Medication Use During Pregnancy: Data from the Avon Longitudinal Study of Parents and Children

Objective: To present data on the self-reported use of all types of medicinal products collected during pregnancy in a large cohort in southwest England.

Methods: Pregnant women with a delivery date during 1991-1992 and forming part of the prospective, population-based Avon Longitudinal Study of Parents and Children (ALSPAC) were sent up to four self-completion postal questionnaires during pregnancy. Text data collected from the questions on drug usage were coded using an ALSPAC drug dictionary based on the World Health Organization Drug Dictionary.

Results: At least one antenatal self-completion questionnaire was completed for 14,119 pregnancies, and 11,545 women completed all four. The data included prescription, over-the-counter, herbal and homeopathic products as well as iron, vitamins and other supplements. Only 7.6% did not report use of any medicinal product throughout their entire pregnancy. The remaining 92.4% used at least one product at some stage. After exclusion of iron, folate, vitamins, supplements, herbal and homeopathic products and skin emollients, 83% of those completing all questionnaires had used conventional therapeutic drugs. Analgesics were reported by approximately one-third of women at each stage during pregnancy, and paracetamol was the most frequently reported substance. Iron preparations were reported by 33% of the full cohort, at some stage, and folate by 21.9%. Use of anti-anaemic products increased during pregnancy with the greatest incidence at 32 weeks. Other vitamins and supplements were taken by 17.4% at some stage. Use of vitamins decreased throughout pregnancy from 9.6% in early pregnancy to 5% at 32 weeks. Antacids were reported by 23% at 32 weeks. The reported incidence of antibiotic use decreased slightly during pregnancy from 8% early on to 5.8% at 32 weeks; amoxicillin was the most frequently reported antibacterial.

Conclusion: Use of medicinal products was high during pregnancy in the ALSPAC cohort. This finding is consistent with data from recent publications.