Purpose: To examine the extent, nature and determinants of medication use in early pregnancy.
Methods: We reviewed early pregnancy medication use, as reported to a midwife at the booking interview, in women delivering between 2000 and 2007 in a large maternity hospital in Dublin, Ireland (n = 61 252).
Results: Excluding folic acid, at least one medication was reported in 23 989 (39.2%) pregnancies. Over the counter (OTC) medications were reported in 11 970 (19.5%) pregnancies, illicit drugs or methadone in 545 (0.9%) and herbal medicines/supplements in 352 (0.58%). FDA category D and X medications were reported by 1532 (2.5%) and 1987 (3.2%) women. Asthma, depression and hypertension were among the most commonly reported chronic medical disorders. Medications with potential for foetal harm were reported by 86 (15.7%) women treated for depression and 68 (20%) women treated for hypertension. Factors associated with reporting the use of medications with potential for foetal harm included unplanned pregnancy (adjusted odds ratio [aOR] 1.31, 95% confidence interval [CI] 1.12-1.52), booking at less than 12 weeks gestation (aOR 1.83, 95%CI 1.58-2.13), being above 25 years of age, unemployed (aOR 2.58, 95%CI 2.03-3.29), nulliparous (aOR 1.41; 95%CI 1.22-1.63), single (aOR 1.28; 95%CI 1.06-1.54) or smoking during pregnancy (aOR 1.96, 95%CI 1.67-2.28).
Conclusions: Women frequently report medication use in early pregnancy. Women and prescribers need to be aware of the lack of pregnancy safety data for many medications, and the need for pre-pregnancy planning. Prescribers should ensure that optimal medications are used when treating women of childbearing potential with chronic medical disorders.