It is important for the public and health workforce to reflect carefully on the results of a study on midwifery care released this week, according to a Professor of Obstetrics and Gynaecology from the University of Auckland.
Last week, research published by Wernham et al from the University of Otago compared birth outcomes in women who started their pregnancy care with self-employed midwives - compared with those who booked with a medical provider (predominantly private obstetriicians).
These authors reported that women who booked with a self-employed midwife had an increased risk of their babies being born in poor condition with asphyxia or neonatal encephalopathy.
“It cannot be concluded from this retrospective study that the increased adverse outcomes in women who booked with a self-employed midwife are definitely due to the model of care,” says Professor Lesley McCowan, the head of Obstetrics and Gynaecology at the University of Auckland.
“As was highlighted by the authors of this new report, the rates of many pregnancy risk factors (social deprivation, obesity, smoking) were higher among the women who booked with self-employed midwives compared to those who booked with private obstetricians,” she says.
“The authors have done their best to control for differences between the two groups using statistical methods, but it is inevitable that differences will remain between such disparate groups,” says Professor McCowan.
Professor McCowan says the findings from this paper were a surprise to New Zealand practitioners as they are out of keeping with the findings from randomised controlled trials conducted in other countries.
“They are also out of keeping with recent New Zealand Perinatal Mortality data which shows an encouraging reduction in stillbirths after 28 weeks and in particular a reduction in deaths of babies who died in labour,” she says.
“Reduction in baby deaths in labour in New Zealand is at least in part attributable to high quality midwifery care,” says Professor McCowan. In New Zealand the rate of stillbirth after 28 weeks is lower than that in Australia, where pregnancy care is generally led by specialists.”
“The paper by Wernham et al raises important points that require further research and clarification,” she says. “It is important to emphasise that New Zealand has a safe model of maternity care but improvements are always possible.”
“Other commentators have highlighted that there are a number of limitations with retrospective research,” says Professor McCowan. “An important one for this study is that about 30 percent of women who book for pregnancy care with a self-employed midwife will receive a consultation with an obstetrician at some stage in their pregnancy, because they develop risk factors or pregnancy complications.”
“This will often result in a medical led model of care in late pregnancy and during birth,” she says. “These data about specialist consultation are are not available in this paper, so it is possible that a number of women who experienced asphyxial complications in this report would have been receiving medical supervised care at the time of birth.”
“There is a third common model of care that is not included in the paper, where women book for care with a District Health Board team and receive input from both midwives and specialists. Data from this group would make an interesting comparison,” says Professor Cindy Farquhar, post graduate Professor of Obstetrics and Gynaecology at the University of Auckland.
“It is also important to highlight that severe asphyxia and in particular neonatal encephalopathy are rare events, with neonatal encephalopathy affecting 1-2 babies in every 1000 births,” she says. “The 40 percent increase in risk reported in this paper needs to be interpreted in that context.”
“Information about mode of birth and admission of babies to neonatal units is not available in the paper and this information would assist with a fuller understanding of differences and possible trade-offs between the two models of care,” says Professor Farquhar.
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