Mothers using autonomously practicing midwives throughout their pregnancy and childbirth are more likely to have adverse outcomes for their newborns than those who use obstetricians, according to a retrospective study of nearly a quarter million babies born in New Zealand published in PLOS Medicine by Ellie Wernham of University of Otago, New Zealand, and colleagues.
In 1990, New Zealand adopted a midwife-led model of maternity care, giving midwives the ability to practice autonomously and be fully reimbursed by the government, offering patients free care. As a result, more than four out of five New Zealand mothers use midwives throughout pregnancy and delivery, with doctors generally only getting involved when there are risk factors. Wernham and colleagues examined data on all 244,047 full-term births, with no major fetal or neonatal congenital, chromosomal, or metabolic abnormalities, that occurred in New Zealand over the five years spanning 2008 through 2012 and compared adverse outcomes for newborns born to mothers under midwife-led care to outcomes with doctor-led care at first registration. The outcomes included oxygen deprivation during delivery, an infant's size, stillbirths, mortality, and neonatal encephalopathy - a condition that can result in brain injury, as well as Apgar scores - a measure of infant well-being immediately after delivery.
Compared with the midwife-led model and after adjusting for demographics, socioeconomic factors, and pre-existing conditions, the researchers observed lower odds of some adverse birth outcomes when maternity care was managed medically, including 55 percent (95% confidence intervals [CI] 0.32-0.62) lower odds of birth related asphyxia, 39 percent (95% CI 0.38-0.97) lower odds of neonatal encephalopathy, and 48 percent (95% CI 0.43-0.64) lower odds of a low Apgar score at five minute after delivery. There were no significant differences between the midwife-led and doctor-led births for neonatal mortality and intrauterine hypoxia. The study was limited by the lack of data on adverse events for mothers, its retrospective design, and that the demographics - while adjusted for - were different in the two groups.
The authors say: "Despite New Zealand having overall internationally comparable maternity outcomes, the findings of this study suggest that avoidable adverse outcomes may still be occurring."
In an accompanying Perspective, Ank de Jonge and Jane Sandall discuss the discrepancy between the new study and a 2016 Cochrane systematic review that found no increase in adverse events with midwife care. Differences in both how the study was conducted - such as how adverse events were detected - as well as how midwife care is organized in New Zealand compared to other countries are the most likely explanations, they say, adding that "multi-disciplinary research is required to understand mechanisms leading to differences in processes, outcomes, costs, and women's experiences between midwife-led continuity of care and other models of care."
The authors received no specific funding for this work.
The authors have declared that no competing interests exist.
Article: A Comparison of Midwife-Led and Medical-Led Models of Care and Their Relationship to Adverse Fetal and Neonatal Outcomes: A Retrospective Cohort Study in New Zealand, Wernham E, Gurney J, Stanley J, Ellison-Loschmann L, Sarfati D, PLOS Medicine, doi:10.1371/journal.pmed.1002134, published 27 September 2016.
Perspective: Improving Research into Models of Maternity Care to Inform Decision Making, de Jonge A, Sandall J, PLOS Medicine, doi:10.1371/journal.pmed.1002135, published 27 September 2016.
JS is lead author of the Cochrane review on midwife-led continuity of care.