The authors of a new study in the July 2010 issue of Obstetrics and Gynecology found that in order for a successful analysis of home birth to be conducted in the United States, a distinction needs to be made between planned and unplanned home births. This study, titled Characteristics of Planned and Unplanned Home Births in 19 States, by Eugene Declercq, PhD, Marian F. MacDorman, PhD, Fay Menacker, DrPH, CPNP, and Naomi Stotland, MD has not received any media coverage, while another home birth study scheduled to be published in the American Journal of Obstetrics and Gynecology in September 2010 has generated international attention.
The rate of home births in the United States has not been higher than 0.67% of all births since 1989. One basic problem with analyzing home births is that they occur so infrequently that it is difficult to gather data from a population large enough to make the study of trends and outcomes reliable. While studies have been published, their design and methodology have been criticized. Because home birth is so rare, any studies conducted have “limited power to identify differences in critical outcomes, such as maternal or neonatal deaths.” In addition, studies of home births from countries in which giving birth at home is more common and integrated into the maternity care system may not apply to the United States.
Home birth and other out-of-hospital births were essentially immeasurable in the U.S. prior to 1989, when a checkbox was added to the U.S. Standard Certificate of Live Birth. In 2003, the standard birth certificate was revised to distinguish between planned and unplanned home births. Only 19 states have adopted this revision.
There are two conflicting biases inherent in studies that rely on larger datasets from the National Vital Statistics System. First, distinguishing planned from unplanned home births is a recent addition. Second, the documentation of births that occurred at home did not differentiate between those which resulted in prenatal or intrapartum transfer to a hospital
The authors summarize their methodology as such:
Data are from the 2006 U.S. vital statistics natality file. Information on whether a home birth was planned or unplanned was available from 19 states, representing 49% of all home births nationally. Data were examined by maternal age, race or ethnicity, education, marital status, live birth order, birthplace of mother, gestational age, prenatal care, smoking status, state, population of county of residence, and birth attendant. We could not identify planned home births that resulted in a transfer to the hospital.
Table 1 (above) compares the characteristics of planned and unplanned home births to those that occur in hospitals. Data were from the National Center for Health Statistics’ de-identified vital statistics natality files from 2006. Information on planned versus unplanned home birth was only available from California, Delaware, Florida, Idaho, Kansas, Kentucky, Nebraska, New Hampshire, New York [excluding New York City], North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Vermont, Washington, and Wyoming because these 19 states had adopted the 2003 revision of the U.S. Standard Certificate of Live Birth by January 1, 2006.
As shown, 9,810 (83.2%) of the 11,787 home births studied here were identified as planned home births.
Racial disparities were uncovered:
- Mothers with planned home births were overwhelmingly non-Hispanic white (90%).
- 49.7% of mothers having hospital births and 45% of unplanned home births (45%) were non-Hispanic white.
- Hispanic mothers accounted for almost 1/3 of hospital births and 1/4 of unplanned home births
- Only 5.6% of planned home births were to Hispanic mothers.
- Non-Hispanic black women accounted for 24% of unplanned home births, which is double their percentage for hospital births and 10 times their percentage for planned home births.
- 69% of home births among non-Hispanic black mothers were unplanned.
Mothers having planned home births were also more likely than mothers having unplanned home births or hospital births to be:
- older than 30
- born in the United States
- to have at least some college education
- to have a gestation of 37 or more weeks
Unplanned home birth and other risk factors:
- 26% of all mothers with an unplanned home birth had no reported prenatal care (49% among Hispanic mothers in particular)
- 19.7% of unplanned home births involved a mother who smoked
- 54% of unplanned home births was to mothers who were unmarried
Parity and home birth:
- 53% of planned and 48% of unplanned home births were to mothers with parity of three or more versus 28% for hospital births.
Figure 1 (above) shows planning status from the perspective of care providers.
- Nearly all home births attended by CNMs or “other midwives” were planned home births.
- 65% of birth with “other” attendants were planned
- Authors also examined (data not shown here) the race/ethnicity of the mothers and birth attendants in planned home births and discovered that “other midwife” was the most common category across all race/ethnicity subgroups, but:
- Non-Hispanic black mothers were the most likely to have an MD attending the planned home birth at 14%.
- White and Hispanic mothers only had an MD at their planned home births 2% of the time.
Figure 2 (above) shows the gestational age for planned and unplanned home births.
- Premature births accounted for 26% of unplanned home births versus 3% of planned home births.
- Planned home births show a gestational age distribution concentrated at 39 or more weeks
- 80% of planned home births at 39 or more weeks versus 42% of the unplanned home births.
- 58% of hospital births occur at 39 or more weeks (the authors did not show this data).
Table 2 (above) shows planning status by state. Noteworthy is the relationship between the overall proportion of (all) home births in a state and the proportion of planned home births.
- In states with at least 1% of their births at home, 95% of their births on average were planned.
- In states with less than 0.5% of their births at home, 73% on average were planned.
The authors contrast home birth rhetoric in the United States with the manner in which it is framed in non-U.S. countries in which home birth is both accepted and encouraged.
The debate over home birth has generated an unusual amount of commentary in recent years. In England steps have been taken to encourage the option of a planned home birth, but the American College of Obstetricians and Gynecologists issued a position statement in 2007 that contends that birth should only take place in the hospital setting, and a resolution passed at the 2008 American Medical Association meeting criticized home birth. At the same time, a popular 2008 U.S. movie documentary advocated home birth, as have some consumer-oriented books. Despite the controversy, there has been relatively little change in overall home birth rates over the past two decades. There was a slight increase between 2004 and 2005, followed by a leveling-off in 2006, resulting in an overall home birth rate (0.59%) that was no higher than the rate in 1997.
The debate over home birth appears to have less to do with the frequency of its occurrence than what it symbolizes for the groups on either side of the issue. For home birth advocates, it represents a rejection of what they see as the overmedicalization of a natural process and the opportunity for mothers and families to control their own birth experience. The increased activism concerning home birth also comes at a time of record cesarean rates in the United States and may be, in part, a reaction to that. For medical societies in the United States, home birth is described in their resolutions as a practice that, because labor is unpredictable, involves unnecessary risks to the health of mothers and newborns.
It seems unlikely that such a polarized debate can be resolved by scientific studies, especially because a randomized trial of place of birth is probably not feasible.
A primary limitation of the study that the authors repeatedly note is that they could only report on home births that took place at home and not hospital transfers. Since the birth certificate variable regarding planned or unplanned status is new, not much is known about its quality. Additionally, the results cannot be generalized to the rest of the United States.
The authors discuss how a prospective cohort analysis, such as one that is underway in England, could track mothers from late pregnancy to the immediate postpartum and note their intention concerning their place of birth. What they call an “intention-to-treat” analysis could provide information on planned home births that occur at home versus planned home births in which women transfer to a hospital. The 2009 home birth studies from the Netherlands (de Jonge) and British Columbia (Janssen) conducted such analyses retrospectively and, after controlling for characteristics of women in the studies, found similar outcomes between home and hospital births.
One risk factor identified by this study is one that the authors state has received little attention is unplanned home births. While the number is small, these births should generally occur in a hospital setting based on the screening criteria used for planned home births. One potential problem in identifying this population in advance is that many receive no prenatal care. They conclude that “any comparative analysis of outcomes with low-risk hospital births would exclude those home births that were potentially at the greatest risk for a poor outcome.”