Instrumental vaginal deliveries: are midwives safer practitioners? A retrospective cohort study

Objective: To compare obstetric morbidity of midwife-performed instrumental vaginal deliveries with those performed by doctors.

Design: Retrospective cohort study.

Setting: University Hospital, UK.

Population: Women undergoing an instrumental vaginal delivery of a singleton infant outside of the operating theater in Aberdeen Maternity Hospital, between June 2005 and June 2010.

Methods: Prospectively entered data were obtained from the hospital data management system. Obstetric outcomes of deliveries by midwives were compared with those performed by any doctor and, in a secondary analysis, with those by junior doctors (fewer than two years at registrar' level). Sociodemographic characteristics and clinical outcomes were compared using the chi-squared test, Mann-Whitney U-test and independent sample t-test.

Main outcome measures: Third- or fourth-degree tears.

Results: Among 2540 women identified, 330 (13%) were delivered by midwives. Maternal and clinical characteristics were comparable in each group. Midwives were more likely to use ventouse as their instrument of choice. Women delivered by midwives were less likely to suffer a third- or fourth-degree tears than those delivered by doctors and junior doctors. This difference did not reach statistical significance once adjusted for instrument used: odds ratio 0.6 (95% confidence interval: 0.3-1.2) and odds ratio 0.6 (95% confidence interval: 0.3-1.1), respectively.

Conclusions: Instrumental vaginal deliveries performed by trained midwives are associated with equivalent maternal morbidity to those performed by doctors once adjusted for midwives' preference for the ventouse. This study highlights the potential contribution of an advanced role for midwives in the labor ward.