Background:
Numerous human studies have investigated potential teratogenic effects of maternal smoking during pregnancy, with conflicting findings [1, 2]. One of the most common birth malformations is congenital heart defect (CHD) with a prevalence of around 1% of live births [3, 4]. More specifically, several studies indicate that maternal tobacco use is related with increased risk of CHD, whereas other studies do not find any association [5, 6]. The aim of this study is to systematically review the literature regarding the correlation between maternal smoking during pregnancy and the prevalence of CHDs in offspring.

Methods:
A thorough up-to-date search of the English literature through PubMed identified studies of maternal smoking during pregnancy and CHD in infants. The selected Mesh terms included ”maternal”, “tobacco”, “smoking”, ”cigarette”, “pregnancy”, “cardiovascular”, “abnormalities” ”congenital abnormalities”, “congenital heart defect”, ”offspring”. The main parameters that were extracted from the eligible studies were maternal characteristics (age, weight, race, socioeconomic and health status), smoking habits (cigarettes per day, fetal exposure period) and CHD subtypes.

Results:
The systematic search identified 874 articles, of which 37 met the inclusion criteria. Most studies have shown a strong correlation (OR: 2.06; 95% CI: 1.20–3.54) between mothers who reported medium and heavy smoking (≥1 pack per day) during the first semester of pregnancy and infants with septal heart defects than women who did not smoke during this time period. Maternal age, weight and socioeconomic status are independent confounding factors for neonatal heart defects. Women who smoked ≥25 cigarettes per day had increased risk to have infants with right-sided obstructive defects compared with nonsmoking mothers. Infants with CHD were more likely to be premature and have lower birth weight than healthy infants.

Conclusions:
Maternal cigarette smoking during pregnancy is associated with congenital heart defects, especially with septal and right-side obstructive defects [7]. Additionally, future studies should take place in order to understand all underlying mechanisms and set the starting point of population-based prevention strategies so as to encourage more women to quit smoking before or early in pregnancy resulting in decreased infant mortality and morbidity.