Objective: To investigate trends in low 5-minute Apgar scores in (near) term singletons. Design: Nationwide cohort study. Setting: The Netherlands. Population: A cohort of 1,583,188 singletons liveborn between 35 +0 and 42 +6 weeks of gestation in the period 2010-2019 from the Dutch Perinatal Registry. Methods: We studied trends using Cochrane-Armitage trend tests. Risk factors were studied by logistic regression analysis and Population Attributable Risk (PAR) calculation. Main outcome measures: Low 5-minute Apgar score (<7 and <4) as primary outcome. Results: The proportion of infants with low 5-minute Apgar score <7 and <4 increased significantly between 2010 and 2019 (1.04-1.42% (p<0.001), 0.17-0.19% (p=0.009), respectively). While neonatal mortality remained unchanged, NICU admissions and low umbilical artery pH’s increased significantly. Many perinatal characteristics showed a significant association with low Apgar scores. The highest risks were found for nulliparity, epidural analgesia, emergency caesarean section, instrumental vaginal delivery, prolonged second stage of labour, male sex and delivery in secondary care. The obstetric interventions induction of labour, epidural analgesia and planned caesarean section showed an increasing trend. Instrumental vaginal delivery and emergency caesarean section were performed less frequently over time, however within these obstetric intervention subgroups the highest increase in low Apgar scores was observed. Conclusions In the Netherlands, the risk of a low 5-minute Apgar score increased significantly over the last decade, with the highest increase being observed in the obstetric intervention subgroups of instrumental vaginal delivery and emergency caesarean section. Neonatal mortality remained stable over the study period.

Objective To assess background rates of adverse pregnancy outcomes before implementation of a maternal pertussis immunisation programme in the Netherlands, to put into perspective the safety concerns about such outcomes following immunisation. Design Retrospective cross-sectional study. Setting and population Dutch pregnant women and their infants who were registered in the Dutch Perinatal Registry in the 2006-2018 period. Births of ≥500g birth weight and ≥24+0w gestational age were included. Methods Annual numbers of adverse outcomes were used to calculate incidence rates per 10,000. Trends with moving-average-lines over the past 3 years were plotted, with 95% confidence interval. Main Outcome Measures Adverse outcomes at maternal and neonatal level. Results From 2006 through 2018, yearly numbers of pregnancies ranged between 158,868-175,710. Numbers of newborns ranged between 161,307-178,874, of whom 160,838-178,177 were live-born. Most outcomes were stable over time. Between 2006-2011, occurrence of labour induction increased by 68%, and postpartum hemorrhage increased by 25%. Both stabilised from 2011 onwards. Perinatal mortality up to day 7 or 28 postpartum decreased by 38% and 37%, respectively. Occurrence of low Apgar score among preterm infants born before 37+0w gestational age and among term infants increased by 19% and 27%, respectively. Conclusions Our study on background incidences showed notable increases over time in occurrence of labour induction, postpartum hemorrhage and low Apgar score, while showing a considerable decrease in overall perinatal mortality. These findings should be considered when interpreting data on adverse events occurring since Tdap vaccination was implemented.