Fine-tuning cesarean risk.

The risk that a woman will require a cesarean the first time she gives birth varies widely, but some measures that are easily assessed early in labor may be key factors. (1) In a case-control study of 325 nulliparous women who delivered in a Colorado hospital in 1998-2001, five factors that were known within two hours of admission were independently associated with the risk of cesarean: A woman's likelihood of having a cesarean increased with her weight (odds ratio, 1.02) and with gestational age (1.1), and was sharply elevated if she had preeclampsia (5.8); the more the cervix dilated and the more progress the fetus made along the birth canal in two hours, the lower the likelihood of this outcome (0.5 and 0.6, respectively). The researchers divided the women into five groups of equal size on the basis of scores calculated from these results; they round that only 5% of women in the group with the lowest scores had cesareans, compared with 86% of those in the highest-scoring group. As the researchers acknowledge, the predictive ability of their model needs to be confirmed. However, they add, if it is validated, the model "would be easy to use during labor and delivery," and could help "avoid the pitfall of proceeding with a long labor or a failed operative vaginal delivery" among women with the greatest risk of requiring a cesarean.

(1.) Wilkes PT et al, Risk factors for cesarean delivery at presentation of nulliparous patients in labor, Obstetrics & Gynecology, 2003, 102(6):1352-1357