Midwives provide safe primary care for pregnant women who are at various levels of medical risk in British Columbia, Canada, new data suggest.
In most cases, for midwifery clients, birth outcomes were similar to or were better than birth outcomes of patients who had physician-led or obstetrician-led care.
In addition, midwifery clients were less likely to experience preterm births or have low-birth-weight babies and to experience cesarean deliveries or births involving instruments.
“Based on previous research, we know that midwives provide safe care for healthy childbearing people or those with no or few risk factors that might complicate the pregnancy or birth,” lead author Kathrin Stoll, PhD, a research associate in the University of British Columbia’s department of family practice, told this news organization.
“What we didn’t know until now is whether midwives provide safe care to people with moderate and high medical risks and what proportion of B.C. [British Columbia] midwifery clients are low, moderate, and high risk,” she said. “This is important to know because of the misperception that midwives only look after low-risk people. This misperception is sometimes used against midwives to justify giving them fewer resources and supports.”
The study was published in the Canadian Medical Association Journal.
Increasing demand
Registered midwives have been part of the health care system in British Columbia since 1998, according to the study authors. The number of pregnant people who are attended by midwives during birth has steadily increased from 4.8% in 2004-2005 to 15.6% in 2019-2020.
The investigators analyzed 2008-2018 data from the British Columbia Perinatal Data Registry, which contains data for 99% of births, including home births. Their analysis included 425,056 births for which a family physician, an obstetrician, or a midwife was listed as the most responsible provider (MRP). The investigators assessed pregnancy risk status (low, moderate, or high), which was determined on the basis of an adapted perinatal risk scoring system used by the Alberta Perinatal Health Program. They estimated the differences in neonatal and maternal outcomes between MRP groups by calculating adjusted absolute and relative risks.
Among the 425,056 births, 63,151 (14.9%) had a midwife as the MRP, 189,679 (44.6%) had a family physician, and 172,226 (40.5%) had an obstetrician. The antenatal risk score ranged from 0 to 23 (median score, 2).
The proportion of births with midwife-led care increased from 9.2% to 19.8% from 2008-2018. In 2018, midwives were listed as the MRP for 24.3% of low-risk, 14.3% of moderate-risk, and 7.9% of high-risk births in the province. This represented an absolute increase of 9.1% for low-risk, 7.7% for moderate-risk, and 5.7% for high-risk births during the study period.
Among the 12,169 at-home births that took place during the study period, 9,776 (80.3%) were low-risk, 2,329 (19.1%) were moderate-risk, and 64 (0.5%) were high-risk births. As the risk score increased, so did the proportion of midwifery and family physician clients who were delivered by obstetricians. Across all risk strata, more family physician clients than midwifery clients underwent deliveries by obstetricians.
Overall, the risk of perinatal death for midwifery clients was similar to the risk for those under the care of family physicians across all risk levels. Low- and moderate-risk clients with midwife-led care were significantly less likely to experience a perinatal death, compared with those with obstetrician-led care, although the adjusted absolute risk differences were small. In the high-risk group, there was no significant difference in the rate of perinatal deaths between midwife-led and physician-led care.
In addition, clients with midwife-led care were significantly less likely to experience preterm birth and have a low-birth-weight baby regardless of medical risk level. The adjusted relative risk of an Apgar score of less than 7 at 5 minutes was significantly lower for midwife-led care than for physician-led care for nearly all comparisons.
The cesarean delivery rate among midwifery clients in the low-risk group was 7.2%, compared with 12.2% for family physicians and 42.3% for obstetrician clients. Cesarean delivery rates increased for midwifery clients as medical risk increased but were significantly lower than the physician rates across all medical risk levels.
Among low-risk clients, the absolute risk reduction for cesarean delivery was 34.4% with midwife-led care, compared with obstetrician-led care. The absolute risk difference increased to 55.3% for moderate-risk clients and to 42.2% for high-risk clients.