Pregnant woman's chance of C-section in Massachusetts linked to hospital choice

While the standard method of delivery for most pregnant women is through vaginal birth, medical complications related to age and health conditions often compel doctors to perform a cesarean section to better preserve the health of the mother and her infant.

Considered to be the second option for delivery, C-sections are actually performed with wide variation, as multiple surveys have revealed the procedure is utilized more in some hospitals than others.  One explanation for the disparity rates is that some hospitals serve a greater number of women with complications warranting the procedure.  However, new research has revealed  this reasoning may not be the case.

A new study from the Harvard School of Public Health (HSPH), in collaboration with the Massachusetts Department of Public Health, found C-section variation among hospitals in Massachusetts does not change when high-risk factors for the procedure – such as age, hypertension, diabetes – are taken into account.

In other words, the same woman would have a different likelihood of having a C-section depending on the hospital where she was treated.

While C-sections have been nearly perfected over the years and can potentially be life-saving for both mother and infant, the procedure can come with side effects if it is not medically necessary.

“The morbidity associated with a C-section is higher than a vaginal delivery,” said Dr. Manny Alvarez, senior managing health editor for  “And with any surgery, there can be complications.  They include excessive blood loss, infection, bowel obstruction, deep vein thrombosis – and C-sections are generally associated with a much slower recovery period.”

According to the Centers for Disease Control and Prevention, cesarean delivery has increased more than 50 percent over the last decade, currently accounting for 31.8 percent of all births in the United States.  Part of the motivation behind the Harvard study was to better understand what is driving this upward percentage.

“A few things cross your mind (to explain this),” senior author S. V. Subramanian, professor of population health and geography at HSPH, told  “Is it the case that mothers in terms of their risk are getting worse?  Are there more older mothers, more mothers with other complications such as hypertension and diabetes?  People think this is going up in the population, so it’s all being driven on the demand side.”

“Another explanation,” he added, “could be that more women want C-sections, so they’re electing for one.  They want it because it’s safe, and it’s an easy process.”

But the third reason Subramanian speculated on revolved around the hospitals.  Was there something in regards to each individual hospital’s cultural practices that could be contributing to this phenomenon?

Utilizing data from the Pregnancy to Early Life Longitudinal data system, Subramanian and colleagues from HSPH, Boston University, Massachusetts General Hospital and the state department of public health analyzed more 228,864 births in Massachusetts from 49 of the state’s hospitals between 2004 and 2006.  The data accounted for 98 percent of all record births for that time period.

Overall, 27 percent of the women who gave birth to full-term infants in Massachusetts during this period had C-sections.  Among the hospitals in the state, C-section rates varied from 14 percent to 38 percent.

In an attempt to better explain the variation, the researchers re-analyzed the data after controlling for a variety of characteristics and different C-section risk factors.  These included everything from the mother’s age, education, race, ethnicity, birth weight of the infant, whether labor was induced, time of birth, and pre-existing health of the mother (for example: if she had hypertension or diabetes).

Initially thinking this might alter the results, the researchers were very surprised when they adjusted the numbers for a second time.  The results stayed exactly the same, meaning the fact that different hospitals have different risk factor profiles for different mothers doesn’t explain any of the variation.  Instead, the data indicates hospital practices and general hospital culture somehow contribute to the varying percentages.

Subramanian also noted financial incentives and liability concerns could also play a role in the decision to perform more C-sections.  The research also found hospitals with more midwives tended to perform more vaginal births than other hospitals.

Overall, Subramanian said this study should ultimately motivate hospitals to re-examine their practices and criteria for determining when to perform C-sections – especially if there isn’t a medical need to do so.

“(The study) is telling us there is no clear flow chart that is standardized across hospitals which says, ‘This is the standardized protocol under which a C-section should happen.’” Subramanian said.  “If that does exist, it’s not public and the hospitals seem to have their own benchmarks.   Now that we have established that case mix isn’t a driving factor…can we come up with a standard procedure that all hospitals adhere to?”

The study was published in the online issue of the journal PLOS ONE.