(RxWiki News) Smoking tobacco during pregnancy has been linked to a host of prenatal and birth issues. Women don't even have to be a smoker to be at risk; secondhand smoke may pose a threat as well.
A recent study found that lifetime secondhand smoke exposure increased the risk of fetal loss during pregnancy.
The researchers suggested that their findings could help expand knowledge on the dangers of secondhand smoke and aid in the creation of new policies to protect women and their children.
"Tell your OB/GYN if you have been exposed to secondhand smoke."
The lead author of this study was Andrew Hyland, PhD, from the Department of Health Behavior in the Division of Cancer Prevention & Population Sciences of the Roswell Park Cancer Institute in Buffalo, New York.
The study used data on 77,805 participants from a previous study called the Women's Health Initiative (WHI) from 1993 to 1998.
All participants were postmenopausal women, aged 50 to 79 years old, who had been pregnant at least once and were receiving care from any of 40 different clinics across the country.
These women provided complete information on lifetime smoking status, secondhand smoke exposure and negative pregnancy outcomes during the WHI.
The researchers looked for instances of spontaneous abortion (when the fetus is lost before 20 weeks of pregnancy), stillbirth (fetus is lost between 20 weeks and full term of pregnancy) and ectopic pregnancy (when the embryo implants itself somewhere other than the uterus).
The women were categorized first as ever-smokers or never-smokers; then, the never-smoking group was split into two groups:
- Never-smokers with no lifetime secondhand smoke exposure
- Never-smokers with lifetime secondhand smoke exposure in their childhood home, adult home and/or adult workplace.
The never-smoking group consisted of 47 percent of the study's participants.
The findings showed that 25,386 participants (33 percent) had one or more spontaneous abortions, 3,364 participants (4 percent) had one or more stillbirths and 1,933 participants (2 percent) had one or more ectopic pregnancies.
Compared to the women in the never-smoking group, those in the ever-smoking group had a 16 percent increased risk of having a spontaneous abortion, a 44 percent increased risk of having a stillbirth and a 43 percent increased risk of having an ectopic pregnancy.
The researchers also found that the women in the never-smoking group who had the highest levels of secondhand smoke exposure were at a 17 percent increased risk for having a spontaneous abortion, 55 percent increased risk having a stillbirth and 43 percent increased risk of having an ectopic pregnancy compared to those in the never-smoking group with no secondhand smoke exposure in their lifetime.
The highest levels of secondhand smoke exposure in the non-smoking group were among the women with more than 10 years of secondhand smoke exposure in their childhood home, more than 20 years of exposure in their adult home and/or more than 10 years of exposure at work as an adult.
Dr. Hyland and colleagues noted a few limitations of their study. First, the participants may have under-reported lifetime tobacco exposure. Second, there was no data on secondhand smoke exposure while pregnant. Furthermore, home pregnancy tests were not available when the participants were of reproductive age, so this study included only fetal loss that was noticed by the participant.
This study was published on February 26 in Tobacco Control.
The National Heart, Lung, and Blood Institute, the National Institutes of Health and the US Department of Health and Human Services provided funding.