm

. Dose-response relationship between alcohol consumption before and during pregnancy and the risks of low birthweight, preterm birth and small for gestational age (SGA)—a systematic review and meta-analyses. BJOG. 2011;118:1411-1421.

49.

Pregnancy and alcohol: occasional, light drinking may be safe. Prescrire Int. 2012;21:44-50.

50.

Andersen

Olsen

Grønbæk

Strandberg-Larsen

. Moderate alcohol intake during pregnancy and risk of fetal death. Int J Epidemiol. 2012;41:405-413.

51.

Sayal

Heron

Golding

Emond

. Prenatal alcohol exposure and gender differences in childhood mental health problems: a longitudinal population-based study. Pediatrics. 2007;119:e426-e434.

52.

Sood

Delaney-Black

Covington

. Prenatal alcohol exposure and childhood behavior at age 6 to 7 years: I. Dose-response effect. Pediatrics. 2001;108:E34.

53.

Jarosz

Wierzejska

Siuba

. Maternal caffeine intake and its effect on pregnancy outcomes. Eur J Obstet Gynecol Reprod Biol. 2012;160:156-160.

54.

Santos

Matijasevich

Domingues

. Maternal caffeine consumption and infant nighttime waking: prospective cohort study. Pediatrics. 2012;129:860-868.

55.

American College of Obstetricians and Gynecologists. ACOG Committee Opinion No. 462: moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010;116(2 pt 1)467-468.

56.

Louik

Gardiner

Kelley

Mitchell

. Use of herbal treatments in pregnancy. Am J Obstet Gynecol. 2010;202:439.e1-439.e10.

57.

Licata

Macaluso

Craxì

. Herbal hepatotoxicity: a hidden epidemic. Intern Emerg Med. 2013;8:13-22.

58.

Moussally

Oraichi

Bérard

. Herbal products use during pregnancy: prevalence and predictors. Pharmacoepidemiol Drug Saf. 2009;18:454-461.

59.

Committee on Obstetric Practice. ACOG Committee Opinion. Exercise during pregnancy and the postpartum period. Number 267, January 2002. American College of Obstetricians and Gynecologists. Int J Gynaecol Obstet. 2002;77:79-81.

60.

Stuebe

Oken

Gillman

. Associations of diet and physical activity during pregnancy with risk for excessive gestational weight gain. Am J Obstet Gynecol. 2009;201:58.e1-58.e8.

61.

Dempsey

Butler

Sorensen

. A case-control study of maternal recreational physical activity and risk of gestational diabetes mellitus. Diabetes Res Clin Pract. 2004;66:203-215.

62.

Dempsey

Sorensen

Williams

. Prospective study of gestational diabetes mellitus risk in relation to maternal recreational physical activity before and during pregnancy. Am J Epidemiol. 2004;159:663-670.

63.

Goodnight

Newman

. Optimal nutrition for improved twin pregnancy outcome. Obstet Gynecol. 2009;114:1121-1134.

64.

Black

. Effects of vitamin B12 and folate deficiency on brain development in children. Food Nutr Bull. 2008;29(2 suppl):S126-S131.

65.

Craig

Mangels

. Position of the American Dietetic Association: vegetarian diets. J Am Diet Assoc. 2009;109:1266-1282.

66.

Min

. In celebrity climate, from bump to paunch, pudgy moms can’t get a break. The New York Times. August 17, 2012. http://www.nytimes.com/2012/08/19/fashion/in-celebrity-climate-from-bump-to-paunch-pudgy-moms-cant-get-a-break.html?pagewanted=all&_r=0. Accessed July 10, 2013.

67.

Fiore

. Pregorexic: are some pregnant women putting their fetuses at risk? Fox News. December 7, 2011.

68.

Mayo Clinic. Pregorexia: a legitimate problem during pregnancy? http://www.mayoclinic.com/health/pregorexia/AN02077. Accessed May 28, 2012.

69.

During pregnancy, starving for two. Well. http://well.blogs.nytimes.com/2009/06/02/starving-for-twoa/. Accessed July 15, 2012.

70.

American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 105: bariatric surgery and pregnancy. Obstet Gynecol. 2009;113:1405-1413. http://www.acog.org/Resources_And_Publications/Practice_Bulletins/Committee_on_Practice_Bulletins_—_Obstetrics/Bariatric_Surgery_and_Pregnancy. Accessed July 31, 2012.

71.

Magdaleno

Jr Pereira

Chaim

Turato

. Pregnancy after bariatric surgery: a current view of maternal, obstetrical and perinatal challenges. Arch Gynecol Obstet. 2012;285:559-566.

72.

Beard

Bell

Duffy

. Reproductive considerations and pregnancy after bariatric surgery: current evidence and recommendations. Obes Surg. 2008;18:1023-1027.

73.

Baker

Wheeler

Sanders

. A prospective study of micronutrient status in adolescent pregnancy. Am J Clin Nutr. 2009;89:1114-1124.

74.

Berenson

Wiemann

Rowe

Rickert

. Inadequate weight gain among pregnant adolescents: risk factors and relationship to infant birth weight. Am J Obstet Gynecol. 1997;176:1220-1224.

Nutrition for a Healthy Pregnancy