Drug use during early pregnancy the impact of maternal illness, outcome of prior pregnancies and socio-demographic factors

Socio-demographic factors have been associated with drug use in pregnancy. However, information on maternal illness has rarely been included in previous studies. The aim of this study was therefore to estimate the impact of maternal illness and prior pregnancy outcome on the use of analgesics/antipyretics, anti-infectives and antihistamines in early pregnancy controlling for socio-demographic factors. One thousand nine-hundred and forty-five parous pregnant women from Norway and Sweden were included in an interview study. Information on drug use, obstetric history, maternal illness and socio-demographic factors was collected by specially trained midwives at gestational week 17 and form the basis for the present analyses. After control for socio-demographic factors, reported illness was associated with the use of analgesics/antipyretics, anti-infectives and antihistamines during early pregnancy. The use of analgesic/antipyretic and anti-infective drugs differed between study sites. Sociodemographic factors such as age, parity, marital status, education, occupation and smoking habits did not influence drug use in the multivariate analysis. Maternal illness during pregnancy was associated with drug use in early pregnancy. When studying factors related to drug use during pregnancy, it is important to include information on maternal illness. Socio-demographic factors may be confounders and lead to erroneous conclusions about the factors related to drug use.