Guidelines and methodological standards for smoking cessation intervention research among pregnant women: improving the science and art.

While the evidence confirming the risks of smoking during pregnancy is unequivocal, smoking rates for U.S. women remain high. From 1965 to 1975 the proportion of women smokers, aged 18 to 35, rose from 34% to 36%. Rates of heavy smoking increased from 51% to 61%. Significant increases were noted in the United States, especially for teenaged girls, with 1979 data showing higher smoking rates among girls aged 17 to 18 (26%), than among the same-aged boys (19%). Moreover, adolescents have one-fifth of all U.S. births. Exact rates of smoking during pregnancy are unknown but several reports suggest 20-40% of pregnant U.S. women smoke at the onset of pregnancy. A national survey showed 35% of young women smokers able to quit smoking during pregnancy, with another 32% cutting down. Although 62% believed that smoking could harm the fetus, the majority were unable to stop smoking during their pregnancy. Most women who succeed in quitting or cutting down revert to their usual smoking habits late in pregnancy or after delivery. Since almost all data are based on self-reports, some degree of inaccuracy and underreporting can be assumed.