• Caesarean;
  • caseload midwifery;
  • continuity of care;
  • randomised controlled trial

Please cite this paper as: McLachlan H, Forster D, Davey M, Farrell T, Gold L, Biro M, Albers L, Flood M, Oats J, Waldenström U. Effects of continuity of care by a primary midwife (caseload midwifery) on caesarean section rates in women of low obstetric risk: the COSMOS randomised controlled trial. BJOG 2012;119:1483–1492.

Objective  To determine whether primary midwife care (caseload midwifery) decreases the caesarean section rate compared with standard maternity care.

Design  Randomised controlled trial.

Setting  Tertiary-care women’s hospital in Melbourne, Australia.

Population  A total of 2314 low-risk pregnant women.

Methods  Women randomised to caseload received antenatal, intrapartum and postpartum care from a primary midwife with some care by ‘back-up’ midwives. Women randomised to standard care received either midwifery or obstetric-trainee care with varying levels of continuity, or community-based general practitioner care.

Main outcome measures  Primary outcome: caesarean birth. Secondary outcomes included instrumental vaginal births, analgesia, perineal trauma, induction of labour, infant admission to special/neonatal intensive care, gestational age, Apgar scores and birthweight.

Results  In total 2314 women were randomised–1156 to caseload and 1158 to standard care. Women allocated to caseload were less likely to have a caesarean section (19.4% versus 24.9%; risk ratio [RR] 0.78; 95% CI 0.67–0.91; P = 0.001); more likely to have a spontaneous vaginal birth (63.0% versus 55.7%; RR 1.13; 95% CI 1.06–1.21; P < 0.001); less likely to have epidural analgesia (30.5% versus 34.6%; RR 0.88; 95% CI 0.79–0.996; P = 0.04) and less likely to have an episiotomy (23.1% versus 29.4%; RR 0.79; 95% CI 0.67–0.92; P = 0.003). Infants of women allocated to caseload were less likely to be admitted to special or neonatal intensive care (4.0% versus 6.4%; RR 0.63; 95% CI 0.44–0.90; P = 0.01). No infant outcomes favoured standard care.

Conclusion  In settings with a relatively high baseline caesarean section rate, caseload midwifery for women at low obstetric risk in early pregnancy shows promise for reducing caesarean births.