Maternal body mass index in early pregnancy and offspring mortality up to early adulthood: A nationwide cohort study
4 affiliations
- 1MOE-Shanghai Key Laboratory of Children’s Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- 2Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden
- 3Department of Maternal and Child Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- 4Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
Abstract
Background: Obesity is increasingly common among women of childbearing age worldwide. Maternal obesity during pregnancy may have long-term implications for offspring health, but its association with offspring mortality remains not well understood. In this nationwide cohort study, we examined the associations of maternal body mass index (BMI) in early pregnancy with all-cause and cause-specific mortality in offspring. Methods and findings: We included 2,606,684 live births in Sweden during 1982–2014 (except for 1990 and 1991) and followed them from birth until death, emigration from Sweden, or December 31, 2023, whichever came first. Information on maternal BMI during early pregnancy was obtained from the Medical Birth Register and was categorized as: underweight (BMI <18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), obesity grade I (30.0–34.9 kg/m2), obesity grade II (35.0–39.9 kg/m2), and obesity grade III (≥40.0 kg/m2). Data on all-cause and cause-specific mortality in offsprings were obtained from the Cause of Death Register. Cox proportional hazard models were performed to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) for offspring mortality according to maternal BMI (both as a continuous and as a categorical variable), adjusting for maternal characteristics (age, education, and income at the childbirth, marital status, country of birth, smoking status in early pregnancy, psychiatric disorders and cardiovascular diseases before the childbirth). We used cousin comparison analysis to explore the potential influence of familial confounding factors. During a median follow-up of 22.4 years (interquartile range 14.9–30.7 years), 21,981 (0.8%) offspring died. Maternal BMI was positively associated with all-cause mortality in offspring: HR 1.03 (95% CI [1.02, 1.03]; p < 0.001) per 1 unit increase in BMI. Offspring of mothers with overweight or obesity (regardless of grade) during early pregnancy had higher risks of all-cause mortality than their counterparts with normal maternal BMI at the reference category; the corresponding HRs were HR 1.11 (95% CI [1.07, 1.15]; p < 0.001) for overweight, HR 1.27 (95% CI [1.20, 1.35]; p < 0.001) for obesity grade I, HR 1.68 (95% CI [1.52, 1.86]; p < 0.001) for obesity grade II, and HR 1.92 (95% CI [1.59, 2.33]; p < 0.001) for obesity grade III, respectively. The associations were similar for several of the most common underlying causes of death in young age, i.e., respiratory diseases, cardiovascular diseases, and congenital anomalies. The associations were attenuated but remained in the cousin comparison analysis. The main limitation was the potential for residual confounding; the observed associations should not be interpreted as evidence of a causal effect of maternal BMI in early pregnancy on offspring mortality. Conclusions: Offspring born to mothers with overweight or obesity during early pregnancy had an increased risk of premature mortality up to early adulthood. Given the rising obesity rate in women of childbearing age, our findings underscore the need to better understand the underlying mechanisms for this association. If confirmed by further studies, these results highlight the importance of achieving a healthy maternal BMI prior to conception as a potential strategy to improve child health. Why was this study done?: What did the researchers do and find?: What do these findings mean?: In this nationwide Swedish cohort study, Hui Wang and colleagues found that higher maternal BMI in early pregnancy was associated with a greater risk of offspring mortality from birth through early adulthood, including deaths related to respiratory and cardiovascular diseases and congenital anomalies.
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BibTeX
@article{wang2026maternal,
title = {{Maternal body mass index in early pregnancy and offspring mortality up to early adulthood: A nationwide cohort study}},
author = {Hui Wang and Hua Chen and Jette Möller and Yajun Liang and Krisztina D. László},
journal = {PLOS Medicine},
year = {2026},
month = sep,
doi = {10.1371/journal.pmed.1005217},
url = {https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005217},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Maternal body mass index in early pregnancy and offspring mortality up to early adulthood: A nationwide cohort study
AU - Hui Wang
AU - Hua Chen
AU - Jette Möller
AU - Yajun Liang
AU - Krisztina D. László
PY - 2026
DA - 2026/09/01
JO - PLOS Medicine
DO - 10.1371/journal.pmed.1005217
UR - https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005217
AB - Background: Obesity is increasingly common among women of childbearing age worldwide. Maternal obesity during pregnancy may have long-term implications for offspring health, but its association with offspring mortality remains not well understood. In this nationwide cohort study, we examined the associations of maternal body mass index (BMI) in early pregnancy with all-cause and cause-specific mortality in offspring. Methods and findings: We included 2,606,684 live births in Sweden during 1982–2014 (except for 1990 and 1991) and followed them from birth until death, emigration from Sweden, or December 31, 2023, whichever came first. Information on maternal BMI during early pregnancy was obtained from the Medical Birth Register and was categorized as: underweight (BMI <18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), obesity grade I (30.0–34.9 kg/m2), obesity grade II (35.0–39.9 kg/m2), and obesity grade III (≥40.0 kg/m2). Data on all-cause and cause-specific mortality in offsprings were obtained from the Cause of Death Register. Cox proportional hazard models were performed to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) for offspring mortality according to maternal BMI (both as a continuous and as a categorical variable), adjusting for maternal characteristics (age, education, and income at the childbirth, marital status, country of birth, smoking status in early pregnancy, psychiatric disorders and cardiovascular diseases before the childbirth). We used cousin comparison analysis to explore the potential influence of familial confounding factors. During a median follow-up of 22.4 years (interquartile range 14.9–30.7 years), 21,981 (0.8%) offspring died. Maternal BMI was positively associated with all-cause mortality in offspring: HR 1.03 (95% CI [1.02, 1.03]; p < 0.001) per 1 unit increase in BMI. Offspring of mothers with overweight or obesity (regardless of grade) during early pregnancy had higher risks of all-cause mortality than their counterparts with normal maternal BMI at the reference category; the corresponding HRs were HR 1.11 (95% CI [1.07, 1.15]; p < 0.001) for overweight, HR 1.27 (95% CI [1.20, 1.35]; p < 0.001) for obesity grade I, HR 1.68 (95% CI [1.52, 1.86]; p < 0.001) for obesity grade II, and HR 1.92 (95% CI [1.59, 2.33]; p < 0.001) for obesity grade III, respectively. The associations were similar for several of the most common underlying causes of death in young age, i.e., respiratory diseases, cardiovascular diseases, and congenital anomalies. The associations were attenuated but remained in the cousin comparison analysis. The main limitation was the potential for residual confounding; the observed associations should not be interpreted as evidence of a causal effect of maternal BMI in early pregnancy on offspring mortality. Conclusions: Offspring born to mothers with overweight or obesity during early pregnancy had an increased risk of premature mortality up to early adulthood. Given the rising obesity rate in women of childbearing age, our findings underscore the need to better understand the underlying mechanisms for this association. If confirmed by further studies, these results highlight the importance of achieving a healthy maternal BMI prior to conception as a potential strategy to improve child health. Why was this study done?: What did the researchers do and find?: What do these findings mean?: In this nationwide Swedish cohort study, Hui Wang and colleagues found that higher maternal BMI in early pregnancy was associated with a greater risk of offspring mortality from birth through early adulthood, including deaths related to respiratory and cardiovascular diseases and congenital anomalies.
SN - 1549-1676
ER -