The increased incidence of macrosomia has caused an enormous burden after the transition from the almost 40-year one-child policy to the universal two-child policy in 2015 and further to the three-child policy in 2021 in China. However, studies on risk factors of macrosomia in multipara under the new fertility policy in China are limited. We aim to explore the incidence and risk factors for macrosomia in multipara to provide the scientific basis for preventing macrosomia in multipara. A multi-center retrospective study was conducted among 6200 women who had two consecutive deliveries in the same hospital and their second newborn was delivered from January to October 2018 at one of 18 hospitals in 12 provinces in China. Macrosomia was defined as birth weight ≥ 4000 g. Logistic regression models were performed to analyze risk factors for macrosomia in multipara. The incidence of macrosomia in multipara was 7.6% (470/6200) and the recurrence rate of macrosomia in multipara was 27.2% (121/445). After adjusting for potential confounders, a higher prepregnancy BMI, higher gestational weight gain, history of macrosomia, a longer gestation in the subsequent pregnancy were independent risk factors of macrosomia in multipara (p < 0.05). Healthcare education and preconception consultation should be conducted for multipara patients with a history of macrosomia to promote maintaining optimal prepregnancy BMI and avoid excessive gestational weight gain to prevent macrosomia.
