Concurrent use of hormonal long-acting reversible contraception by women of reproductive age dispensed teratogenic medications, Australia, 2013–2021: a retrospective cohort study

Objectives: To examine patterns in the dispensing of category X medications (Therapeutic Goods Administration categorisation system for prescribing medicines in pregnancy) to women aged 15–49 years in Australia during 2008–2021, and patterns of concurrent use of hormonal long-acting reversible contraception (LARC) and other hormonal contraception. Study design: Retrospective cohort study; analysis of 10% random sample of national Pharmaceutical Benefits Scheme dispensing data. Participants, setting: Women aged 15–49 years dispensed category X medications, Australia, 1 January 2013 – 31 December 2021. Main outcome measures: Incident and prevalent dispensing of category X medications, by medication class, age group, and year; contraceptive overlap (proportions of women dispensed hormonal LARC or other hormonal contraception that overlapped the first dispensing of category X medications), by medication class. Results: Among 15 627 women aged 15–49 years dispensed category X medications during 2013–2021, the prevalence of dispensing increased from 4.6 in 2013 to 8.7 per 1000 women aged 15–49 years in 2021; the largest increase was for the dispensing of dermatological agents, from 3.9 to 7.9 per 1000 women aged 15–49 years. LARC overlap was inferred for 2059 women at the time of first dispensing of category X medications (13.2%); 3441 had been dispensed any type of hormonal contraception (22.1%). The proportion with LARC overlap was smallest for those dispensed dermatological agents (1806 of 14 331 women, 12.6%); for this drug class, both LARC overlap (adjusted odds ratio [aOR], 0.17; 95% confidence interval [CI], 0.14–0.20) and any hormonal contraception overlap (aOR, 0.28; 95% CI, 0.25–0.32) were less likely for those aged 15–19 years than for women aged 25–29 years. Conclusions: Concurrent use of highly effective hormonal contraception at the time of first dispensing of category X medications is low in Australia, raising concerns about potential fetal harms during unintended pregnancies. Awareness of the importance of hormonal contraception and its uptake by women prescribed category X medications should be increased.