A retrospective cohort study of the association between midwifery experience and perinatal mortality

Objective To determine whether experience of midwife‐only and nurse‐midwife lead maternity carers (LMCs) is related to perinatal mortality. Methods In a retrospective analysis, routinely collected data were obtained for all pregnancies resulting in live births (or stillbirth at ≥ 20 weeks or weighing > 400 g) in New Zealand in 2005–2009. An anonymized dataset of date of midwife registration was used. The main outcome measure was perinatal mortality (fetal deaths and neonatal deaths ≤ 27 days). Results Among 233 215 eligible births, 84 043 were linked to a midwife‐only LMC and 150 172 to a nurse‐midwife LMC. Among pregnancies with midwife‐only LMCs, perinatal mortality was higher when the midwife had less than 1 year of experience than when the midwife had 5–9 years’ experience (rate ratio 1.33; 95% confidence interval 1.02–1.73), an absolute difference of two additional deaths per 1000 births. There was a decreasing rate of perinatal mortality with increasing experience ( P = 0.031). Perinatal mortality rates did not differ by experience in the nurse‐midwife group. Conclusion Pregnancies cared for by early‐career (< 1 year) midwife‐only LMCs were associated with a 33% increase in perinatal mortality. No association between experience and perinatal mortality was found for nurse‐midwives. Midwife‐only trained LMCs could require additional training and/or supervision in their first year of practice.