Midwife annual delivery workload and maternal and neonatal adverse outcomes, is there an association?

In recent years there has been growing interest in the relationship between the workload of an individual practitioner and its short- and long-term consequences on birth outcomes. In this respect, data is limited with regard to midwives' workload. We aimed to evaluate the association between midwives' annual birth workload and the short-term, adverse maternal and neonatal outcomes occurring at birth.

This retrospective cohort study was performed in a single tertiary academic center between 2006 and 2018. All single, live vertex term vaginal births were included and categorized into two groups based on the midwife's median annual volume of births during the study duration. The "high-volume" and "low-volume" groups included births above and below the median annual volume, respectively as a dichotomous variable. Further analyses were performed for the annual volume by deciles. Short term maternal and neonatal outcomes were compared between groups and between deciles.

During the study period 140,856 births met the study criteria. The median annual volume of births of a single midwife was 152 [114-195]. Maternal and labor characteristics were comparable between the groups. Maternal outcomes were not significantly associated with the midwifes' annual workload. However, neonates delivered by midwives with "low" annual volume had higher rate of neonatal jaundice (aOR 1.07, 95 % CI [1.00-1.14]) and mechanical ventilation (aOR 1.32, 95 % CI [1.05-1.66).

Adverse perinatal outcomes are only mildly affected by midwives' annual volume after controlling for the midwife, parturient and neonate's characteristics.