The accurate prediction of thermal sensation for pregnant women is not achievable with existing predicted mean vote (PMV) models, likely due to alterations in metabolic rate associated with gestation. Existing studies and standards lack data on the metabolic rates of pregnant women in China across trimesters, making it impossible to verify whether deviations in the PMV model are associated with changes in metabolic rate. This study recruited 30 women with pre-pregnancy normal body mass index (BMI) at different gestational stages. Indirect calorimetry measured sitting-still metabolic rate and respiratory parameters, and the PMV model was modified based on actual metabolic rates. Results indicate that the sitting-still metabolic rates of 0.86, 1.06 and 1.21 met were measured for pregnant women, corresponding to the three pregnancy stages in order. Metabolic rates differed significantly between the first and third trimesters of pregnancy (p < 0.01). The modified model (termed PMVm), which incorporated measured metabolic rates, showed a 22% improvement in accuracy during the third trimester, with no significant effect in the first or second trimesters. These findings contribute to the refinement of thermal comfort theory for pregnant women, offering data references to improve the precision of thermal model predictions.
LiHHuHYWuZYKongXFFanM. Modified predicted mean vote models for human thermal comfort: an ASHRAE database-based evaluation. Renew Sustain Energy Rev2025; 209: 115042.
2.
SekharSC. Thermal comfort in air-conditioned buildings in hot and humid climates–why are we not getting it right?Indoor Air2016; 26(1): 138–152.
3.
ZhangFDe DearRHancockP. Effects of moderate thermal environments on cognitive performance: a multidisciplinary review. Appl Energy2019; 236: 760–777.
4.
ZhangSChengYOladokunMOWuYXLinZ. Improving predicted mean vote with inversely determined metabolic rate. Sustain Cities Soc2020; 53: 101870.
5.
FangerPO. Calculation of thermal comfort: introduction of a basic comfort equation. Ashrae Trans1967; 73: 1–20.
6.
PereiraPFDCBrodayEEXavierAAP. Thermal comfort applied in hospital environments: a literature review. Appl Sci2020; 10(20): 1–22.
7.
PengTZhangYCJiangXYYangYPFangZSZhengZM. Investigation of pregnant women thermal comfort in the waiting area of the hospital in South China, Guangzhou. J Build Eng2021; 44: 103254.
8.
YangSJWangLJZhangHYangJLiWHZhangYJ. Field study on pregnant women's thermal preference in different trimesters in winter. J Therm Biol2023; 118: 103744.
9.
WuWLFangZSJiXFZhengZM. Predicted mean vote model for thermal comfort evaluation of pregnant women considering the effects of metabolic rate. Indoor Built Environ2023; 32: 667–680.
10.
TaranikantiM. Physiological changes in cardiovascular system during normal pregnancy: a review. Indian J Cardiovasc Dis Women Wincars2018; 3: 62–67.
11.
WeinbergerSEWeissSTCohenWRWeissJWJohnsonTS. Pregnancy and the lung. Am Rev Respir Dis1980; 121(3): 559–581.
12.
ClappJF. The changing thermal response to endurance exercise during pregnancy. Am J Obstet Gynecol1991; 165(6): 1684.
13.
WangLJZhangMMZuoGDZhengSJiangJ. Differences in thermal comfort between male and female with the same thermal preference in summer. J Xi'an Polytechnic Univ2022; 36(1): 70–75. in Chinese.
14.
YangLZhaoSKGaoSZhangHArensEZhaiYC. Gender differences in metabolic rates and thermal comfort in sedentary young males and females at various temperatures. Energy Build2021; 251: 111360.
15.
ZhangJHLuJDengWBeccarelliPLunIYF. Investigation of thermal comfort and preferred temperatures among rural elderly in Weihai, China: considering metabolic rate effects. J Build Eng2024; 97: 110940.
16.
LuoMWangZKeKCaoBZhaiYCZhouX. Human metabolic rate and thermal comfort in buildings: the problem and challenge. Build Environ2018; 131: 44–52.
17.
ISO 7730:2005. Ergonomics of the thermal environment Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. International Organization for Standardization, Geneva, 2005.
18.
ANSI/ASHRAE Standard 55-2023. Thermal Environment Conditions for Human Occupancy. Atlanta: ASHRAE, 2023.
19.
BhardwajSVermaDKapoorS. Body composition and basal metabolic rate in pregnant women. Anthropol Rev2013; 76(2): 163–171.
20.
DinuMNapoletanoAGiangrandiILottiSRuotoloARendaINardoneLPaternòISeravalliVAsensi1MTPagliaiGColombiniBTommasoMDSofiF. Exploring basal metabolic rate and dietary adequacy in twin pregnancies: the VENERE study. Nutr Metab2024; 21: 99.
21.
YanovskiSZReynoldsJCBoyleAJYanovskiJA. Resting metabolic rate in African-American and Caucasian girls. Obes Res1997; 5(4): 321–325.
22.
LofMOlaussonHBostromKJanerot-SjöbergBSohlstromAForsumE. Changes in basal metabolic rate during pregnancy in relation to changes in body weight and composition, cardiac output, insulin-like growth factor I, and thyroid hormones and in relation to fetal growth. Am J Clin Nutr2005; 81(3): 678–685.
23.
PengTFangWXJiangXYYangYPFangZSZhengZM. Comparison of the thermal comfort of pregnant women at different stages of pregnancy in a subtropical region. Build Environ2022; 219: 109121.
24.
FabbriKGaspariJVandiL. Indoor thermal comfort of pregnant women in hospital: a case study evidence. Sustainability2019; 11: 6664.
25.
XuYWangLJLiuHTZhaiMMZhangMJYinHGChenMZ. Experimental studies on the correlations of male respiratory parameters with their body composition. Energy Build2025; 338: 115666.
26.
MelzerKSchutzYSoehnchenNOthenin GirardVMartinez de TejadaBPichardCLrionOBoulvainMKasyerB. Prepregnancy body mass index and resting metabolic rate during pregnancy. Ann Nutr Metab2010; 57: 221–227.
27.
ZhaoSKYangLGaoSYanHYZhangHArensELiuSZhaiYC. Influencing factors of metabolic rates and their implications in thermal comfort research. Energy Build2025; 339: 115777.
28.
KazkazMPavelekM. Operative temperature and globe temperature. Eng Mech2013; 20: 319–325.
29.
HillsAPMokhtarNByrneNM. Assessment of physical activity and energy expenditure: an of objective measures. Front Nutr2014; 1: 5.
30.
JinRLiuXZZhangHYeTZZhengWD. Metabolic rate measuring with indirect calorimetry for thermal comfort evaluation. Appl Sci2024; 14: 5363.
31.
ISO 8996-2021. Ergonomics of the Thermal Environment - Determination of Metabolic Rate. International Organization for Standardization. Geneva. 2021.
32.
LanLLianZW. Application of statistical power analysis - how to determine the right sample size in human health, comfort and productivity research. Build Environ2010; 45: 1202–1213.
33.
ZhangSChengYFangZSLinZ. Improved algorithm for adaptive coefficient of adaptive Predicted Mean Vote (aPMV). Build Environ2019; 163: 106318.
34.
WangLJLiuHTLiYYangSJZhangHYangJ. Analysis of clothing thermal resistance and thermal comfort of pregnant women in maternity care space in autumn. Basic Sci J Text Univ2024; 37(5): 83–89.
35.
MaSYDengWLuJZhouTYLiuBJ. Investigation of thermal comfort and preferred temperatures for healthcare staff in hospitals in Ningbo, China. J Build Eng2023; 80: 108029.
36.
YaoRLiBZLiuJ. A theoretical adaptive model of thermal comfort–adaptive predicted mean vote (aPMV). Build Environ2009; 44(10): 2089–2096.
37.
KimJTLimJHChoSHYunGY. Development of the adaptive PMV model for improving prediction performances. Energy Build2015; 98: 100–105.
38.
LuYFWangYTianTBaZG. Investigation of thermal comfort for patients and visitors in a hospital in Lanzhou, Northwest China. Build Serv Eng Res Technol2025; 46: 793–814.
39.
ZhangSXYaoRMLiBZ. An improved approach for solving the adaptive coefficient in the aPMV (adaptive predictive mean vote) index. Build Environ2024; 256: 111481.
40.
ButteNFKingJC. Energy requirements during pregnancy and lactation. Public Health Nutr2005; 8: 1010–1027.
41.
PiersLDiggaviSThangamSVan RaaijJShettyPHautvastJ. Changes in energy expenditure, anthropometry, and energy intake during the course of pregnancy and lactation in well-nourished Indian women. Am J Clin Nutr1995; 61: 501–513.
42.
ChiharaHOtsuboYYoneyamaYSawaRSuzukiSPowerGArakiT. Basal metabolic rate in hyperemesis gravidarum: comparison to normal pregnancy and response to treatment. Am J Obstet Gynecol2003; 188: 434–438.
43.
PitkinRM. Nutritional support in obstetrics and gynecology. Clin Obstet Gynecol1976; 19: 489–513.
44.
MeoSAHassainA. Metabolic physiology in pregnancy. J Pak Med Assoc2016; 66: S8–S10.
45.
HegewaldMJCrapoRO. Respiratory physiology in pregnancy. Clin Chest Med2011; 32: 1–13.
46.
AjjimapornASomprasitCChaunchaiyakulR. A cross-sectional study of resting cardio-respiratory and metabolic changes in pregnant women. J Phys Ther Sci2014; 26: 779–782.
47.
TeliADoddamaniPBagaliS. A study of respiratory rate, tidal volume, inspiratory capacity and inspiratory reserve volume in different trimesters of pregnancy. Int J Health Allied Sci2013; 2: 294–297.
48.
ShailajaDYSrikanthDS. Lung function tests in different trimesters of pregnancy. Indian J Basic Appl Med Res2013; 3: 285–292.
49.
Soma-PillayPNelson-PiercyCTolppanenHMebazaaA. Physiological changes in pregnancy. Cardiovasc J Afr2016; 27: 89–94.
50.
ForsumEJanerot-SjöbergBLöfM. MET-values of standardised activities in relation to body fat: studies in pregnant and non-pregnant women. Nutr Metab2018; 15: 45.
51.
ZhaiYCLiMHGaoSYangLZhangHArensEGaoY. Indirect calorimetry on the metabolic rate of sitting, standing and walking office activities. Build Environ2018; 145: 77–84.
52.
HartRMcMahonCA. Mood state and psychological adjustment to pregnancy. Arch Women’s Ment Health2006; 9: 329–337.
53.
CharkoudianNStachenfeldN. Sex hormone effects on autonomic mechanisms of thermoregulation in humans. Auton Neurosci2016; 196: 75–80.
54.
LiuJYaoRMcCloyR. A method to weight three categories of adaptive thermal comfort. Energy Build2012; 47: 312–320.
55.
BranchDW. Physiologic adaptations of pregnancy. Am J Reprod Immunol1992; 28: 120–122.
56.
JeeSBSawalA. Physiological changes in pregnant women due to hormonal changes. Cureus2024; 16(3): e55544.
57.
HoytTArensEZhangH. Extending air temperature setpoints: simulated energy savings and design considerations for new and retrofit buildings. Build Environ2015; 88: 89–96.
58.
PersilyA. Indoor carbon dioxide concentrations in ventilation and indoor air quality standards. In: Proc. 36th AIVC, Conf. Eff. Vent. High Perform. Build 2015, 23–24 September 2015, Madrid, Spain, pp. 810–819.
