Secondhand smoke exposure linked to pregnancy loss

Secondhand smoking is linked to pregnancy loss, including miscarriage, stillbirth and tubal ectopic pregnancy, according to new research.

Scientists at Roswell Park Cancer Institute (RPCI) and the University at Buffalo (UB) collected data from more than 80,000 women from the Women's Health Initiative Observational Study.

"As a result of the Women's Health Initiative Observational Study, participants came from a broad range of geographic areas and had multiple ethnic, educational and socio-economic backgrounds," co-author Dr. Jean Wactawski-Wende, professor in the Departments of Social and Preventive Medicine and Obstetrics and Gynecology at UB, said in a statement. "This allowed for a comprehensive assessment of detailed information on exposures, outcomes and potential confounders."

This study looked at secondhand smoke (SHS) exposure over a person's lifetime rather than just during pregnancy or reproductive years, taking into account smoke exposure during one's childhood and adult years. Past studies showed evidence that smoking during pregnancy was associated with these three outcomes of fetal loss, but less on secondhand smoking.

Women with the highest levels of SHS exposure - despite never having smoked themselves - had significantly greater risk of miscarriage, stillbirth and tubal ectopic pregnancy. These risks were almost on par with the risks associated with women who smoked more than 100 cigarettes in their lifetime. Those who were exposed to SHS for more than 10 years during childhood, more than 20 years during adulthood and more than 10 years in the workplace showed the highest SHS exposure levels.

The study's lead investigator notes this analysis as a breakthrough in understanding the adverse effects of secondhand smoking.

"This study offers new information for women regarding the lifetime impact secondhand smoke can have on reproductive outcomes and their ability to successfully bring a pregnancy to full term," said Dr. Andrew Hyland. "The strength of the study also provides public-health professionals and others with information upon which to base health guidelines about the significant consequences of secondhand smoke."