Babies of Non-Smoking Pregnant Women at Risk from Secondhand Smoke Exposure
It is widely known that smoking during pregnancy can cause a multitude of health risks for both mother and baby. New research shows that even non-smoking mothers who are exposed to secondhand smoke are at an increased risk of serious effects, including stillbirth and major birth defects.
Secondhand Smoke Exposure Increases Risk of Stillbirth and Congenital Malformations
Smoking during pregnancy exposes the baby to dangerous chemicals such as nicotine, carbon monoxide, and tar. The baby is also deprived of oxygen, which is important for fetal growth. Women who smoke are more likely to have an ectopic pregnancy, vaginal bleeding, placental abruption, placenta previa, and stillbirth. Babies born to smoking women are more likely to have birth defects such as cleft lip or palate, low birthweight, and prematurity which increases the risk of lifelong disability.
Dr. Jo Leonardi-Bee PhD MSc of the Center for Tobacco Control Studies at the University of Nottingham reviewed and analyzed 19 studies from North America, South America, Asia and Europe. The studies focused on pregnant women who did not smoke but were exposed to secondhand smoke at home or at work.
Four of the studies found a 23% increased risk of stillbirth with tobacco smoke exposure during pregnancy. Seven of the studies found that pregnant women exposed to secondhand smoke were 13% more likely to give birth to a child with congenital malformations. These included heart defects, clubfoot, neural tube defects, ancephaly, orofacial clefts, and craniosynostosis (skull deformity).
Prior research conducted by Leonardi-Bee’s team found that maternal exposure to secondhand smoke decreased infant birth weights by 33 grams (1.16 oz) and increased the risk of having a low birthweight baby. Secondhand smoke exposure has also been linked to a greater risk of infant death due to SIDS and damage to baby’s lungs which can lead to asthma and other respiratory ailments.
"Because the timing and mechanism of this effect is not clear, it is important to prevent secondhand smoke exposure in women before and during pregnancy," the group urged in their paper. Leonardi-Bee also note that active smoking by the father could damage genes in his sperm which impact the unborn child’s health.
Leonardi-Bee J, et al "Secondhand smoke and adverse fetal outcomes in nonsmoking pregnant women: A meta-analysis" Pediatrics 2011; DOI: 10.1542/peds.2010-3041.