Inter-delivery birthweight difference greater than 1000 grams and its effects on maternal and neonatal outcomes.

To examine the association between actual birth weight difference of more than 1000 g between the second and first delivery and short-term maternal and neonatal outcomes including mode of delivery. Retrospective database cohort study of single large academic center, between the years 2005 and 2019. Study population included all women who had their first and second live fetus singleton delivery in our center. Women who had cesarean delivery at first delivery were excluded. Primary outcome was mode of delivery in second delivery. Secondary outcomes were composite adverse maternal and neonatal outcomes. Univariate analysis was followed by multivariate logistic regression. A total of 22,751 women were included. Of those, 316 (1.4%) gave birth to neonates with inter-delivery birth weight interval ≥1000 g from their first delivery. Women in the study group had higher rates of Oxytocin augmentation of labor, longer first and second stages of labor, episiotomy, vacuum extraction, shoulder dystocia and 1-min Apgar score ≤7. Cesarean delivery was more prevalent among the study group (7.9% vs 3.2%, aOR 3.31 [1.78-6.17], Birth weight interval ≥1000 g is associated with higher rates of cesarean deliveries, as well as an increase in maternal and neonatal adverse outcomes, making it worthwhile to screen women for significant birth weight differences.