A trial of health education aimed to reduce cigarette smoking among pregnant women.

Three hundred and forty-six women who reported smoking one or more cigarettes per day prior to the 20th week of gestation were recruited into a trial of health educational counselling to stop or reduce cigarette smoking. Counselling was begun at the first prenatal visit and then continued subsequently in the home. Among the 319 women included in analysis, at first follow-up visit those who received counselling smoked 1.7 fewer cigarettes a day than control women (P less than 0.05) and 10.4% had stopped smoking, compared to 5.4% in the control group (NS). Similar but not significant differences were noted at the end of pregnancy. Study effects were limited to the 284 women smoking five or more cigarettes a day at booking. This report refers primarily to them. At first follow-up visit the proportion of such women in the counselled group who ceased smoking (9.3%) was significantly greater than in the control group (2.6%; P less than 0.05). The magnitude of this difference persisted through late pregnancy (11.8% vs. 4.3%; NS) and delivery (10.6% vs. 4.7%; NS). The differences between counselled women and controls in numbers of cigarettes reported smoked at first and last prenatal follow-up visits (2.4 and 2.1) and at delivery (2.0) were all statistically significant. While there was no effect of counselling on either serum thiocyanate or end expiratory carbon monoxide, the counselled group gained slightly more weight than controls during the study (0.47 vs. 0.44 kg per week among controls; NS), and their infants had modestly higher birthweight (44 g; NS).