The Problem of Confounding in Studies of the Effect of Maternal Drug Use on Pregnancy Outcome
Table 5
Importance of maternal education or non-cohabitation for occurrence and diagnosis of congenital malformations in Sweden. Odds ratios (ORs) with 95% confidence intervals (95% CI) for various malformation groups at different maternal education levels. For educational level, the reference is 12 years of education, for non-cohabitation, the reference is cohabitation. Adjustment for year of birth, maternal age, parity, smoking, and BMI.