Second-hand smoke during first trimester ups CHD risk in infants

Mothers exposed to environmental tobacco smoke (ETS) during the first trimester of pregnancy are more likely to give birth to infants with congenital heart defects (CHD), a recent study has found.

Researchers conducted a case-control analysis of 749 foetuses with CHD and 880 foetuses without. Logistic regression analysis revealed that ETS exposure from 12 months before pregnancy through the first trimester increased the odds of CHD by nearly 70 percent (adjusted odds ratio [OR], 1.67, 95 percent confidence interval [CI], 1.28–2.18).

Such ETS exposure patterns increased the likelihood of septal defects (adjusted OR, 1.58, 95 percent CI, 1.18–2.12), conotruncal defects (adjusted OR, 1.86, 95 percent CI, 1.21–2.84), left ventricular outflow tract obstructions (adjusted OR, 1.69, 95 percent CI, 1.15–2.48), right ventricular outflow tract obstructions (adjusted OR, 1.82, 95 percent CI, 1.25–2.67), and other CHD types (adjusted OR, 2.73, 95 percent CI, 1.65–4.51).

Of note, ETS exposure had a dose-response effect on offspring CHD risk. Exposure levels below 1 hour per day did not affect the likelihood of developing CHDs, but exposure for 1–2 hours per day (adjusted OR, 1.60, 95 percent CI, 1.07–2.41) and ≥2 hours per day (adjusted OR, 4.94, 95 percent CI, 2.43–10.05) aggravated such risk.

“These findings highlight the importance of prescheduled pregnancy and prevention, including folic acid supplementation, paternal smoking cessation, maternal avoidance from ETS and hazardous noxious substances at home or workplace,” the researchers said.