Background: To explore maternal pregestational and periconceptional factors associated with low birth weight in offspring and inform the development of targeted interventions.
Methods: A prospective birth cohort involving 34,104 pregnant women and their offspring was constructed. The participants were enrolled during 8-14 gestational weeks and followed up at 3 months postpartum. Modified Poisson regression with robust error variances was employed to examine the associations between low birth weight and various maternal factors, including demographics, medical history, obstetric factors, lifestyle behaviors, nutrition, and environmental exposures.
Results: The incidence of low birth weight was 8.9% (95%CI: 8.6-9.2). Maternal demographic factors, including advanced gestational age (≥ 35 years, RR = 1.14), urban residence (RR = 1.74) and a lower education level, were found to be associated with low birth weight. Pregestational medical and behavioral factors significantly increased the risk of low birth weight, including multiparity, a history of preterm birth, diseases such as tuberculosis and syphilis, and alcohol consumption (RRs: 1.71, 1.56, 2.27, 2.25, and 1.54, respectively). Additionally, periconceptional factors also significantly contributed to low birth weight, including medical factors (infections, gestational complications such as preeclampsia, a lack of folic acid supplementation; RRs: 2.36, 5.97, 1.48), nutritional factors (being underweight before conception, weight gain < 10 kg during pregnancy, imbalanced diet; RRs: 1.59, 2.42, 1.34), behavioral factors (alcohol consumption and moderate-to-high physical activity; RRs: 1.23 and 1.22), and exposure to renovation pollutants (RR = 1.21). Overall, observed modifiable risk factors accounted for 40.92% of low birth weight cases, with a greater proportion found in mothers with advanced gestational age than in those under 35 years (44.61% vs. 31.91%). Among these factors, achieving adequate weight gain during pregnancy (≥ 10 kg) could prevent 20.59% (18.68-22.45) of cases. Furthermore, the incidence of low birth weight may be effectively reduced through maintaining a balanced diet, supplementing folic acid, and avoiding excessive physical activity during pregnancy.
Conclusions: Mothers at risk for delivering low-birth-weight infants can be identified based on pregestational and periconceptional factors. This could be prevented through targeted interventions, including nutritional and behavioral measures. Tailored interventions should be prioritized by antenatal care providers.
Trial registration: The study was retrospectively registered in Chinese Clinical Trial Registry Center on 06/14/2018, registration number: ChiCTR1800016635, available at: https://www.chictr.org.cn/showproj.html?proj=28300 .
Keywords: Associated factor; Gestational complication; Gestational nutrition; Lifestyle behavior; Low birth weight; Population attributable fraction; Preterm birth.
© 2025. The Author(s).