Negative influence of maternal smoking during pregnancy on infant outcomes

According to the INPES 2014 health barometer, the prevalence of smoking in pregnant women in France is the highest in Europe : 17.8% of expectant mothers who smoke continue to do so during pregnancy. Several epidemiological studies have confirmed multiple risks for tobacco-exposed infants (low birth weight; digestive, respiratory, neurological, and psychological disorders; obesity; type 1 diabetes).

This study compared a cohort of infants exposed to tobacco in utero (T+) with those unexposed (T-). Birth weight, diet, presence of colic (ROME III criteria) and regurgitations (Vandenplas scale) were specifically analyzed.

This observational, cross-sectional, and multicenter survey was conducted in France by pediatricians and general practitioners from September 2016 to February 2017. Infants with a chronic pathology and those with parents under 18 years of age were excluded. The data were collected by the physician and by the mother through a self-administered questionnaire.

A total of 452 physicians recruited 759 T+ and 741 T- infants in the study. The mean birth weight of T+ infants was significantly lower (3.1±0.5 kg [WHO z-score -0.476±1.081]) than that of T- infants (3.3±0.5 kg [0.033±0.965]; P<0.001). At the time of leaving the maternity facility, 47.7% of T+ infants were breastfed by their mother compared with 70.1% of T- infants. The median reported duration of breastfeeding was 1 month vs. 2 months for T+ and T- infants, respectively. Colic was significantly more common in T+ than in T- infants: 25.6% vs. 12.3% according to the ROME III criteria, and 45.7% vs. 29.7% according to the doctor's opinion (P<0.001 for both). In the T+ group, cases of regurgitation (63.6% vs. 56.5%; P=0.005), respiratory disorder (6.3% vs. 2.4%, P<0.001), and bronchiolitis (6.5% vs. 3.0%; P=0.001) were also more frequent.

This study confirms that maternal smoking during pregnancy is associated with health risks; exposed infants had significantly more digestive/respiratory symptoms and lower birth weight than unexposed infants. Preventive and educational actions need to be further strengthened in the face of this public health problem.