Sage Journals: Discover world-class research

Abstract

BACKGROUND:

The aim of our study is to describe maternal and neonatal morbidity and mortality in patients undergoing trial of labor after cesarean from the Consortium on Safe Labor.

METHODS:

This was a secondary analysis of the Consortium on Safe Labor database, a retrospective cohort study over a 7 year study period. Maternal and neonatal outcomes were evaluated based on desired delivery mode: planned elective repeat cesarean delivery or trial of labor after cesarean.

RESULTS:

Of 9858 patients in our analysis, our study population had 4400 patients (45%) who desired trial of labor after cesarean and 5458 patients (55%) who desired elective repeat cesarean delivery. Women who attempted trial of labor after cesarean compared to those who had an elective repeat cesarean delivery were more likely to have an obstetric hemorrhage (adjusted odds ratio 1.6; 95% CI 1.3 –2.0) and blood transfusion (adjusted odds ratio 2.3; 95% CI 1.6 –3.2).

CONCLUSION:

Maternal morbidity in women undergoing trial of labor after cesarean was predominantly hemorrhage-related.

Keywords

Cesarean delivery maternal morbidity obstetric hemorrhage perinatal counseling trial of labor after cesarean

1 Introduction

The rate of cesarean delivery (CD) in the United States has steadily increased from 5% in the 1970 s to over 30% in modern cohorts [1 –5]. This increase can be attributed to both increasing primary CD rates and a declining number of women undergoing trial of labor after cesarean (TOLAC) [6, 7].

Repeat CDs confer an increased surgical risk of infection, injury, venous thromboembolism, and the need for an emergency hysterectomy when compared women who have a successful vaginal delivery [8]. In response to rising rates of CD and morbidity associated with higher order CD, national organizations have emphasized the importance of counseling women for TOLAC and facilitating access to facilities that are able to provide TOLAC [3, 7]. TOLAC has a demonstrated favorable safety profile in historical cohorts but is not without potential risk. Women undergoing TOLAC have both a greater risk for maternal morbidity and neonatal morbidity than elective repeat CD, although the absolute risk of complications remain low [9, 10].

The landscape surrounding TOLAC has changed considerably. We have seen significant evolution of practice patterns, increasing acceptance surrounding TOLAC, and changes in maternal demographic characteristics. TOLAC guidelines have been expanded to include women with two prior cesarean deliveries and permit an induction of labor [3, 11]. Counseling women with a prior CD regarding desired mode of delivery in future pregnancies has become a frequent component of routine prenatal care. We sought to expand the existing literature on maternal and neonatal risk associated with TOLAC to seek targeted counseling using the Consortium on Safe Labor.

2 Methods

We conducted a retrospective secondary analysis of women undergoing TOLAC in the Consortium on Safe Labor, a multi-site observational cohort study of women delivering at or beyond 23 weeks of gestation over a seven year study period. This database was generated from 19 hospitals in the United States and includes patient demographic information, medical history, labor course, and delivery outcomes. The primary outcome for this study was rate of uterine rupture by desired delivery mode (planned elective CD versus TOLAC). Secondary outcomes included uterine dehiscence, blood transfusion, hemorrhage, hysterectomy, endometritis, maternal death, and neonatal outcomes including neonatal intensive care unit admission, respiratory distress syndrome, seizure, asphyxia, and death.

Women met inclusion criteria for our study if they had a history of any prior CD. Cases were categorized as either delivered by elective repeat CD or attempting TOLAC by spontaneous labor, augmentation, or induction of labor. This was achieved using the following coding of the Consortium on Safe Labor variables. For inclusion in the elective repeat CD cohort, a patient had to have a history of a prior CD and elective CD code. For inclusion in the TOLAC cohort, a patient had to have a history a prior CD, an admission dilation ≥4 centimeters or induction of labor with oxytocin, and the absence of an elective CD code.

Demographic data were compared across groups using Student’s t-test for continuous variables and Chi-square or Fischer’s exact test for categorical variables. A p-value of < 0.05 was considered significant. Multivariable logistic regression was used to describe the association between TOLAC and markers of maternal and neonatal morbidity and mortality. An adjusted analysis was performed including significant maternal variables identified using backward elimination of covariates with p > 0.3. Variables included in the final multivariable adjusted model included age, race, parity, insurance, BMI, gestational age at delivery, diabetes, anemia, thrombocytopenia, asthma, chronic hypertension, eclampsia, preeclampsia, gestational hypertension, underlying heart disease, seizure history, thyroid disease, HIV, tobacco, alcohol, or illicit drug use, placenta previa, placental abruption, fetal sex, history of preterm birth, urinary tract infection in pregnancy, sexually transmitted disease, and oxytocin use during labor. This study was approved by the Institutional Review Board and considered exempt (IRB #071734).

3 Results

Out of 228652 women in the Consortium on Safe Labor, 31329 (14%) women had a prior CD. Of these patients, 5458 (17%) were specifically coded for elective CD, and these defined our elective repeat CD group. 4400 (2%) women were undergoing TOLAC. Thus, there were 9858 delivery admissions with complete information for this analysis: 5458 (55%) women undergoing elective repeat CD and 4400 (45%) undergoing TOLAC. Of 4400 patients who desired vaginal delivery, 3162 (72%) achieved a vaginal birth and 1238 (28%) had a failed TOLAC and underwent repeat CD.

Women attempting TOLAC were on average younger, with a lower body mass index (BMI), more likely to be white, deliver preterm, have a smaller neonatal birth weight, and have had only one prior cesarean delivery (p < 0.01). Patients undergoing TOLAC were less likely to use tobacco, but this did not reach statistical significance (p = 0.08). Groups had similar amounts of underlying maternal comorbidity (p = 0.7) (Table 1).

Table 1
Maternal demographic data in women undergoing scheduled elective cesarean delivery and those attempting trial of labor after cesarean (TOLAC)

Maternal characteristics TOLAC Elective repeat p-value

(n = 4400) CD (n = 5458)

Maternal age at delivery (years)

≤17 12 (0.3%) 26 (0.5%) <0.01

18–34 3376 (76.9%) 3875 (71.2%)

≥35 1002 (22.8%) 1542 (28.3%)

Race or ethnicity

Black 1018 (23.1%) 1689 (31.0%) <0.01

White 2090 (47.5%) 2374 (43.5%)

Hispanic 800 (18.2%) 961 (17.6%)

Asian 206 (4.7%) 254 (4.7%)

Other 286 (6.5%) 180 (3.3%)

Marital status

Single 1345 (30.6%) 1674 (30.7%) 0.75

Married 2785 (63.3%) 3425 (62.8%)

Other 270 (6.1%) 359 (6.5%)

Tobacco use 322 (7.3%) 451 (8.3%) 0.08

BMI (kg/m³) 26.5±6.8 27.5±7.5 <0.01

Maternal comorbidity* 1028 (23.4%) 1291 (23.7%) 0.74

Gestational age at delivery (weeks)

< 37 627 (14.3%) 644 (11.8%) <0.01

37–41 3619 (82.3%) 4767 (87.3%)

> 41 154 (3.5%) 47 (0.9%)

Neonatal birth weight (grams)

≤1,500 99 (2.5%) 57 (1.2%) <0.01

1,501–2,499 313 (7.9%) 320 (6.5%)

> 2,500 3556 (89.6%) 4588 (92.4%)

Prior CD

1 3664 (93.3%) 4615 (87.5%) <0.01

2 231 (5.9%) 553 (10.5%)

≥3 32 (0.8%) 105 (2.0%)

Maternal characteristics	TOLAC	Elective repeat	p-value
Maternal age at delivery (years)
≤17	12 (0.3%)	26 (0.5%)	<0.01
18–34	3376 (76.9%)	3875 (71.2%)
≥35	1002 (22.8%)	1542 (28.3%)
Race or ethnicity
Black	1018 (23.1%)	1689 (31.0%)	<0.01
White	2090 (47.5%)	2374 (43.5%)
Hispanic	800 (18.2%)	961 (17.6%)
Asian	206 (4.7%)	254 (4.7%)
Other	286 (6.5%)	180 (3.3%)
Marital status
Single	1345 (30.6%)	1674 (30.7%)	0.75
Married	2785 (63.3%)	3425 (62.8%)
Other	270 (6.1%)	359 (6.5%)
Tobacco use	322 (7.3%)	451 (8.3%)	0.08
BMI (kg/m³)	26.5±6.8	27.5±7.5	<0.01
Maternal comorbidity*	1028 (23.4%)	1291 (23.7%)	0.74
Gestational age at delivery (weeks)
< 37	627 (14.3%)	644 (11.8%)	<0.01
37–41	3619 (82.3%)	4767 (87.3%)
> 41	154 (3.5%)	47 (0.9%)
Neonatal birth weight (grams)
≤1,500	99 (2.5%)	57 (1.2%)	<0.01
1,501–2,499	313 (7.9%)	320 (6.5%)
> 2,500	3556 (89.6%)	4588 (92.4%)
Prior CD
1	3664 (93.3%)	4615 (87.5%)	<0.01
2	231 (5.9%)	553 (10.5%)
≥3	32 (0.8%)	105 (2.0%)

Data are N (%) or mean±standard deviation. Abbreviations: TOLAC = trial of labor after cesarean; BMI = body mass index; CD = cesarean delivery. *Includes asthma, diabetes, chronic hypertension, seizure disorder, thyroid disease, renal disease, and connective tissue disease.

Rate of uterine rupture was significantly higher in patients undergoing TOLAC versus elective repeat CD, although the absolute rate was low in both groups (p < 0.001). Women undergoing TOLAC compared to those who had an elective repeat CD were more likely to have uterine rupture (OR 3.1; 95% CI 1.2–8.0). However, this was no longer significant after adjusting for potential confounders (aOR 2.0; 95% CI 0.8–5.5). Patients undergoing TOLAC had a higher incidence of hemorrhage and transfusion compared to those having an elective repeat CD (p < 0.001). The relationship between TOLAC and hemorrhage or transfusion remained significant when adjusting for confounders (aOR 1.6; 95% CI 1.3–2.0 and aOR 2.3; 95% CI 1.6–3.2, respectively). Women undergoing TOLAC were more likely to experience more than one adverse event (p < 0.001) but this finding was primarily driven by hemorrhage or transfusion (Table 2).

Table 2

Maternal and neonatal outcomes in women undergoing trial of labor after caesarean compared to elective repeat cesarean delivery

	TOLAC	Elective Repeat	p-value	Odds ratio	Adjusted odds
	(N = 4,400)	CD (N = 5,458)		(95% CI)	ratio* (95% CI)
Maternal Outcomes
Uterine Rupture	15 (0.3)	6 (0.1)	<0.001	3.1 (1.2 –8.0)	2.0 (0.8 –5.5)
Uterine Dehiscence	9 (0.2)	8 (0.2)	0.5	1.4 (0.6 –3.6)	1.0 (0.3 –3.2)
Transfusion	113 (2.6)	61 (1.1)	<0.001	2.3 (1.7 –3.2)	2.3 (1.6 –3.2)
Hemorrhage	327 (7.4)	189 (3.5)	<0.001	2.2 (1.9 –2.7)	1.6 (1.3 –2.0)
Hysterectomy	4 (0.1)	12 (0.2)	0.1	0.4 (0.1 –1.3)	0.1 (0.01 –0.3)
Endometritis	13 (0.3)	33 (0.6)	<0.001	0.5 (0.3 –0.9)	0.5 (0.2 –0.9)
Maternal Death	0	0	–	–	–
One or more of the above events	352 (8)	233 (4.3)	<0.001	2.0 (1.6 –2.3)	1.5 (1.2 –1.8)
Neonatal Outcomes
NICU Admission	569 (13)	617 (11)	0.01	1.2 (1.0 –1.3)	1.2 (1.0 –1.4)
Respiratory Distress Syndrome	155 (3.5)	183 (3.4)	0.7	1.1 (0.9 –1.3)	0.8 (0.6 –1.1)
Seizure	13 (0.3)	8 (0.2)	0.1	2.0 (0.8 –4.9)	2.1 (0.8 –5.3)
Asphyxia	12 (0.3)	4 (0.1)	0.01	3.7 (1.2 –12)	3.3 (1.0 –11)
Neonatal Death	16 (0.4)	16 (0.3)	0.6	1.3 (0.6 –2.5)	0.6 (0.2 –1.4)

Data are N (%). Abbreviations: TOLAC = trial of labor after cesarean; NICU = neonatal intensive care unit admission; CD = cesarean delivery. *adjusted for age, race, parity, insurance, BMI, gestational age at delivery, diabetes, anemia, thrombocytopenia, asthma, chronic hypertension, eclampsia, preeclampsia, gestational hypertension, underlying heart disease, seizure history, thyroid disease, HIV, tobacco, alcohol, or illicit drug use, placenta previa, placental abruption, fetal sex, history of preterm birth, urinary tract infection in pregnancy, sexually transmitted disease, and oxytocin use during labor.

Conversely, women undergoing TOLAC were significantly less likely to be diagnosed with endometritis (aOR 0.5; 95% CI 0.2–0.9). Rate of hysterectomy was lower in women undergoing TOLAC when compared to women who had elective CD, but overall rates were low and this did not reach significance (p = 0.1). There were no maternal deaths in our analysis cohort.

Neonatal intensive care unit admission was significantly higher in patients undergoing TOLAC compared to elective CD (aOR 1.2; 95% CI 1.0 –1.3). Rates of neonatal respiratory distress syndrome, seizure, and neonatal death did not vary significantly between groups. We saw higher rates of neonatal asphyxia in women attempting TOLAC; however absolute numbers were small and our estimates for this outcome are imprecise.

4 Discussion

Our findings remonstrate that there is an association between TOLAC and perinatal morbidity but highlights that severe maternal or neonatal complications are rare. Hemorrhage and transfusion were the most commonly observed maternal complication in our cohort of women undergoing TOLAC. This association remained significant even when adjusting for potential confounders that could impact hemorrhage risk. Our work emphasizes a persistent and strong association of TOLAC with hemorrhage and hemorrhage-associated morbidity.

It is well established that TOLAC is associated with uterine rupture, a severe intrapartum complication that can lead to significant maternal and neonatal morbidity [3 , 13]. Rates of uterine rupture in our study were low and marginally lower than what is reported in most large historical cohort [10 , 12–14]. In our study, after we adjust for confounders, there was no difference in the risk of uterine rupture between women undergoing TOLAC compared to elective repeat CD.

Further research is needed to identify patient characteristics and system practices surrounding TOLAC that could impact perinatal outcomes. Lehmann et al. described factors associated with successful TOLAC in low-risk pregnancies. They observed that there was a temporal effect to these determinants, suggesting that outcomes for women undergoing TOLAC are not static and rather fluctuate with changes in patient characteristics and practice patterns [15]. Multiple patient and provider-level characteristics can influence hemorrhage risk, uterine rupture rates, and other perinatal morbidity and may contribute to the differences seen across studies, patient populations, and time [16 –19]. Patient characteristics in women undergoing TOLAC continue to change and evolve and historical risk associated with TOLAC may not adequately describe modern patient populations. More studies in large, diverse, and modern patient populations across urban and rural healthcare settings are essential to better estimate perinatal risk in women undergoing TOLAC and to better describe the association of hemorrhage-related morbidity and TOLAC.

This study offers insight into maternal and neonatal risk associated with TOLAC from 2002–2008. The large sample size makes it possible to detect small differences in uterine rupture and hemorrhage risk significant and provides a reliable estimate. However, this study has several important limitations. Though our analysis is more contemporary than some large landmark TOLAC trials, it describes a cohort more than a decade old and may fail to capture modern risk [10, 20]. Due to constraints in performing a secondary analysis of an existing database, our study is at risk for misclassification bias. We implemented strict inclusion and exclusion criteria for our analysis which should minimize risk of misclassification. Additionally, because this is a secondary analysis of the Consortium on Safe Labor there are limitations to interpretations and elaborations on existing variables. Due to database limitations, we are unable to define important parameters surrounding obstetric hemorrhage and transfusion, including hemorrhage etiology, estimated blood loss, number of units transfused, or type of product transfused. This analysis did not account for patients with known placenta accreta spectrum disorder when evaluating rates of hysterectomy. We were unable to control for underlying fetal anomalies or known lethal fetal conditions when evaluating neonatal outcomes.

We demonstrate that maternal morbidity in women undergoing TOLAC is predominantly related to obstetric hemorrhage and transfusion. Mode of delivery counseling is a critical component of routine prenatal care for women with a prior CD. Our work emphasizes the need to shift the conversation surrounding TOLAC counseling and management to focus on hemorrhage-related morbidity and to implement strategies to reduce maternal hemorrhage-related risk associated with TOLAC.

Footnotes

Acknowledgment

We would like to acknowledge Ahmed Ebeid, a research coordinator at the department of obstetrics and gynecology in George Washington University Hospital, who helped in the submission process of this paper.

Disclosure of interest

The authors report no conflicts of interest. The authors report there are no competing interests to disclose.

Funding statement

The authors have no financial support to disclose for this study.

References

Kozhimannil

, Law

, Virnig

. Cesarean delivery rates vary tenfold among US hospitals; reducing variation may address quality and cost issues. Health Aff (Millwood). 2013;32(3):527–35.

Hamilton

, Martin

, Osterman

MJK

[cited 2021 Jun 5]. Births: Provisional data for 2020 [Internet]. Available from: https://www.cdc.gov/nchs/data/vsrr/vsrr012-508.pdf

ACOG Practice Bulletin No. 205. Vaginal Birth After Cesarean Delivery. Obstet Gynecol. 2019;133(2).

MacDorman

, Menacker

, Declercq

. Cesarean birth in the United States: epidemiology, trends, and outcomes. Clin Perinatol. 2008;35(2):293–307, v.

MacDorman

, Declercq

, Menacker

. Recent trends and patterns in cesarean and vaginal birth after cesarean (VBAC) deliveries in the United States. Clin Perinatol. 2011;38(2):179–92.

Uddin

, Simon

. Rates and success rates of trial of labor after cesarean delivery in the United States, 1990-2009. Matern Child Health J. 2013;17(7):1309–14.

National Institutes of Health Consensus Development conference statement:Vaginal birth after cesarean:Newinsights March 8-10, 2010. Obstet Gynecol. 2010;115(6):1279–1295.

Silver

, Landon

, Rouse

, Leveno

, Spong

, Thom

, et al. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Maternal morbidity associated with multiple repeat cesarean deliveries.. Obstet Gynecol. 2006;107(6):1226–32.

Kok

, Ruiter

, Lindeboom

, de Groot

, Pajkrt

, Mol

, et al. Elective repeat cesarean delivery compared with trial of labor after a prior cesarean delivery: A propensity score analysis. Eur J Obstet Gynecol Reprod Biol.2015;195 214–8.

10.

Landon

, Hauth

, Leveno

, Spong

, Leindecker

, Varner

, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med. 2004;351(25).

11.

Davidson

, Bellows

, Shah

, Hawley

, Drexler

, Gandhi

, et al. Outcomes associated with trial of labor after cesarean in women with one versus two prior cesarean deliveries after a change in clinical practice guidelines in an academic hospital. J Matern Neonatal Med. 2020;33(9).

12.

Guise

J-M

, Eden

, Emeis

, Denman

, Marshall

, Fu

, et al. Vaginal birth after cesarean: New insights. Evid Rep Technol Assess. 2010;191 1–397.

13.

Guise

J-M

, Denman

, Emeis

, Marshall

, Walker

, Fu

, et al. Vaginal birth after cesarean. Obstet Gynecol. 2010;115(6) 1267–78.

14.

Grobman

, Gilbert

, Landon

, Spong

, Leveno

, Rouse

, et al. Outcomes of induction of labor after one prior cesarean. Obstet Gynecol. 2007;109(2, Part 1) 262–9.

15.

Lehmann

, Baghestan

, Børdahl

, Irgens

, Rasmussen

. Lowrisk pregnancies after a cesarean section: Determinants of trial of labor and its failure. PLoS One. 2020;15(1):e0226894.

16.

Landon

. Predicting uterine rupture in women undergoing trial of labor after prior cesarean delivery. Semin Perinatol. 2010;34(4) 267–71.

17.

Hammoud

, Hendler

, Gauthier

, Berman

, Sansregret

, Bujold

. The effect of gestational age on trial of labor after Cesarean section. J Matern Fetal Neonatal Med. 2004;15(3) 202–6.

18.

Al-Zirqi

, Daltveit

, Forsén

, Stray-Pedersen

, Vangen

. Risk factors for complete uterine rupture. Am J Obstet Gynecol. 2017;216(2) 165.e1–165.e8.

19.

Wingert

, Johnson

, Featherstone

, Sebastianski

, Hartling

, Douglas Wilson

. Adjunct clinical interventions that influence vaginal birth after cesarean rates: systematic review. BMC Pregnancy Childbirth. 2018;18(1) 452.

20.

Landon

, Leindecker

, Spong

, Hauth

, Bloom

, Varner

, et al. The MFMU Cesarean Registry: Factors affecting the success of trial of labor after previous cesarean delivery. Am J Obstet Gynecol. 2005;193(3 Pt 2) 1016–23.

Trial of labor after cesarean: Maternal and neonatal outcomes from the Consortium on Safe Labor

Abstract

BACKGROUND:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1 Introduction

2 Methods

3 Results

Footnotes

Acknowledgment

Disclosure of interest

Funding statement

References