Objective: 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.
Study design: 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 in vivo by collagen light-induced fluorescence (LIF), and cervical resistance to stretch was measured by in vitro extensibility tests.
Results: 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 in vitro had little effect on uterine contractility.
Conclusion: Nicotine exposure during pregnancy prolongs gestation and inhibits cervical ripening, possibly by suppression of a cholinergic antiinflammatory response.
Keywords: cervical ripening; collagen cross-links; fetal outcome; inflammation; nicotine; pregnancy; smoking.
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