Considerations for smoking advice in pregnancy.

Cigarette smoking in pregnancy was the single most important preventable factor identified when determinants of birth weight were studied in 375 pregnancies. Current professional intervention was not effective in reducing cigarette consumption in pregnancy in these mothers in Londonderry, of whom only 19 (5%) became ex-smokers. Present health education, which emphasises impaired fetal growth and wellbeing, had its greatest effect amongst primigravid smokers of whom 32% made some reduction in cigarette consumption. Maternal expectation of birth weight differed significantly between non-smokers, light to moderate, and heavy smokers (8.2 lb, 7.9 lb, 7.3 lb respectively). 54% of multiparous smokers expected the birth weight to be similar to the birth weight in previous pregnancies. Of the women who reduced smoking, 57% did so for the baby, 23% because they found the habit less pleasurable during pregnancy and 13% because of professional advice. Maternal expectation of birth weight is one factor which negates the slant of current health education advice in pregnancy. An anti-smoking programme aimed at protecting the fetus from the harmful effects of cigarettes may produce optimal results when targeted at primary school-aged children in whom the smoking habit is less firmly established.