Prescription drugs during pregnancy and lactation--a Finnish register-based study

Abstract

Objective: To examine the use of prescription drugs in Finnish women before and during pregnancy and lactation.

Methods: A register-based study linking four nation-wide registers in Finland: the Maternal Grants Register, the Drug Prescription Register, and the Special Refund Register (all maintained by the Social Insurance Institution in Finland; KELA), and the Finnish Population Register. The study included all women applying for maternity support (maternal grants) during the year 1999, and non-pregnant control women matched by age and hospital district. Data collection included the number and type of prescription drugs purchased by the two cohorts during preconception (3 months before pregnancy), each trimester, and lactation.

Results: Of the 43,470 pregnant women, 46.2% purchased at least one drug and 12.7% three or more different drugs during pregnancy. Corresponding proportions for the control cohort were 55.2% (OR 0.7, 95% CI 0.6-0.7) and 23.0% (OR 0.5, 95% CI 0.5-0.5). The drugs most frequently purchased during pregnancy were systemic antibiotics (24.1% of pregnant women vs 27.3% controls; OR 0.8, 95% CI 0.8-0.9) and gynaecological anti-infective agents (8.3% vs 1.5%; OR 5.5, 95% CI 5.5-6.5). For pregnant women, purchases of most drug groups had already declined during the first trimester, but no reduction was apparent in drugs for chronic illnesses (epilepsy, asthma, diabetes).

Conclusions: Although drugs were purchased abundantly during pregnancy, a significant decline occurred for most drug groups. The medication pattern for chronic illnesses remained unchanged. The purchase of several different drugs was relatively common and raises concerns.