Vacuum extraction in fetal macrosomia and risk of neonatal complications: a population-based cohort study

Introduction. High birthweight is associated with complicated childbirth. The aim of the present study was to investigate the association between birthweight, mode of delivery, and neonatal complications among infants born at term with a birthweight >= 3000 g. Material and methods. This population-based cohort study used data from the Swedish Medical Birth Register from 1999 to 2012, including 1 030 775 births at >36 completed weeks. Exposure was mode of delivery, categorized into non-instrumental vaginal delivery (VD), emergency cesarean section (CS), vacuum extraction (VE) or cesarean section following attempted vacuum extraction (VE + CS), and birthweight was divided into five categories (3000-3999 g, 4000-4499 g, 4500-4999 g, and >= 5000 g). The following outcomes were assessed: 5-min Apgar score <7, neonatal convulsions, intracranial hemorrhage, and brachial plexus injury. Infants born after VD with a birthweight of 3000-3999 g were used as reference in the logistic regression analysis. Results. The odds ratios for all complications increased at higher birthweights among infants born after VE/VE + CS and VD. The highest risks were seen after VE/VE + CS with an adjusted odds ratio for neonatal convulsions of 2.6 (95% CI 2.1-3.2) in the reference birthweight group and 6.3 (95% CI 4.3-9.2) among infants with a birthweight of >= 4500 g. The corresponding adjusted odds ratios for intracranial hemorrhage were 2.6 (95% CI 1.7-3.9) and 6.7 (95% CI 3.3-13.6) and for brachial plexus injury 4.0 (95% CI 3.3-4.9) and 88.4 (95% CI 71.9-108.4). Conclusion. Vacuum extraction is a risk factor for serious neonatal complications, in particular when used in macrosomic fetuses.