Nicotine treatment prolongs gestation and inhibits cervical ripening in pregnant rats

Abstract

The aims of this study were to examine the effects of nicotine treatment on the length of gestation, on fetal outcome, on cervical ripening, and on uterine contractility during pregnancy in rats. Pregnant rats were treated with various concentrations of nicotine (0.25, 0.5, 1, 2 mg/kg/d, subcutaneously). Delivery times and fetal weights were obtained. Cervical collagen cross-links were assessed invivo by collagen light-induced fluorescence (LIF), and cervical resistance to stretch was measured by invitro extensibility tests. Delivery time is significantly (P= .002) prolonged after high-dose nicotine treatments. There are no significant changes in pup weights and placenta weights after nicotine treatments. Cervical collagen LIF and extensibility progressively decrease throughout pregnancy in control rats. Nicotine-treated rats showed significant (P< .001) cervical resistance to stretch and higher LIF compared with the control rats. Nicotine treatment invitro had little effect on uterine contractility. Nicotine exposure during pregnancy prolongs gestation and inhibits cervical ripening, possibly by suppression of a cholinergic antiinflammatory response.