Postpartum hormonal contraceptive use in Denmark during 1997-2021

Introduction: Hormonal contraception is used by over a quarter of a billion worldwide. In Denmark, 84% have used it before their first pregnancy. After pregnancy, mothers are routinely advised to consider contraception to avoid short interpregnancy intervals due to perinatal and maternal health risks. Yet, mothers are not recommended to start combined hormonal contraception within six weeks postpartum due to an increased thromboembolic risk. This study provides an overview of postpartum hormonal contraceptive use in Denmark. Material and methods: This descriptive study is based on Danish national health registries on mothers who delivered during 1997-2021. The cumulative incidence of HC initiation one year after delivery is reported by calendar year and age group. Timing of initiation is reported as the median time from delivery. Hormonal contraception was categorized according to hormone type and method of administration. Results: A total of 676 759 first-time and 552 142 second-time mothers were registered, with a cumulative incidence of hormonal contraceptive initiation of 41.0% (95% CI, 40.9-41.1) and 40.5% (95% CI, 40.4-40.6), respectively. From 1997 to 2021, the cumulative incidence of first-time mothers who initially used progestogen-only pills increased from 3.8% (95% CI, 3.5-4.0) to 14.4% (95% CI, 13.9-14.8) and intrauterine levonorgestrel-releasing systems from 0.1% (95% CI, 0.1-0.2) to 12.6% (95% CI, 12.3-13.0). In contrast, combined oral contraception initiation decreased from 31.3% (95% CI, 30.7-31.8) to 7.8% (95% CI, 7.5-8.2). Among first-time mothers initiating hormonal contraception, the median time of initiation decreased from 4.7 (Q1-Q3, 2.5-7.5) months during 1997-2001 to 2.5 (Q1-Q3, 2-0-4.0) months during 2017-2021. The cumulative incidence of first-time mothers using combined hormonal contraception six weeks after delivery decreased from 1.5% (95% CI, 1.5-1.6) during 2007-2011 to 0.5% (95% CI, 0.5-0.5) during 2017-2021. Conclusions: Within the first year after childbirth, 41% of first- and second-time mothers initiated hormonal contraception in Denmark during 1997-2021. Throughout 1997-2021, mothers started earlier after delivery and more often used progestogen-only contraception. Few started combined hormonal contraception within 6 weeks after delivery in accordance with national guidelines. Taken together, the pattern of HC use over time reflects a change to safer contraceptive methods postpartum which minimizes thromboembolic risk.