Cervix Size Affects Cesarean Birth Odds

By Meghan Yost, Ivanhoe Health Correspondent

ORLANDO, Fla. (Ivanhoe Newswire) -- Cesarean deliveries in the United States are increasing at an alarming rate. According to the National Center for Health Statistics, they’ve doubled within the last decade. Now, a new study says the size of a woman’s cervix halfway through her pregnancy may play a role in whether she has a cesarean birth.

Researchers at Cambridge University in the United Kingdom and King’s College Hospital Medical School in London looked at the cervical length of 27,472 women at mid-pregnancy -- about 23 weeks after becoming pregnant. It was the first pregnancy for all the women.

The researchers found the larger a woman’s cervix is at mid pregnancy, the higher her chance of delivering her baby by cesarean section. The women with the smallest cervixes at mid-pregnancy -- 16 to 30 millimeters -- had a 16 percent chance of cesarean delivery, while the women with the largest cervix size -- 40 to 67 millimeters – had a 25.7 percent chance of a cesarean birth.

“What concerns me is why we are doing more cesarean sections on young first-time moms,” Robert O. Atlas, M.D., Chair for the department of obstetrics and gynecology at Mercy Medical Center in Balitmore, Md., told Ivanhoe.
According to Dr. Atlas, the caesarean section rate in the United States for first-time mothers is between 18 and 20 percent. “We would like it to be about 15 percent. That was the 2010 goal that was set, but it appears that we’re not going to meet that goal.”

There are multiple reasons the cesarean birth rate is rising, Dr. Atlas explains. “One of the main reasons is doctors are not encouraging vaginal births. Many obstetricians no longer even offer their patients a vaginal birth after they’ve had a C-section,” Dr. Atlas says. Doctors are hesitant because women who have had a prior cesarean section who attempt a vaginal birth are at risk of their uterus rupturing, which is very dangerous for both the mother and baby, Dr. Atlas says.

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SOURCE: Ivanhoe interview with Robert O. Atlas, M.D., The New England Journal of Medicine, 2008;358:1346-1353