After a woman has a cesarean section, she is almost sure to deliver future babies by having her abdomen cut open again.
That's why efforts to reduce the overall C-section rate - now one out of every three deliveries - often focus on preventing initial cesareans.
Initial cesareans make up 60 percent of all C-sections, and the expert consensus is that many are not medically necessary.
Consumer Reports, the venerable product-
testing group, this month rates 1,500 of the nation's hospitals on how well they avoid first-time cesareans in low-risk women - women carrying a single, properly positioned, full-term baby.
Consumer Reports drew on public billing records from 22 states from 2009 to 2012 to evaluate hospitals that had at least 100 low-risk deliveries in a two-year period. It found the national average rate for first-time cesareans in low-risk women was about 18 percent - much higher than the 12.6 percent rate in 2000, used as a benchmark.
"Because a hospital's C-section rate can be hard to find, it's likely that most families are unaware of the huge differences in medical practice," Consumer Reports said.
Consumer Reports' data did not include factors that can increase the risk of a C-section, such as obesity, diabetes or high blood pressure.
Still, some geographic areas had "dramatic," inexplicable variations. In Los Angeles, for example, cesarean rates in low-risk women ranged from a high of 55 percent at one hospital, to a low of 15 percent at another center.
The range in the Philadelphia region, including South Jersey, was narrower. At the low end were Jennersville Regional in West Grove (12 percent) and Cooper Health System in Camden (13 percent). At the high end were Pottstown Memorial Medical Center (23 percent) and Lourdes Medical Center of Burlington County in Willingboro (28 percent). Asked about their Consumer Reports rates, several local hospitals cited care of high-risk patients such as those carrying multiple fetuses - even though the Consumer Reports analysis focused on low-risk women.
"Like our peers at other large, urban hospitals, many of our deliveries follow high-risk pregnancies requiring special care and close monitoring, which may result in higher-than-average rates of cesarean deliveries," e-mailed Penn Medicine, which last year had 8,885 births at the Hospital of the University of Pennsylvania (16 percent rate in Consumer Reports) and Pennsylvania Hospital (22 percent).
Why do so many women with no clear need for a surgical delivery wind up having one?