Open Access Open Badges Study protocol

COSMOS: COmparing Standard Maternity care with One-to-one midwifery Support: a randomised controlled trial

Helen L McLachlan12*, Della A Forster13, Mary-Ann Davey14, Judith Lumley1, Tanya Farrell3, Jeremy Oats3, Lisa Gold5, Ulla Waldenström6, Leah Albers7 and Mary Anne Biro1

Author Affiliations

1 Mother and Child Health Research, La Trobe University, 324-328 Little Lonsdale St, Melbourne, Australia

2 Division of Nursing and Midwifery, La Trobe University, Bundoora, Australia

3 Royal Women's Hospital, Locked Bag 300, Grattan St and Flemington Rd, Parkville, Australia

4 Consultative Council on Obstetric and Paediatric Mortality and Morbidity, Department of Human Services, 50 Lonsdale St, Melbourne, Australia

5 Health Economics Unit, School of Health and Social Development, Deakin University, 221 Burwood Highway, Burwood, Australia

6 Department of Nursing, Karolinska Institutet, Stockholm, Sweden

7 College of Nursing, University of New Mexico, Albuquerque, New Mexico

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BMC Pregnancy and Childbirth 2008, 8:35  doi:10.1186/1471-2393-8-35

Published: 5 August 2008



In Australia and internationally, there is concern about the growing proportion of women giving birth by caesarean section. There is evidence of increased risk of placenta accreta and percreta in subsequent pregnancies as well as decreased fertility; and significant resource implications. Randomised controlled trials (RCTs) of continuity of midwifery care have reported reduced caesareans and other interventions in labour, as well as increased maternal satisfaction, with no statistically significant differences in perinatal morbidity or mortality. RCTs conducted in the UK and in Australia have largely measured the effect of teams of care providers (commonly 6–12 midwives) with very few testing caseload (one-to-one) midwifery care. This study aims to determine whether caseload (one-to-one) midwifery care for women at low risk of medical complications decreases the proportion of women delivering by caesarean section compared with women receiving 'standard' care. This paper presents the trial protocol in detail.


A two-arm RCT design will be used. Women who are identified at low medical risk will be recruited from the antenatal booking clinics of a tertiary women's hospital in Melbourne, Australia. Baseline data will be collected, then women randomised to caseload midwifery or standard low risk care. Women allocated to the caseload intervention will receive antenatal, intrapartum and postpartum care from a designated primary midwife with one or two antenatal visits conducted by a 'back-up' midwife. The midwives will collaborate with obstetricians and other health professionals as necessary. If the woman has an extended labour, or if the primary midwife is unavailable, care will be provided by the back-up midwife. For women allocated to standard care, options include midwifery-led care with varying levels of continuity, junior obstetric care and community based general medical practitioner care. Data will be collected at recruitment (self administered survey) and at 2 and 6 months postpartum by postal survey. Medical/obstetric outcomes will be abstracted from the medical record. The sample size of 2008 was calculated to identify a decrease in caesarean birth from 19 to 14% and detect a range of other significant clinical differences. Comprehensive process and economic evaluations will be conducted.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN012607000073404.