11/21/2011 03:39 pm ET | Updated Jan 21, 2012

C-sections and Pre-term Births on the Decline -- Is There a Link?

Two really exciting statistics were announced this week: The c-section rate in the U.S. actually declined in 2010 from the previous year (from 32.9 percent to 32.8 percent) for the first time in a decade, and the preterm birth rate dropped for the fourth straight year to 12 percent.

I suspect these two trends are related -- and for all of the right reasons. The c-section rate in the U.S. shot up over the past four decades from 5 percent in 1970 to its current rate for lots of reasons -- more fetal monitoring, more lawsuits, fewer vaginal deliveries after a prior c-section and convenience.

The "convenience" c-section became popular because it's more convenient for the obstetrician and for the patient to know that the delivery will take place next Wednesday at 8 a.m. then to wait for labor to begin spontaneously, and then wait the 6-36 hours for labor to lead to delivery. Labor is unpredictable, it happens at night and on weekends, and it takes a long time. Scheduled cesareans, in contrast, are quick and only take a one-hour slot in Outlook.

What started to happen, however, was that c-sections were getting scheduled earlier and earlier in the pregnancy, and given uncertainty in the actual due-date for some pregnancies, the occasional scheduled c-section was being done before 37 weeks of gestation, producing a preterm newborn.

Simultaneously, a large body of literature was showing that the late-preterm period between 34 and 36 weeks mattered, and even the 37th and 38th week led to complications that could often be prevented by waiting until the 39 weeks for delivery (if nature didn't take its course first). The risk of breathing problems and even death went down week by week all the way until 39 weeks of gestation.

When public health officials, activist obstetricians and hospital administrators saw these data, they started enforcing rules against "optional" deliveries before 39 weeks. One of my favorite studies from the Intermountain Health Service shows how a team of clinicians and administrators at a group of hospitals in Utah put together a policy, enforced it and saw their complication rate drop dramatically.

Of course waiting for 39 weeks allowed more women to go into labor naturally and never end up in the operating room in the first place.

These policies, many of which were implemented 3-10 years ago, are having an additive effect now as women who didn't have a c-section with their first baby now are not having a repeat c-section with their second baby.

And the policy of waiting for elective deliveries until 39 weeks has kept more babies from being born before 37 weeks. (It's also possible that the increased use of progesterone to prevent repeat preterm deliveries is impacting this statistic as well, although that's a topic for another time.)

So kudos and congratulations to the champions of women's health who are seeing the results of their work in national statistics: obstetricians everywhere, the March of Dimes -- which has tirelessly advocated for measures to reduce prematurity, public health officials and our patients who are making the best choices for themselves and their babies.

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