Prescription drug use among fathers and mothers before and during pregnancy. A population-based cohort study of 106,000 pregnancies in Norway 2004-2006

Abstract

What is already known about this subject: Mothers are using medicines during pregnancies; the extent varies across the world and is generally difficult to compare. In this registry-based study, we examined more than 100,000 Norwegian pregnancies and described the drug prescription pattern of both fathers and mothers around conception and during pregnancy (mothers).

What this study adds: In every trimester of pregnancy, about 30% of the mothers was dispensed a drug. The total drug exposure did not seem to diminish throughout pregnancy. One-quarter of the fathers was dispensed drugs during the last 3 months prior to conception.

Aims: The primary aim of this study was to describe the use of prescribed drugs in both mothers and fathers before and during pregnancy in Norway.

Methods: This population-based cohort study was based on data retrieved from the Medical Birth Registry of Norway and the Norwegian Prescription Database. These registries cover the entire population of Norway. Information on >100,000 births during 2004-2006 in the birth registry was linked to prescription data. Prescriptions issued to mothers just prior to, during and after the pregnancies as well as prescriptions to fathers just prior to conception were identified.

Results: Among mothers, 83% were prescribed drugs during the period 3 months prior to estimated conception until 3 months after giving birth. The mothers who received drugs were prescribed on average 3.3 different Anatomical Therapeutic Chemical (ATC) codes (range 1-38). During pregnancy, 57% were prescribed drugs. In the first trimester, 33% of mothers were dispensed drugs, while the figure was 29% for mothers in the last trimester. Among fathers, 25% used prescribed drugs during the 3 months prior to conception, with on average 1.9 different ATC codes (range 1-22).

Conclusion: Large proportions of both fathers and mothers were dispensed drugs prior to conception or during pregnancy. While there is a high awareness of the issues involved in maternal drug use in pregnancy, possible teratogenic effects of drug use in fathers shortly before conception should be further explored.

Figure 1

Percentage of mothers who had dispensed prescriptions 3 months prior to pregnancy to 3 months after pregnancy (based on n = 106 329 pregnancies). (All drugs, (▪); Excl. Contraceptives, (□))

Figure 2

Percentage of women who had dispensed prescriptions for three categories of drugs, defined by Bakker et al.[4], from 3 months prior to pregnancy to 3 months after pregnancy (based on n = 106 329 pregnancies). (Drugs for chronic conditions, (▪); Drugs for occasional and short-time use, (□); Pregnancy-related drugs, (•))