A new study published in the online journal Biological Psychiatry provides the first evidence that prenatal exposure to the stress hormones glucocorticoids predicts smoking and nicotine dependence later in life among women. The study confirmed previous research on prenatal smoking, and suggested that this increased risk of nicotine addiction is the result of exposure to increased levels of stress hormones in mothers during pregnancy. Laura Stroud, Ph.D., from the Centers for Behavioral and Preventative Medicine at The Miriam Hospital, led the study. Stroud and her team gathered data from 1,086 pairs of mothers and their adult children. “While maternal smoking during pregnancy has been shown to be an independent risk factor for nicotine dependence, we didn’t really know –- until now –- which pathways or mechanisms were responsible, Stroud said. “Most prior research involving biological mechanisms had been conducted in animals not humans.” The mother and child pairings were selected from the participants in the 40-year New England Family Study project, which was a long-term follow-up to the Collaborative Perinatal Project created by Brown University in Providence, Rhode Island. The average age of the adult children selected for Stroud’s research was 39, and 59 percent of the adult child subjects were female. Stroud’s study found that exposure to higher rates of high-stress hormones known as glucocorticoids in utero left daughters more vulnerable to developing a nicotine addiction later in life. Women who smoked were more likely to experience high levels of stress, and to live in adverse conditions that bred stress, and as a result they were more likely to have higher levels of the glucocorticoid hormones. This study is not the first to provide evidence that the adult children of women who smoked during pregnancy are at higher risk for nicotine addiction. However, Stroud’s study confirms earlier research findings and is the first to provide a possible chemical explanation for why this greater risk exists. As part of the original Collaborative Perinatal Project from Brown University, the mothers in the study were assessed for nicotine use during prenatal visits. Levels of hormones in the blood including cortisol, testosterone and cotinine were evaluated during the third trimester. For the Stroud study, the smoking habits of the now adult children were assessed during interviews. Among the 1,086 pairs of mothers and adult children evaluated for the study, the adult daughters who were exposed to high levels of glucocorticoids in utero had a 13 percent higher risk of nicotine dependence. The daughters of women who smoked at least 15 cigarettes per day had a 52 percent higher risk of nicotine dependence. Many Health Risks from Prenatal Smoking The findings from Stroud’s study add to the large volume of research that shows the importance of a woman’s health during pregnancy. Her health can affect not only the immediate health and development of a newborn infant, but also the long-term health and development of an individual throughout childhood, adolescence and adulthood. Increased risk of nicotine addiction is only one of the more recently discovered in a long line of health risks associated with prenatal smoking. Over the years, research has shown that people whose mothers smoked during pregnancy are at greater risk of a laundry list of problems, including adolescent drug dependence, behavior problems, conduct disorders, attention-deficit hyperactivity disorder (ADHD), irritability and criminal arrest. The many health risks associated with smoking, stress, or other health problems during pregnancy highlight the importance of maternal health when it comes to ensuring that children are also healthy. Improving the overall health of women before, during and after pregnancy will help to ensure that more children are born healthy, and that fewer children develop serious physical and mental health problems as they get older. One of the more surprising results of the study was the fact that the increased risk of nicotine addiction only affected the adult female children in the study. The reason for this gender bias is not fully understood. It may have something to do with the different ways in which men and women regulate hormones, or men and women may adapt differently to environmental factors in utero. It is also possible that glucocorticoid hormones and nicotine affect male and female brains differently. The finding is concerning because it carries the possibility of multi-generational complications from a single case of prenatal smoking. If a woman smokes during pregnancy, a daughter would be at greater risk of smoking, and if she in turn smoked during pregnancy, the pattern could continue.