Regression analyses for prenatal maternal anxiety and birthweight
First, as shown in Table 2-A, the maternal anxiety score at the 17th week was associated with birthweight. A stronger association was found for those reporting symptoms in the 30th week. Children exposed to maternal anxiety prenatally, as reported at both the 17th and 30th gestational weeks, were at higher risk of low birthweight compared to those not exposed and those exposed only once during pregnancy. This association was reduced, but remained, after adjusting for smoking and alcohol consumption. In addition, adjustments for potential confounders at steps 2 and 3 found the association to be weaker but still significant.
Sibling-comparison analyses found maternal anxiety to be associated with low birthweight when reported in only the 17thgestational week and in only the 30th gestational week. Children exposed to maternal anxiety as reported in both the 17th and 30th gestational weeks were at the highest risk of low birthweight, even after shared-family confounding was adjusted for. This association remained robust after adjusting for smoking and alcohol intake during pregnancy. However, the association was no longer significant when the birth-related and socio-demographic variables were controlled for.