This nationwide population-based study conducted in Estonia documented very low effective contraceptive coverage during isotretinoin treatment among women of reproductive age.

We also documented a very low risk of unintended pregnancies in the group of women on isotretinoin and partially or not covered by contraception, perhaps due to abstinence, a contraceptive choice that has not yet been quantified in this population.

A multinational evaluation of pregnancy prevention programmes is needed to detect the underlying factors contributing to the wide disparities in contraceptive coverage.

Policymakers and public health professionals can use these risk factors to address weaknesses in prevention programme policy or implementation, or both, to reduce the number of potentially exposed pregnancies.