Study of Native American Community with Low Cesarean Delivery Rate Identifies Practices that May Help Lower U.S. Cesarean Rate

Contact:
Angela Sharma
Annals of Family Medicine
(913) 269-2269
asharma@aafp.org

LEAWOOD, Kan. - The high incidence of cesarean delivery across the U.S. population may be preventable, according to a new study published in the May/June 2003 issue of Annals of Family Medicine.

"Family physicians may be able to reduce the cesarean delivery rates in their obstetrical units by adopting practices characteristic of communities with c-section rates much below the national average," said the study's lead author, Lawrence Leeman, M.D., M.P.H., from the University of New Mexico.  "By avoiding unneeded inductions, not routinely intervening with cesarean delivery for labor dystocia until at least four hours of adequate contractions, ensuring adequate provision of continuous labor support and facilitating consultation prior to nonemergent cesarean delivery, doctors may be able significantly reduce the cesarean delivery rate."

There has been a marked increase in the rate of U.S. cesarean delivery over the past three decades.  According to background information provided in the study, the U.S. cesarean rate rose from 4.5 percent in 1970 to 24.4 percent in 2001. Researchers point out the increased rate has not significantly reduced the rate of neonatal morbidity and mortality.

Leeman and his colleague conducted an epidemiological study of a predominantly Native American community of northwestern New Mexico known to have a low cesarean delivery rate (7.3 percent), despite a high incidence of obstetrical risk factors.  The researchers studied all pregnancies from 1992 to 1996 in the communities served by the Zuni-Ramah Indian Health Service Hospital in an attempt to identify factors associated with the low cesarean delivery rate.

The authors found, "The cesarean delivery rate for the Zuni-Ramah population was significantly lower than the national rate in 1996 (7.3 percent vs. 20.7 percent) for total cesarean deliveries.  Trial of labor after cesarean was attempted in 93 percent of pregnancies in the study population … compared to 42 percent of women nationwide in 1994. The cesarean delivery rates for women with diabetes in pregnancy (11.5 percent vs. 35.4 percent) and preeclampsia (14.8 percent vs. 37.4 percent) were significantly lower than nationwide rates."

When the researchers studied the indications for cesarean delivery (including dystocia, breech, fetal distress, elective repeat and other) to determine the relative influence of each on the low cesarean rates, they found that for each of the indications, the cesarean rate was significantly lower for Zuni-Ramah than the U.S. population nationwide. Specifically, they found, "The lowest relative risk of a primary cesarean delivery was for labor dystocia (0.22), which is the indication for over 50 percent of all U.S. cesareans." Moreover, they point out, "Only 0.5 percent of Zuni-Ramah births are elective repeat cesarean deliveries compared to 4.66 percent nationally."

Importantly, the authors point out that an earlier study of the same population revealed no adverse outcomes due to deferred cesarean sections.  "Perinatal mortality and neonatal resuscitation rates were similar to nationwide rates," notes Leeman.

In their analysis, the researchers suggest the low cesarean rate likely results from a complex interaction between the perinatal system, cultural attitudes toward childbirth and genetics.

Specifically, they write, "The low cesarean rate may be influenced by the predominant involvement of family physicians and nurse-midwives … who have a significantly lower rate of cesarean deliveries and other obstetrical interventions compared to obstetrician/gynecologists." 

Additionally, the researchers attribute the low cesarean rate "to a decreased use of cesarean delivery for labor dystocia and almost universal acceptance of trial of labor after cesarean."

The authors explain that birth weight also may play a role in the lower incidence of cesarean delivery as, "The average weight of live births…in the Zuni-Ramah population was 118 grams below the U.S. average birth weight."

Lastly, the researchers suggest that the pronatalist cultural attitudes toward childbirth and the increased social support within the Zuni-Ramah community may influence the low rate. "The ability to birth with minimum obstetric intervention appears to be a cultural norm based on the reluctance of women to utilize obstetrical interventions."

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Annals of Family Medicine is a peer-reviewed research journal that provides a cross-disciplinary forum for new, evidence-based information affecting the primary care discipline.  Launched in May 2003, the journal is sponsored by six family medical organizations, including the American Academy of Family Physicians (AAFP), the American Board of Family Practice (ABFP), the Society of Teachers of Family Medicine (STFM), the Association of Departments of Family Medicine (ADFM), the Association of Family Practice Residency Directors (AFPRD) and the North American Primary Care Research Group (NAPCRG).  The journal is published six times per year and contains original research from the clinical, biomedical, social and health services areas, as well as contributions on methodology and theory, selected reviews, essays and editorials.  A board of directors with representatives from each of the sponsoring organizations oversees the Annals. Complete editorial content and interactive discussion groups can be accessed free of charge on the journal's Web site, www.annfammed.org.