Critical Threshold of Average Weekly Weight Gain in Overweight Pregnant Women During the Second and Third Trimesters: A Strategy to Prevent Macrosomia

Yaxin Wang,1 Ziyang Wang,2 Yin Sun,1 Lin Yang,2 Liangkun Ma,1 Jiao Li,2 Suhan Zhang,1 Xuanjin Yang1 1Department of Obstetrics and Gynecology, National Clinical Research Center for Obstetric & Gynecologic Diseases, PUMC Hospital, CAMS and PUMC, Beijing, People’s Republic of China; 2Institute of Medical Information/Medical Library, Chinese Academy of Medical Science & Peking Union Medical College, Beijing, 100020, People’s Republic of ChinaCorrespondence: Yin Sun, Peking Union Medical College Hospital, 1 Shuaifuyuan, Dongcheng District, Beijing, People’s Republic of China, Email [email protected]: The study aimed to obtain more evidence on the association of gestational weight gain and pre-pregnancy body mass index (BMI) with macrosomia.Methods: The data on 5409 live births delivered at Peking Union Medical College Hospital from July 2020 to June 2022 were collected. Group analyses were performed according to the presence or absence of macrosomia. Multivariable binary logistic regression and incidence heatmaps was used to analyze the related factors of macrosomia.Results: The following variables were significantly associated with macrosomia: overweight (odds ratio [OR]: 2.24, 95% confidence interval [CI]: 1.62– 3.10), obesity (OR: 4.56, 95% CI: 2.93– 6.98), excessive gestational weight gain (OR: 2.39, 95% CI: 1.67– 3.43), gestational age at delivery at 39– 41 weeks (OR: 3.83, 95% CI: 2.56– 5.95), gestational age at delivery over 41 weeks (OR: 7.88, 95% CI: 4.37– 14.19), education level of junior college or below (OR: 1.95, 95% CI: 1.19– 3.09), and multipara (OR: 1.62, 95% CI: 1.09– 2.42). “v” represents the mean weekly weight gain during the second and third trimesters. A higher v value increased the risk of macrosomia by 2.6-fold (95% CI: 1.37– 4.89, P = 0.003). Compared to normal weight women, after adjustment for different pre-pregnancy BMI subgroups, overweight pregnant women had higher weekly weight gain in the second and third trimesters (OR: 4.57, 95% CI: 2.27– 9.10, P < 0.001). Obese pregnant women had higher average weekly weight gain during the second and third trimesters, and the OR value for macrosomia was 11.33 (95% CI: 4.95– 25.18, P < 0.001). To reduce the incidence of macrosomia in overweight pregnant women, v = 0.32 could be considered the critical threshold of average weekly weight gain in these women in the second and third trimesters of pregnancy.Conclusion: Pre-pregnancy BMI and weight gain during pregnancy are closely related to macrosomia. The introduction of average weekly weight gain values in the second and third trimesters of pregnancy probably help pregnant women minimizing adverse pregnancy-related outcomes.Plain Language Summary: What is already known about this topic?Pre-pregnancy BMI and GWG are both risk factors for macrosomia. It is very important to develop effective interventions based on pathogenic factors to promote the health of mothers and children. However, the threshold for maternal weight control in the second and third trimesters of pregnancy is unclear.What is added by this report?Our data suggest that the critical threshold of average weekly weight gain in overweight pregnant women during the second and third trimesters 0.32kg per week is beneficial to reduce the incidence of macrosomia.What are the implications for public health practice?The results of this study highlight the importance of weight management in women in the second and third trimesters, especially those who are overweight, and reasonable control of weight gain will contribute to maternal and fetal health.Keywords: pregnancy, pre-pregnancy BMI, gestational weight gain, macrosomia, critical threshold of weight gain