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Pharmacoepidemiol Drug Saf. 2010 Apr;19(4):408-17. doi: 10.1002/pds.1906.

Medication use in early pregnancy-prevalence and determinants of use in a prospective cohort of women.

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Coombe Women and Infants University Hospital, Dublin, Republic of Ireland.



To examine the extent, nature and determinants of medication use in early pregnancy.


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).


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).


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.

[Indexed for MEDLINE]

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