Podcast: Mothers pass smoking on to daughters

The podcast is available at http://www.nichd.nih.gov/news/releases/Documents/NICHD_Research_Dvlpmts_041714.mp3 (MP3 - 5.6 MB).

Ms. Lazeration: Do parents realize that they influence their children’s lifestyles before birth? A recent study funded by the National Institutes of Health found that mothers who smoke are likely to pass the habit on to their daughters. In addition, mothers who are stressed and producing more stress hormones are even more likely to pass on the deadly habit.

The study, led by Dr. Laura Stroud, followed 1,100 mothers during pregnancy and interviewed their children in adulthood. From the National Institutes of Health, I am Rebecca Lazeration, and this is Research Developments, a podcast from the NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, the NICHD.

With me now is Dr. Laura Stroud, a senior research scientist at Miriam Hospital and an associate professor of psychiatry and human behavior at Brown University’s Alpert Medical School. Thank you for joining me today, Dr. Stroud.

Dr. Laura Stroud: My pleasure. Thanks for having me.

Ms. Lazeration: Now, smoking has declined in recent years. Is smoking during pregnancy still a big problem today?

Dr. Stroud: It remains a problem, although rates, when we ask mothers, on national surveys, the number of certificates have gone down. Mothers are continuing to smoke, and it’s particularly a problem in low-income, less-educated mothers with unplanned pregnancies.

Ms. Lazeration: Now, how does maternal smoking during pregnancy affect the baby?

Dr. Stroud: There’s a large number of studies showing multiple effects on infants and later throughout the lifetime. Its primary, sort of, medical effect is on low birth weight. There’s some associations with premature birth. And then what we’ve been interested in is, over the lifetime, there appears to be increased risk of behavioral problems, and in this case, we’re focused on increased risk for nicotine dependence, or nicotine addiction.

Ms. Lazeration: In your study, you wanted to learn how smoking during pregnancy might increase the child’s risk of smoking as an adult. How was this done?

Dr. Stroud: So, this was a long-term longitudinal study, about 40 years in duration, based on the National Collaborative Perinatal Project that was funded many years ago by the National Institutes of Health. Data was collected between 1959 and 1966 on mothers who were pregnant during that time. We had this cohort of approximately 1,000 women who were followed through the New England Family Study until approximately 40 years of age. And we interviewed the mothers about their nicotine dependence and a number of other factors at approximately 40 years.

And during pregnancy, we had data on mom’s levels of smoking across pregnancy, and we also had serum that has been stored at the National Institutes of Health since their pregnancies between 1959 and 1966. So we were able to take serum, or blood, out of storage and actually look at stress hormones and measure the nicotine levels in the mom’s blood.

Ms. Lazeration: And what were the results that you found?

Dr. Stroud: We found that smoking during pregnancy itself, particularly smoking 15 or more cigarettes per day during pregnancy, was associated with approximately 50 percent increased risk of offspring smoking in the daughters of moms who smoked during pregnancy. So, the daughters of moms who smoked during pregnancy showed 50 percent increased risk of nicotine dependence 40 years later.

The other factor that we found was critical to onset of moms smoking was cortisol, which is a stress hormone, which was measured during pregnancy, during the third trimester of pregnancy, and cortisol was associated with approximately a 13 percent increased risk of nicotine addiction in the daughters.

So together, the moms being exposed to both mom smoking during pregnancy and mom’s increased stress hormones was a double hit in terms of predicting mom’s increased risk of nicotine addiction.

Ms. Lazeration: Now, why would smoking during pregnancy affect daughters but not sons?

Dr. Stroud: Well, that’s something that we’re interested in doing more research on. There’s been some animal studies that have showed particular effects on one gender or the other. There’s been a number of studies showing effects on either one gender or the other. They’re not 100 percent consistent, so we’re very interested in following up on that finding and trying to understand why it might affect daughters more than sons.

Ms. Lazeration: Now, if a woman who smokes finds out that she’s pregnant, is it too late for her to quit, or can she and her baby still benefit from quitting later in the pregnancy?

Dr. Stroud: Definitely. Mothers and babies have been shown to show improvement. Birth weight can be regulated back to normal after moms quit during pregnancy. So, benefits of quitting have been shown at, you know, in multiple studies. So it’s never too late to quit, and even after the baby is born, quitting can protect the baby from secondhand smoke exposure.

Ms. Lazeration: Do you have any advice for pregnant smokers who want to quit?

Dr. Stroud: Well, there’s a number of places to go online. Talk to your doctor, continue to talk to your doctor and ask your doctor for ideas for quitting smoking. Gather support from folks around you; try to set a quit date; do anything you can to try to help yourself quit, because you’re quitting both for yourself and for your baby. And the other advice would be to stay quit after the baby’s born.

Ms Lazeration: Thank you so much for speaking with me today, Dr. Stroud.

Dr. Stroud: Certainly. My pleasure.