Nicotine patch use in pregnant smokers: nicotine and cotinine levels and fetal effects

The aims of this study were (1) to determine whether nicotine patch therapy for pregnant women smokers acutely compromises fetal well-being and (2) to determine the serum and urine nicotine and cotinine levels in pregnant women while smoking, while abstinent from smoking, and while receiving nicotine patch therapy compared with levels in a historical control group of nonpregnant women smokers who abstained from smoking while receiving comparable doses of nicotine patch therapy.

Pregnant cigarette smokers (n = 21) aged >/=18 years whose fetuses were beyond 24 weeks' gestational age were recruited for this 1-sample, repeated-measures study. Serial measurements of the mother and fetus were made at baseline while the mother was smoking, while abstaining from smoking, and while using nicotine patch therapy for 4 days in a special care hospital unit. Nonpregnant women smokers of similar age were used for comparison. Morning and afternoon serum and 24-hour urine levels of nicotine and cotinine were obtained during hospitalization. Indicators of fetal well-being assessed were fetal heart rate and reactivity, systolic/diastolic ratio of blood flow in the umbilical artery, and fetal activity seen on ultrasonography and quantitated as biophysical profiles.

No evidence of fetal compromise was seen during the inpatient phase while nicotine patch therapy was administered. Steady state (inpatient day 4) serum levels of nicotine were similar to smoking levels and to those seen in historical control subjects (ie, nonpregnant women of child-bearing age who were abstinent from smoking and who used the same nicotine patch). Morning serum cotinine levels were significantly higher (P =.038) in the nonpregnant subjects than in the pregnant subjects, whereas afternoon levels were not significantly different. Steady state urinary levels of nicotine and cotinine were also not significantly different in pregnant versus nonpregnant patients. On inpatient days 2, 3, and 4, when the women were not smoking and were wearing the nicotine patch, the morning fetal heart rates were significantly reduced relative to baseline when the subjects were smoking.

Nicotine patch therapy was not found to be associated with indications of fetal compromise during the in-hospital phase of nicotine patch therapy in pregnant smokers who were abstaining. Although not conclusive because of the small sample sizes, serum nicotine levels (morning and afternoon) appear similar in pregnant and nonpregnant subjects and similar for both groups when smoking (baseline) as compared to the steady state of nicotine patch use.