Midwife-Led Care Linked to Positive Outcomes Across Medical Risk Levels

Carolyn Crist

March 08, 2023

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.

Dr Kathrin Stoll

"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 Medscape Medical News.

"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 BC [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 February 27 in the Canadian Medical Association Journal.

Increasing Demand

Registered midwives have been part of the healthcare 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, 9776 (80.3%) were low-risk, 2329 (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 <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.

Labor Induction Varied

Although low-risk midwifery clients were significantly less likely to experience labor induction with oxytocin, high-risk midwifery clients were more than twice as likely to undergo induction with oxytocin than obstetrician clients (adjusted absolute difference, 11.3%).

For most risk levels, midwifery clients were less likely to have an assisted vaginal birth than physician clients, and they were significantly more likely to have a spontaneous vaginal birth. Low-risk clients who had a midwife as the MRP were nearly twice as likely to have a spontaneous vaginal birth than obstetricians' clients, and moderate-risk clients were nearly four times as likely to have a spontaneous vaginal birth.

The rates of vaginal birth after cesarean delivery (VBAC) were significantly higher when a midwife was the MRP. In comparing midwifery clients with family physician clients, the relative and absolute differences were small, but they were larger when comparing midwifery clients with obstetrician clients. Among low-risk clients, the VBAC rate was 85.3% among midwifery clients, compared with 78.6% among family physician clients and 51.5% among obstetrician clients.

In general, the prevalence rates of adverse maternal outcomes (including blood transfusion, intensive care admissions, uterine rupture, and postpartum wound infection) were low for midwifery clients across all risk levels.

Breast- or chest-feeding at birth was significantly more common among midwifery clients across all risk levels as well.

Today, nearly 1 in 4 childbearing people in British Columbia receive care from a midwife at some point during pregnancy, birth, or the postpartum period, the study authors write. During the past 20 years, the profile of clients has evolved to include more moderate- and high-risk patients.

"Clients with more complex medical needs take more time and need more support," said Stoll. "This means that midwives continue to stay on call, responding to pages and urgent medical concerns for their clients with no pay for being on call, no days off even for sick days, and unsafe working hours, often working more than 24 hours at a time. If we want to expand midwifery to communities where they are needed most, we need to provide an enabling environment."

Additional studies are needed as to how different practice and remuneration models affect clinical outcomes, healthcare costs, and client and provider experiences, the study authors write. At the same time, there are several barriers to obtaining funding, conducting studies, and publishing research by and about midwives in Canada, Stoll said ― barriers that she and her co-authors faced.

Seeking Broader Access

Commenting on the study for Medscape, Alixandra Bacon, a registered midwife and president of the Canadian Association of Midwives, said, "These findings demonstrate that pregnant people at any level of medical risk can benefit from midwifery care. This is a testament both to the benefits of the Canadian midwifery model of care and to the seamless integration of midwifery into collaborative teams and the health system." Bacon wasn't involved with this study.

Alixandra Bacon

"If we can realize our goal of equitable access to midwifery care for all families in Canada, we can help to decrease rates of unnecessary medical intervention, preterm labor, and stillbirth," she added.

Jasmin Tecson

"Midwifery is well established across most of Canada. This is yet one more piece of evidence that shows the clinical benefits of midwifery care," Jasmin Tecson, a registered midwife and president of the Association of Ontario Midwives, told Medscape.

Tecson, who wasn't involved with this study, noted the increasing number of clients with more complex health and social needs in Ontario. "It is time to think about how the skills and knowledge of midwives can be used with clients of different risk profiles and how the current scope of practice of midwives can be optimized and expanded," she said. "For example, Ontario midwives are still required to prescribe medications from a limited list, despite the potential additional clinical risks and health system costs that this creates."

The study received financial support from the University of British Columbia Stollery Fund and the University of British Columbia Work Learn Program. Stoll has an unpaid role with the Midwives Association Contract Negotiation Advisory Council. Bacon and Tecson disclosed no relevant financial relationships.

CMAJ. Published February 27, 2023. Full text

Carolyn Crist is a health and medical journalist who reports on the latest studies for Medscape, MDedge, and WebMD.

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