VBAC and home birth: evaluating the evidence

Thanks to a recent pronouncement from the American College of Obstetricians and Gynecologists, my two-year old daughter, who arrived via a vaginal birth after Cesarean section (VBAC), may not be a medical rarity for much longer. In a previous post, I discussed possible causes for the steep 15-year decline in the percentage of U.S. women who have delivered a child vaginally after a previous Cesarean birth (currently fewer than 1 in 10). In March, at a conference held at the National Institues of Health in Bethesda, Maryland, an expert panel concluded that the scientific evidence did not support ACOG's existing recommendation that surgical and anesthesia personnel be "immediately available" during a trial of labor. However, they found evidence that this restrictive requirement had caused many hospitals without 24-hour availability of these services to discontinue VBAC entirely.

To its credit, last week ACOG released an updated version of the guideline that states that a trial of labor is a reasonable option for the vast majority of women who desire a vaginal delivery after a previous Cesarean, including those who have had more than one prior Cesarean and those carrying twins. While continuing to assert that mothers and babies are best served by access to emergency resources, they add: "Respect for patient autonomy also argues that ... [an institutional no-VBAC policy] cannot be used to force women to have cesarean delivery or to deny care to women in labor who decline to have a repeat cesarean delivery." Amen.

Now I'll to turn to another controversial maternity care topic: home birth. The subject of a widely viewed 2008 documentary and Time Magazine story, out-of-hospital births represented less than 1 percent of all births in the U.S. in 2005, according to government researchers. A recent meta-analysis of previous studies comparing planned home and planned hospital births that concluded that the former was "associated with a tripling of the neonatal mortality rate" elicited a variety of reactions from health professionals in the U.S. and abroad, ranging from ACOG's reiterating its opposition to home births to calls for more research by the American College of Nurse Midwives and the UK's Royal College of Obstetricians and Gynecologists.

I agree that more research is needed. But as for the analysis itself, there are at least two reasons to question whether it should cause many (or any) women to reconsider their home birth plans. First, while "tripling" in neonatal deaths sounds scary, this is a relative rather than an absolute difference in risk. Reading the fine print, neonatal death occurred in 0.15 percent for planned home and 0.04 percent for planned hospital births. That's an absolute risk difference of just 0.11 percent, or about 1 extra death for every 1000 births. This difference is very close to the small increased risk of neonatal death during attempted VBAC versus repeat Cesarean section (0.8 extra deaths for every 1000 births), which ACOG has acknowledged should be a mother's choice.

Second, all but 3 of the 12 studies included in the meta-analysis were conducted prior to the year 2000, in populations with much lower Cesarean rates than in the U.S. Overall, only 9.3% of women in the planned hospital birth groups had Cesarean deliveries - a far cry from the 32% that currently occur in the U.S. So while this study's results are most applicable to countries in other parts of the world that have Cesarean rates of 10% or less, it's not clear if it captured the maternal complications that invariably result from doing 3 times as many surgeries.

The bottom line? The available evidence indicates that planned home birth is no riskier for babies, compared to planned hospital birth, than is attempting VBAC compared to choosing a repeat Cesarean delivery.