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Cesarean delivery may increase the risks of maternal and neonatal morbidity and mortality (BMJ 2007 Nov 17;335(7628):1025, Lancet 2010 Feb 6;375(9713):490). Nevertheless, rates of cesarean deliveries have been on the rise over the past 2 decades in the United States and world-wide, due in large part to an increase in planned, elective cesareans. Midwife care has previously been associated with reduced rates of episiotomy and instrumental vaginal delivery, reduced use of analgesia during labor, and increased maternal satisfaction. The COSMOS trial in Australia recently investigated the effect of primary midwife care on cesarean rates in women with low obstetric risk in early pregnancy.
A total of 2,324 women with singleton pregnancy < 24 weeks gestational age were randomized to one-to-one primary midwife care vs. usual care through the postpartum period. In the primary midwife care group, the majority of care for each woman was provided by a single midwife to insure continuity (with care by back-up midwives as necessary due to scheduling conflicts). Any complications were managed by collaboration between the primary midwife and an obstetrician or other care provider. In the usual care group, women had the option of midwife team care (without one-to-one relationship between midwife and patient), care by an obstetric trainee, or combined care by community-based general practitioner and hospital staff, with care provided by on-duty midwives and doctors for labor, birth, and postnatal care. Most women in the usual care group (78%) received midwife team care. All women in each group saw an obstetrician at booking, at 36 weeks gestation, and at postdates if required. Women were excluded from the trial for conditions putting them at high obstetric risk, including previous cesarean section, history of obstetric complications, cardiac disease, diabetes, and obesity. The trial was conducted at a single hospital in Melbourne, Australia.
The overall rate of cesarean deliveries was significantly lower with primary midwife care (19.4%) than with usual care (24.9%) (p = 0.001, NNT 19) (level 1 [likely reliable] evidence). Cesarean rates were also lower in a subgroup analysis of 1,595 primiparous women (24.9% vs. 32.4%, p < 0.001, NNT 14). There were no significant differences in the rate of planned cesarean sections (3.1% vs. 3.5%) or in overall cesarean sections in a subgroup of multiparous women (6.2% vs. 8%).
Primary midwife care was also associated with significantly higher rates of spontaneous vaginal birth (63% vs. 55.7%, p < 0.001, NNT 14), and with lower rates of epidural analgesia use (30.5% vs. 34.6%, p = 0.04, NNT 25) and episiotomy (23.1% vs. 29.4%, p = 0.003, NNT 16). Infant admissions to special or neonatal intensive care were also lower with primary midwife care (4% vs. 6.4% of live births, p = 0.01, NNT 42) (BJOG 2012 Nov;119(12):1483).
A number of issues may limit the generalizability of these findings. From these data, it cannot be determined whether midwife care specifically or, more generally, continuous care from a single provider is the factor responsible for the results. Furthermore, cesarean rates differ around the world and may even differ among institutions in the same area. The authors note that the baseline cesarean rate at the study hospital was relatively high. The effects of midwife care are likely to depend on a number of demographic and cultural variables.
For more information, see the Overview of labor and delivery topic in DynaMed.