Maternal plasma leptin levels in relation to the duration of the active phase of labor.

Abstract

Obese women have increased leptin levels and longer duration of labor compared with normal-weight women. Leptin has an inhibitory effect on myometrial contractility in vitro. Our purpose was to examine whether maternal leptin levels in active labor were associated with the duration of the active phase of labor. This prospective cohort study included 914 women. Maternal blood samples were collected in active labor. The plasma-leptin concentration was obtained using a direct sandwich-based ELISA. Bivariate and multiple linear regression analyses were used to study the association between leptin levels and the duration of labor. A 1ng/mL increase in maternal plasma leptin was associated with a 0.015hour increase in duration of labor (P<.007). This association was not statistically significant in the adjusted analyses nor when analyzing nulliparous and multiparous women separately. In women with spontaneous labor (n=766) leptin levels were not associated with an increase in duration of labor in the adjusted analyses. There was no significant association between leptin levels and duration of the active phase of labor. Leptin in vivo might display a similar dose-response effect on myometrial contractility as demonstrated in in vitro studies. Future studies need to explore the association between leptin levels and time in labor in obese women with high leptin levels to evaluate a possible dose-response effect.