The impact of increased number of low-risk deliveries on maternal and neonatal outcomes: A retrospective cohort study in Finland in 2011-2015.

Objectives: Our aim was to demonstrate the influence of increased number of low-risk deliveries on obstetric and neonatal outcome.

Study Design: The study hospital was Kätilöopisto Maternity Hospital in Helsinki. Simultaneously, we studied all three delivery units in the Helsinki region in the population-based analysis. The study population was singleton hospital deliveries occurring between 2011 and 2012, and 2014-2015. The study hospital included 11 237 and 15 637 births and the population-based group included 28 950 and 27 979 births. We compared outcome measures in different periods by calculating adjusted odds ratios (AOR). Main outcome measures were induced delivery, mode of delivery, third or fourth degree perineal tear, Apgar score at five minutes <7, umbilical artery pH <7.00, transfer to higher level of neonatal care, neonatal antibiotic treatment, respiratory support of the neonate, hospitalization of the neonate >7 days, and perinatal death.

Results: In the study hospital, induction rate increased from 22.4% to 24.8% (AOR 1.06, 95% CI; 1.00-1.12) while in the population-based analysis the rate decreased from 22.2% to 21.5% (AOR 0.96, 95% CI; 0.92-1.00). Percentage of neonatal transfers, low Apgar scores, and severe perineal tears increased both in study hospital and in population-based group. Changes in operative delivery rate and other adverse perinatal outcomes were statistically insignificant.

Conclusions: Increasing the volume of a delivery unit does not compromise maternal or neonatal outcome. Specific characteristics of a delivery unit affect the volume outcome association.