Study: Ectopic pregnancy risk increases with lower-dose IUDs
Lower-dose IUDs were associated with an increased risk for ectopic pregnancy compared with higher-dose systems, according to a retrospective cohort study published in Obstetrics & Gynecology.
Overall, however, the levonorgestrel-releasing intrauterine systems (LNG-IUS) of 13.5 mg, 19.5 mg and 52 mg doses recorded low absolute risks for ectopic pregnancy, demonstrating their protective effects, according to the study.
“Study populations of previous studies of LNG-IUS 13.5 mg and 19.5 mg have excluded women with known risk factors for ectopic pregnancy,” Karin Elgemark, MD, a PhD student at the Karolinska Institute in Stockholm, Sweden, and colleagues wrote. “In the current analysis, we included all women and all cases with an ectopic pregnancy diagnosed for a period of 72 months, minimizing selection bias and contributing to external validity.”
Elgemark and colleagues examined electronic medical records from Stockholm County, Sweden, from Jan. 1, 2014, to Dec. 31, 2019, of 2,224 women with an ectopic pregnancy diagnosis to assess the risk of ectopic pregnancy when using LNG-IUS at the three different doses.
At fertilization, 105 women had a hormonal IUD in situ, 94 of whom had a known date of insertion after Jan. 1, 2014, and were included in the Pearl Index analysis. This total included 59 women with LNG-IUS 13.5 mg, 11 women with LNG-IUS 19.5 mg and 24 women with LNG-IUS 52 mg.
In the first year of use, 31 women in the LNG-IUS 13.5 mg group (53%), seven in the LNG-IUS 19.5 mg group (64%) and six in the LNG-IUS 52 mg group (25%) were diagnosed with ectopic pregnancy.
In the total study period, the estimated Pearl indices were 0.136 (95% CI, 0.106-0.176) for the LNG-IUS 13.5 mg, 0.037 (95% CI, 0.021-0.067) for the LNG-IUS 19.5 mg and 0.009 (95% CI, 0.006-0.014) for the LNG-IUS 52 mg.
LNG-IUS 13.5 mg was associated with a higher risk for ectopic pregnancy in the first year of use and the highest incidence rate over the total study period.
“These findings highlight the importance of exploring risk factors for ectopic pregnancy to guide the woman’s choice when opting for a hormonal IUD, recommending a higher-dose LNG-IUS to women with risk factors for ectopic pregnancy,” Elgemark and colleagues wrote.