Cervix Length at Mid-Pregnancy May Predict C-Se...(' understanding of what happens to a wom...),Health

The study, published in the March 27 issue of the New England Journal of Medicine, included almost 25,000 women who had their cervical length measured at 23 weeks of gestation using transvaginal ultrasound.

Caesarean rates were highest among those women with the longest cervix measurements. The women whose cervical measurements were between 40 and 67 millimeters long had a 25.7 percent C-section rate, compared to a 16 percent rate in those with the shortest cervical measurements -- 16 to 30 millimeters. C-section rates were 18 percent and 22 percent for the third and fourth quartile cervix measurements, respectively.

That translates to an 80 percent increased chance of a Caesarean section for a woman with the longest cervical measurements, according to the study.

"Studies in a number of species have suggested that the uterus prepares for labor well in advance of term. However, this is the first major study to suggest that the same is true in women," Smith said.

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To get advice on steps to take for a healthy pregnancy, visit the U.S. National Women's Health Information Center.

SOURCES: Gordon C.S. Smith, M.D., Ph.D., head, obstetrics and gynecology, Cambridge University, United Kingdom; Robert Lorenz, M.D., director, maternal-fetal medicine, Beaumont Hospital, Royal Oak, Mich.; Miriam Greene, M.D., obstetrician and gynecologist, New York University Medical Center, and clinical assistant professor, New York University School of Medicine, New York City, and co-author of Frankly Pregnant: A Candid, Week-by-Week Guide to the Unexpected Joys, Raging Hormones and Common Experiences of Pregnancy; March 27, 2008, New England Journal of Medicine