Risk Factors and Pregnancy Outcomes of Macrosomia: a Retrospective Cohort Study

Abstract

Objectives: To evaluate maternal risk factors associated with macrosomia (birthweight ≥4000 g), and perinatal outcomes in Hong Kong.
Methods: This was a retrospective cohort study conducted at a regional obstetric unit over a 5-year period. All singleton pregnancies with livebirths delivered at term (≥37 weeks of gestation) were analysed. Maternal epidemiological and anthropometric characteristics, presence of antenatal complications (gestational diabetes and medical disorders), and pregnancy outcomes (need for labour induction, mode of delivery, Apgar scores, occurrence of shoulder dystocia, and birth trauma) were compared between macrosomic and non-macrosomic pregnancies. Logistic regression analysis was conducted to identify risk factors associated with macrosomia.
Results: From 2012 to 2016, 19 614 singleton, term livebirths were identified. Of these, 567 (2.89%) babies had a birthweight of ≥4000 g. A logistic regression model confirmed that the most prominent risk factor for macrosomia was post-term pregnancy (adjusted odds ratio [OR]=4.80), followed by diabetic complications in pregnancy (adjusted OR=3.90), maternal obesity (adjusted OR=1.65), multiparity (adjusted OR=1.50), and previous miscarriages (adjusted OR=1.35). Women with macrosomic pregnancy were more likely to be delivered by Caesarean section (36.0% vs. 20.8%), have failed instrumental deliveries (11.10% vs. 4.18%), have wound complications (1.23% vs. 0.23%), and experience postpartum haemorrhage (16.60% vs. 6.48%). Macrosomic neonates were more likely to encounter shoulder dystocia (5.23% vs. 0.40%) and birth trauma (0.50% vs. 0.05%).
Conclusion: The incidence of macrosomic pregnancy in this local population (2.89%) was significantly lower than that reported in western populations. Our data confirm an increased likelihood of maternal and neonatal morbidities in these pregnancies.