One in five Los Angeles women smoke; some of them are trying to achieve a pregnancy, and some are undergoing infertility treatment. Most women are aware that smoking during pregnancy is harmful to the developing fetus; however, a new study has reported that, compared to nonsmokers, women who smoke in the months before undergoing infertility treatment are at a greater risk of delivering low-birth-weight and even very-low-birth-weight infants than nonsmokers. The findings were presented at the American Public Health Association 139th Annual Meeting, which ran from October 29 through November 2. Researchers from the Center for Maternal and Child Health, Maryland Department of Health and Mental Hygiene (Baltimore) reviewed data from a random sample of 14,194 mothers who delivered live infants from 2001 to 2009 and completed the Maryland Pregnancy Risk Assessment Monitoring System survey. The researchers identified women who became pregnant using fertility drugs, insemination techniques, assisted reproductive technology (ART), or other methods. They also obtained data on smoking status during the three months prior to pregnancy.
Of the study group, 5% reported undergoing fertility treatments, and 5% of those reported smoking prior to pregnancy. Among women who underwent fertility treatment and smoked, the prevalence of low-birth-weight infants was 24%; among the nonsmoking women, it was 14%. In addition, smokers who delivered twins were more than six times more likely to have low-birth-weight infants than nonsmokers. When the researchers adjusted for maternal age, race/ethnicity, multiple pregnancy, and smoking during pregnancy, women who smoked during pregnancy were three times more likely to have a low-birth-weight infant than nonsmokers, and were four times more likely to deliver a very-low-birth-weight infant (< 1,500 grams (3 lbs, 5 oz)).
Lead author Lee Hurt, MS, MPH noted that, considering the unique level of planning typically involved in assisted reproduction, the smoking rates were unexpected. She said, “The rate of women who smoked while using fertility treatments was surprisingly high,” adding that rates of smoking dropped off during pregnancy; however, they did not reach zero. She further explained, “Smoking prevalence before pregnancy among all mothers typically drops in half, from 18% to 9.5%, during pregnancy; we saw a similar reduction during pregnancy among women receiving fertility treatments, from 5.5% before pregnancy to 3% during pregnancy.” She noted, “A limitation of the study is that it doesn’t indicate how much time before a pregnancy a women needs to stop smoking, but if you look at the life cycle, it’s clear you want to try to convince women to stop smoking as soon as possible before they even consider getting pregnant.”
