by Henci Goer

Commentary on: Pang WY, et al. Outcomes of planned home births in Washington State: 1989-1996. Obstet Gynecol 2002;100:253-9. [Abstract]

Study design and results: review of Washington State birth certificate data from 1989 to 1996 comparing 6052 supposedly planned home births of at 34 weeks gestation with qualified home birth attendants with 10,347 similar hospital births.

• neonatal mortality: 3.3/1000 home vs. 1.7/1000 hospital; relative risk 1.99, 95% confidence interval 1.06-3.73
• 5 min Apgar score < or = 3: 4.1/1000 home vs. 2.0/1000 hospital; relative risk 2.31, 95% confidence interval 1.29-4.16

Problems include but are not limited to the following:

• The study includes unplanned home births: A “planned home birth” describes a birth in which the woman:
  • intends to have her baby at home,
  • meets certain medical criteria,
  • has qualified birth attendants, and
  • has access to appropriate equipment, medical specialists and hospital care when necessary

This is an essential distinction because neonatal morbidity and mortality increase greatly when these criteria are not met. The Washington State birth certificate form, from which the data for the study were collected, provides no means of ascertaining whether the woman intended to birth at home. The way the form is constructed, a woman who gave birth precipitously at home with no attendant and was brought into the hospital by ambulance would be considered a “planned home birth” according to Pang et al.

In addition, the study reports that 8% of home births were attended by physicians, but no known physicians in Washington State provide home birth services. This means that home births listing a doctor as the birth attendant could not have been planned home births.

• The study includes planned home births with unqualified attendants: The investigators accept nurses as qualified home birth attendants, but nurses are not qualified birth attendants in any setting. (Nurse-midwives do attend home births in Washington and were considered and analyzed separately.) Also, the investigators make no attempt to ascertain the education, licensure status, or skill level of the acknowledged home birth attendants. 
  
  
• The study includes preterm births: The study includes births from 34 to 37 weeks gestation. Including preterm births violates the “planned home birth” standard that women must meet defined medical criteria. Having a preterm birth universally excludes women from giving birth at home. The investigators later restrict analysis to babies of at least 37 weeks gestation and weighing at least 2500 g, but the abstract, tables, results, and conclusions are all based on the data set that includes preterm births. 
  
  
• The study doesn't investigate whether the choice to birth at home was at fault in neonatal deaths: The investigators note that 10 of the 20 babies who died had diagnoses of congenital heart disease or respiratory distress. An additional three babies had major congenital anomalies. They do not say whether the deaths occurred at home or in hospital, nor do they speculate about how the choice of birth setting may have affected neonatal outcome in individual cases. The investigators could have reviewed the medical records on these 20 deaths, which would have provided a more accurate picture of whether home birth care affected outcome, but they did not. There is also the possibility that women who knew the baby would have anomalies incompatible with life chose to birth in the privacy and comfort of their homes, and a compassionate birth attendant honored that preference. 
  
  
• The study groups are not truly comparable: The study authors make no effort to ascertain whether women choosing hospital birth and women supposedly planning home birth had similar risk factors. For example, the investigators could have matched women according to such relevant factors as whether this was a first birth or whether the baby had a heart defect or other serious anomaly. In point of fact, a Washington State government study reported that 7 per 1000 women planning home birth with a licensed midwife had a baby with a major malformation versus 2 per 1000 planning hospital birth. The difference may be because some home birthers are less likely to terminate a pregnancy, but it means that the excess of deaths from this cause in the home birth population could simply be because there were more babies at risk.
  
  
• The researchers should have matched women planning birth at home with women using hospitals in the same local area. Lumping together women planning home birth in a rural area with a small community hospital with women planning hospital birth in a tertiary care teaching hospital is comparing apples to oranges. Small hospitals lack the facilities and staff of sophisticated medical centers, and outcomes may be different when there are complications. 
  
  
• The investigators “cherry pick” their outcomes: The researchers fail to report all relevant outcomes while reporting some irrelevant ones. The study reports, among other things, that women planning home birth had higher incidences of postpartum bleeding and prolonged labor. Postpartum bleeding with no qualifying information is meaningless. Did the mother require a transfusion? A hysterectomy? Become severely anemic? If none of the above, then this outcome is not clinically significant. As for prolonged labor, it has little association with poor infant outcomes. It may even be an artifact in that hospital labors may be artificially shortened by use of oxytocin or cut short by cesarean section.

Other relevant items reported on the birth certificate list are first-time cesarean, forceps delivery, vacuum extraction, umbilical cord prolapse, fetal distress, birth injury, meconium aspiration syndrome, and newborn seizures. The investigators say nothing about these.

“Stacking the deck” in this fashion raises questions about whether outcomes in these categories favored home birth. Studies comparing intervention rates in home versus hospital births in low-risk women uniformly find many more cesareans and vaginal instrumental deliveries as well as much greater use of potentially injurious drugs, procedures, and restrictions of all kinds. A study using Washington State data from the same time period reports that 20% of first-time mothers had a cesarean and nearly 25% had a vacuum extraction or forceps delivery. These two procedures alone have high potentials for doing harm. Failure to take the disadvantages of hospital birth into account gives an unbalanced and misleading picture.

Comment: The Pang et al. study alarmingly concludes that planned home birth confers twice the neonatal death rate of planned hospital birth, but, in fact, the absolute difference amounts to 1 in 1000. It would take only a few mischaracterized births to make the difference disappear altogether or swing the advantage to the home birth side.

If these and other flaws in the Pang et al. study are not enough to condemn it, the conclusion that “planned home birth” imposes greater risk is contradicted by a large body of, in many cases, higher quality studies. This includes a much better done study by the Washington State Department of Health that overlaps much of the data used by Pang et al. Prior to the Pang study we had no study of home birth meeting the criteria for “planned home birth” that showed excess risk in the home birth population. We still don't.

Bibliography:

Cawthon L. Planned home births: outcomes among Medicaid women in Washington State. Report 7.93. Olympia, WA: Office of Research and Data Analysis, Washington State Department of Social and Health Services, 1996.

Goer H. Homebirth: Is It Really a Safe Option? Access at: http://www.parentsplace.com/expert/birthguru/ articles/0,10335,243383_533478,00.html articles/0,10335,243383_533478,00.html

Lydon-Rochelle M et al. Association between method of delivery and maternal rehospitalization. JAMA 2000;283:2411-6.

Vedam S. Home birth versus hospital birth: Questioning the quality of the evidence on safety. Birth 2003;30:57-63.