Stop smoking for the next
generation
Tao Duan
Shanghai First Maternity and Infant
Hospital of Tongji University
Shanghai
China
Email: tduan@yahoo.com
Pregnancy provides optimal opportunities for health promotion and
disease prevention. Smoking before and during pregnancy is one of the
largest modifiable risk factors for a range of adverse pregnancy
outcomes. Concerns over the risks of smoking motivate many pregnant
smokers to quit. However, most of their partners continue to smoke
throughout pregnancy. More than one-third (35%) of men in the world
smoke, and just over 6% of women do (Ritchie et al. Published
online at OurWorldInData.org 2020). The impact of paternal smoking,
second-hand or third-hand smoking on the perinatal health is largely
overlooked. Given the vast majority of studies focusing on the pregnant
smokers, less is known about paternal smoking on their future children.
In this paper (Zhou et al. BJOG 2020), using a large national
prepregnancy registry database, Zhou et al. found that paternal smoking
may be associated with birth defects such as congenital heart diseases,
limb abnormalities and neural tube defects in the offspring. The result
was consistent with previous retrospective studies, but a medium to
large effect size was seen. All of the odd ratios exceeded 2.5, with one
even over 20 (congenital heart diseases OR=2.51, 95%CI 1.04-6.05; limb
abnormalities OR=20.64 95%CI 6.46-68.02; digestive tract anomalies
OR=3.67 95%CI 1.44-9.37; neural tube defect OR=4.87,95%CI 1.66-14.28).
Such difference might be partially explained by potential confounding
factors. For example, the extent of tobacco exposure, in the National
Birth Defects Prevention Study (Malik et al. Pediatrics 2008; 121:
e810), compared with light smoking exposure (<14 cigarettes
per day), heavy smoking women (≥25 cigarettes per day) were more likely
to have infants with septal defects (OR 2.06; 95%CI: 1.20-3.54),
suggesting a dose-dependent relationship between tobacco exposure and
birth defects.
In addition, a reduced risk of birth defects after changing smoking
behaviors was found in Zhou’s paper. It is no surprise that paternal
smoking cessation could improve the adverse outcomes. Limited evidences
address whether there is a critical window period by which smoking must
be stopped to prevent subsequent adverse perinatal outcomes. Results
from a retrospective case-control study indicated that the risk of fetal
congenital heart diseases increased as women smoked during the first
trimester (Sullivan et al. J Pediatr; 2015; 166:978). In a prospective
cohort study (McCowan et al. BMJ 2009; 338: b1081), the authors
concluded that stopping smoking early in pregnancy, and certainly by
15-16 weeks’ gestation, may minimize the adverse effects of smoking on
late pregnancy complications and should be an important goal for
pregnant smokers. Yet, such critical time for paternal smoking cessation
remains unknown.
Tobacco smoke is also a human germ cell mutagen. It is estimated that
with even a modest 25% increase in sperm mutation frequency caused by
smoke-exposure, for each generation across the global population there
will be millions of smoking-induced de novo mutations transmitted from
father to offspring (Beal et al. Mutation Research;2017; 773:26).
Therefore, it is strongly recommended that women and men should
immediately stop smoking in advance of reproduction.
No disclosures: A completed disclosure of interest form is
available to view online as supporting information.