Clinical Review

Does home birth empower women, or imperil them and their babies?

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References

A challenge inherent in many of these studies is identifying exactly what the comparison group is. In addition, some of the data are obtained from discharge summary records, which don’t always reflect the level of risk or acuity.

Oft-cited study has weaknesses

The study that many advocates of home birth cite was conducted in the United States and Canada and published in 2005.17 It evaluated “all 5,418 women expecting to deliver in 2000 supported by midwives with a common certification [certified professional midwives] and who planned to deliver at home when labour began.” The hospital transfer rate was 12.1%, in line with other studies. The risk of adverse outcomes was lower in the group that planned to have home delivery, compared with a “relatively low-risk hospital group.”

The study focused on:

  • electronic fetal monitoring, used in 9.6% of deliveries in the home-birth group, versus 84.3% of the hospital group
  • episiotomy, performed in 2.1% of home deliveries, compared with 33% of hospital births
  • cesarean delivery, 3.7% of planned home deliveries, versus 19% of hospital births
  • vacuum-assisted vaginal delivery, performed in 0.6% of planned home deliveries, versus 5.5% of hospital births
  • neonatal death, at a rate of 2.0 deaths for every 1,000 intended home births. No comparison figure was cited.

One of the weaknesses of this study, as of others, was identification of a comparison group as a “low-risk” population without data to back up that designation. In addition, this study derived its data from birth certificates for 3,360,868 singleton, vertex births at 37 weeks or more of gestation. Data from birth certificates are limited as a basis for accurate risk assessment. Moreover, although the authors of this study asserted that they had no conflict of interest, the investigation was funded by The Foundation for the Advancement of Midwifery.

Study cited by advocates of hospital birth is also flawed

One of the studies many hospital and birthing center advocates cite was published in 2002.18 It involved an analysis of birth registry information on uncomplicated singleton pregnancies at 34 weeks or more of gestation in Washington state between 1989 and 1996. These pregnancies were either:

  • delivered at home by a health professional (n=5,854)
  • transferred to medical facilities after attempted home delivery (n=279)
  • planned to be delivered in the hospital (n=10,593).

Infants whose mothers planned to deliver at home had a higher risk of neonatal death (RR, 1.99; 95% CI, 1.06–3.73) and a higher risk of having a 5-minute Apgar score of less than 3 (RR, 2.31; 95% CI, 1.29–4.16). After adjustment for a gestational-age cutoff of 37 weeks, these risks remained similar.

Nulliparous women, in particular, had a higher risk for prolonged labor (RR, 1.73; 95% CI, 1.28–2.34) and postpartum bleeding (RR, 2.76; 95% CI, 1.74–4.36).

The authors themselves point out a potential flaw in this study: the use of data from birth certificates. These data create “the potential for misclassifying unplanned home births as planned home births.” The difference in outcomes could be significant. For example, the neonatal death rate for unplanned home deliveries in North Carolina and Kentucky was 18 to 20 times higher than the rate for planned home births in these states.19,20

A study from Missouri observes that neonatal mortality was elevated for both planned and unplanned home birth, compared with physician-attended hospital birth.21

Selection bias is a concern

Selection bias is an inherent difficulty in many of these studies. Except for one previously mentioned paper—a very small study—none of the investigations involve randomization. As a result, we cannot exclude the possibility that “women who choose to deliver at home or in a birth center are likely to be different in terms of expectations and approach from women choosing to deliver in hospitals.”22

Risk level can escalate rapidly

What is potentially troubling about home birth is the fact that a low-risk pregnancy that was complication-free during antepartum care can become a high-risk pregnancy in a matter of minutes, necessitating urgent, appropriate obstetric care. Some classic examples of urgent events include cord prolapse, postpartum hemorrhage, bleeding from vasa previa, and shoulder dystocia.

Let’s focus on shoulder dystocia, which occurs in 1.4% of all vaginal deliveries. The authors of one study point out that “most of the traditional risk factors for shoulder dystocia have no predictive value, shoulder dystocia itself is an unpredictable event, and infants at risk for permanent injury are virtually impossible to predict.”23 This may make delivery in the home a high-risk endeavor because of the inability to mobilize an obstetric team to assist with shoulder dystocia maneuvers or perform a Zavanelli delivery.

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