Antibiotics in pregnancy--a prospective cohort study on the policy of antibiotic prescription.

Pregnancy is associated with special problems with respect to antibiotic selection and dosage due to potential teratogenic or toxic effects on the fetus by the drug itself, and the great physiological adjustments in the mother. This survey was designed to record the use of antibiotics and the policy of prescription of antimicrobial drugs during the course of pregnancy. In total, 4055 pregnant women residing in a county in south-western Finland during the period June 15, 1987-June 14, 1988 were studied. Penicillin, erythromycin and pivmecillinam were the most often used antibiotics during pregnancy comprising together 65.4% of all antibiotic use; 94.1% of all antimicrobial medication was administered orally. The highest incidence for antibiotic use (45.4% of all) as well as for treated infections (45% of all) was at the second trimester. The duration of medication was commonly 10 days (44.4%, SD 14.6) or 7 days (27.9%, SD 7.7). Penicillin was in a few cases prescribed at increased dosage (25.6%), while erythromycin and amoxicillin were occasionally administered at reduced dosages (30.2% and 42.5%, respectively). The dosages should probably be individualized more often, according to the information available on the pharmacokinetics of specific antibiotics during pregnancy. It may also be possible to reduce the length of antibiotic treatment for UTI.