Regular contributor Henci Goer, author of several books including Optimal Care in Childbirth as well as the expert on Lamaze International's 'Ask Henci' site, takes a look at a recent study that examines the wide divergence in cesarean rates amongst U.S. hospitals. Read Henci's take and see what she concludes might be behind this rate variability. - Sharon Muza, Community Manager, Science & Sensibility

© Patti Ramos Photography

If any doubt remained that the likelihood of cesarean depends mostly on care provider philosophy and practices, a study of variation in cesarean rates in U.S. hospitals has laid it to rest. Investigators plotted cesarean surgery rates during 2009 by their percentile at 593 U.S. hospitals with at least 100 deliveries, comprising 817,318 women in all (Kozhimanni 2013). Rates ranged from 7% to 70%, a 10-fold variation.

Thinking that hospital factors might explain some of the variation, the investigators compared rates according to hospital size, whether the hospital was a teaching hospital, and whether it was rural. None had any effect. Average cesarean rates were similar to the overall average rate regardless of hospital characteristics.

Variation in population characteristics likewise could explain variation in cesarean rates. Accordingly, investigators looked at a more homogeneous low-risk subset of women who were at term (37 weeks or more), carrying one head-down baby, and who had no prior cesareans. This, they reasoned, should reduce the variation in rates. Wrong again. The range widened. Rates among low-risk women ranged from a little over 2% to nearly 37%, a 15-fold variation instead of a 10-fold one.

The investigators stopped with expressing concern over the large variation in cesarean rates, writing: 'There is an urgent need to address maternity care quality in general and rising cesarean rates and variation in practice patterns in particular' (p. 531), but their data tell us something more: few hospitals had anything close to reasonable rates.

The mean cesarean rate among women overall was 33%. The World Health Organization holds that cesarean rates should not exceed 15% because research shows that as cesarean rates rise above this threshold, they necessarily are performed in less clear cut situations, and the risks of the surgery begin to outweigh its benefits. Beyond 15%, maternal and neonatal morbidity and mortality rise in parallel with further increase. Only 2 of the 593 hospitals had cesarean rates of 15% or less. Indeed, only 21 hospitals had rates of 20% or less.

In the low-risk population, the mean cesarean rate was 12%. The recent analysis of 18,084 women planning birth center births gives us a fix on whether this is a reasonable rate for low-risk women (Stapleton 2013). Of the 14,881 women admitted in labor to the 79 participating birth centers, 6% delivered by cesarean, and perinatal outcomes were equivalent to those in similar women planning hospital birth. Only 23 of the 593 hospitals had a cesarean rate of 6% or less in their low-risk cohort.

To be fair, the low-risk hospital dataset wasn't able to identify women with problems that would increase their likelihood of cesarean but who would have been excluded from birth center care. The birth center data, however, provides a handle on the possible effect on cesarean rate. Six percent of women planning birth at the birth center were risked out because of pre-eclampsia, non-reassuring fetal testing, postdates, or prelabor rupture of membranes and no labor. Let us assume that these problems occurred at the same rate in the low-risk hospital population. Let us further assume that all women with these problems ended up with a cesarean, which is highly unlikely. Those assumptions would boost the birth center baseline cesarean rate of 6% by another 6% or to 12% for the low-risk hospital population. Even making this extreme assumption, 271 hospitals, nearly half, had rates greater than 12%.

What's the take-home? Practitioners with appropriate cesarean rates are thin on the ground. Women need to seek out care providers whose judgment on when a cesarean is indicated can be trusted. (I should add that they are likely to have better luck with a midwife, but it isn't a sure thing.) Women free of medical or obstetrical risk factors may wish to plan to birth in a free-standing birth center or at home because while individual practitioners' rates may vary within institutions, a high hospital rate-true of nearly all of them-creates a cesarean-friendly culture.

How would you use this research study when teaching classes or working with clients or patients? Do you think that women do enough research and investigation when selecting a provider and a birth facility? Please share your thoughts. - SM

References

Kozhimannil, K. B., Law, M. R., & Virnig, B. A. (2013). Cesarean Delivery Rates Vary Tenfold Among US Hospitals; Reducing Variation May Address Quality And Cost Issues. Health Aff (Millwood), 32(3), 527-535. doi: 10.1377/hlthaff.2012.1030 http://www.ncbi.nlm.nih.gov/pubmed/23459732

Stapleton, S. R., Osborne, C., & Illuzzi, J. (2013). Outcomes of care in birth centers: demonstration of a durable model. J Midwifery Womens Health, 58(1), 3-14. doi: 10.1111/jmwh.12003 http://www.ncbi.nlm.nih.gov/pubmed/23363029

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