Associations of maternal ambient temperature exposures during pregnancy with the placental weight, volume and PFR: A birth cohort study in Guangzhou, China

Jiaqi Wang; Xin Liu; Moran Dong; Xiaoli Sun; Jianpeng Xiao; Weilin Zeng; Jianxiong Hu; Xing Li; Lingchuan Guo; Zuhua Rong; Guanhao He; Jiufeng Sun; Dan Ning; Dengzhou Chen; Yonghui Zhang; Bo Zhang; Wenjun Ma; Tao Liu

doi:10.1016/j.envint.2020.105682

Associations of maternal ambient temperature exposures during pregnancy with the placental weight, volume and PFR: A birth cohort study in Guangzhou, China

Environ Int. 2020 Jun:139:105682. doi: 10.1016/j.envint.2020.105682. Epub 2020 Apr 2.

Authors

Jiaqi Wang¹, Xin Liu¹, Moran Dong¹, Xiaoli Sun², Jianpeng Xiao¹, Weilin Zeng¹, Jianxiong Hu¹, Xing Li¹, Lingchuan Guo¹, Zuhua Rong¹, Guanhao He¹, Jiufeng Sun¹, Dan Ning¹, Dengzhou Chen¹, Yonghui Zhang³, Bo Zhang⁴, Wenjun Ma¹, Tao Liu⁵

Affiliations

¹ Guangdong Provincial Institute of Public Health, Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China.
² Gynecology Department, Guangdong Women and Children Hospital, Guangzhou 511442, China.
³ Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China.
⁴ Food Safety and Health Research Center, School of Public Health, Southern Medical University, Guangzhou 510515, China.
⁵ Guangdong Provincial Institute of Public Health, Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China. Electronic address: gztt_2002@163.com.

PMID: 32248024
DOI: 10.1016/j.envint.2020.105682

Abstract

Background: The placenta performs crucial functions to ensure normal fetal development. Experimental studies have indicated associations between exposure to elevated temperatures during pregnancy and reduction in placental weight and volume. However, epidemiological studies in humans are lacking.

Objective: To estimate the associations between prenatal exposure to ambient temperature with placental weight, volume, and the placental weight to birth weight ratio (PFR).

Methods: We conducted a prospective birth cohort study using the Prenatal Environment and Offspring Health Cohort (PEOH Cohort) beginning in 2016 in Guangzhou, China. Women in early pregnancy were recruited and followed up during their hospitalization for childbirth. An inverse distance-weighted method was employed to estimate the average temperature exposure of every 4 weeks as well as the trimester-specific average temperature exposure at the individual's residential address. A generalized linear model was applied to estimate the effects of temperature exposure during pregnancy on the placental weight, volume, and PFR.

Results: A total of 4051 pregnant women were enrolled. Compared with the reference temperature of 20 °C, maternal exposure to 29 °C (95th centile) during late pregnancy was associated with an average of -6.03 g (95% confidence interval [CI]: -11.28 g, -0.78 g) in placental weight, -16.15 cm³ (95% CI: -26.24 cm³, -6.07 cm³) in placental volume, and 0.26 (95% CI: 0.07, 0.45) in PFR. The peak effects of high temperatures on placental weight, volume, and PFR were found from 29 to 32 weeks (β = -3.79 g, 95% CI: -8.39 g, 0.82 g), 37 to 40 weeks (β = -19.34 cm³, 95% CI: -30.99 cm³, -7.69 cm³), and 25 to 28 weeks (β = 0.35, 95% CI: 0.04, 0.66), respectively.

Conclusions: Maternal exposure to elevated temperatures was associated with a decrease in placental weight and volume and an increase in PFR. The associations were stronger when exposures occurred during late pregnancy.

Keywords: Birth cohort study; Heat stress; Placental volume; Placental weight; Placental weight to birthweight ratio; Temperature.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Birth Weight
China
Cohort Studies
Female
Humans
Maternal Exposure* / adverse effects
Parturition*
Placenta
Pregnancy
Prospective Studies
Temperature