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Wu Y, Ye H, Yuan Y, Kong C, Jing W, Liu J, Liu M. Association between season of conception, month of conception with preterm birth in China: a population-based retrospective cohort study. Reprod Health 2023; 20:88. [PMID: 37312160 DOI: 10.1186/s12978-023-01636-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 06/05/2023] [Indexed: 06/15/2023] Open
Abstract
BACKGROUND Seasonal patterns of preterm birth were identified in previous studies, but the effect of conception season on preterm birth has not been extensively studied. Based on the notion that the etiological roots of preterm birth lie in the beginning of pregnancy, we did a population-based retrospective cohort study in Southwest China to examine the effects of season of conception and month of conception on preterm birth. METHODS We did a population-based retrospective cohort study in women (aged 18-49) who participated in the NFPHEP from 2010 to 2018, and had a singleton livebirth in southwest China. According to the time of the last menstruation reported by the participants, month of conception and season of conception were then ascertained. We used multivariate log-binomial model to adjust the potential risk factors for preterm birth and obtained adjusted risk ratio (aRR) and 95% confidence intervals (95%CI) for conception season, conception month and preterm birth. RESULTS Among 194 028 participants, 15 034 women had preterm birth. Compared with pregnancies that were conceived in the summer, pregnancies that were conceived in the spring, autumn and winter had the higher risk of preterm birth (Spring: aRR = 1.10, 95% CI: 1.04-1.15; Autumn: aRR = 1.14, 95% CI: 1.09-1.20; Winter: aRR = 1.28, 95% CI: 1.22-1.34) and also had a higher risk of early preterm birth (Spring: aRR = 1.09, 95% CI: 1.01-1.18; Autumn: aRR = 1.09, 95% CI: 1.01-1.19; Winter: aRR = 1.16, 95% CI: 1.08-1.25). Pregnancies in December, and January had a higher risk of preterm birth and early preterm birth than pregnancies that were conceived in July. CONCLUSIONS Our study found that preterm birth was significantly related to season of conception. Preterm and early preterm birth rates were the highest among pregnancies that were conceived in winter, and the lowest among pregnancies in summer.
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Affiliation(s)
- Yu Wu
- Department of Epidemiology and Biostatics, School of Public Health, Peking University, No. 38, Xueyuan Road, Haidian District, Beijing, 100191, People's Republic of China
| | - Hanfeng Ye
- Yunnan Population and Family Planning Research Institute, No. 146, Qingnian Road, Wuhua District, Kunming, 650021, Yunnan, China
| | - Yanling Yuan
- Yunnan Population and Family Planning Research Institute, No. 146, Qingnian Road, Wuhua District, Kunming, 650021, Yunnan, China
| | - Cai Kong
- Yunnan Population and Family Planning Research Institute, No. 146, Qingnian Road, Wuhua District, Kunming, 650021, Yunnan, China
| | - Wenzhan Jing
- Department of Epidemiology and Biostatics, School of Public Health, Peking University, No. 38, Xueyuan Road, Haidian District, Beijing, 100191, People's Republic of China
| | - Jue Liu
- Department of Epidemiology and Biostatics, School of Public Health, Peking University, No. 38, Xueyuan Road, Haidian District, Beijing, 100191, People's Republic of China
| | - Min Liu
- Department of Epidemiology and Biostatics, School of Public Health, Peking University, No. 38, Xueyuan Road, Haidian District, Beijing, 100191, People's Republic of China.
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Zheng X, Zhang W, Lu C, Norbäck D, Deng Q. An epidemiological assessment of the effect of ambient temperature on the incidence of preterm births: Identifying windows of susceptibility during pregnancy. J Therm Biol 2018; 74:201-207. [PMID: 29801628 DOI: 10.1016/j.jtherbio.2018.04.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/31/2018] [Accepted: 04/03/2018] [Indexed: 01/07/2023]
Abstract
It is well known that exposure to thermal stress during pregnancy can lead to an increased incidence of premature births. However, there is little known regarding window(s) of susceptibility during the course of a pregnancy. We attempted to identify possible windows of susceptibility in a cohort study of 3604 children in Changsha with a hot-summer and cold winter climatic characteristics. We examined the association between PTB and ambient temperature during different timing windows of pregnancy: conception month, three trimesters, birth month and entire pregnancy. We found a U-shaped relation between the prevalence of PTB and mean ambient temperature during pregnancy. Both high and low temperatures were associated with PTB risk, adjusted OR (95% CI) respectively 2.57 (1.98-3.33) and 2.39 (1.93-2.95) for 0.5 °C increase in high temperature range (>18.2°C) and 0.5°C decrease in low temperature range (< 18.2°C). Specifically, PTB was significantly associated with ambient temperature and extreme heat/cold days during conception month and the third trimester. Sensitivity analysis indicated that female fetus were more susceptible to the risk of ambient temperature. Our study indicates that the risk of preterm birth due to high or low temperature may exist early during the conception month.
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Affiliation(s)
- Xiangrong Zheng
- Department of Pediatrics, XiangYa Hospital, Central South University, Changsha, China
| | - Weishe Zhang
- Department of Obstetrics, XiangYa Hospital, Central South University, Changsha, China
| | - Chan Lu
- School of Energy Science and Engineering, Central South University, Changsha, China
| | - Dan Norbäck
- School of Energy Science and Engineering, Central South University, Changsha, China; Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Qihong Deng
- School of Energy Science and Engineering, Central South University, Changsha, China; XiangYa School of Public Health, Central South University, Changsha, China; Center for Environment and Water Resources, Central South University, Changsha, China.
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