Association of age and parity with intrauterine device expulsion

To investigate whether age 14 to 19 years and nulliparity are associated with expulsion of levonorgestrel and copper intrauterine devices (IUDs).

This was a planned secondary analysis of the Contraceptive CHOICE Project. We used Kaplan-Meier survival analysis to estimate expulsion rates for the first levonorgestrel or copper IUD received during study participation. Cox proportional hazards regression models were used to investigate baseline characteristics associated with expulsion.

A total of 5,403 females were included; 4,219 (78%) used the levonorgestrel IUD and 1,184 (22%) used the copper IUD. There were 432 initial expulsions reported. The 36-month cumulative expulsion rate was 10.2 per 100 IUD users and did not vary by IUD type (levonorgestrel IUD 10.1 compared with copper IUD 10.7, P=.99). In the bivariate analysis, multiple characteristics including age, nulliparity, immediate postabortion insertion, and heavy menses were associated with expulsion. The cumulative rate of expulsion was lower in nulliparous women compared with parous women (8.4 compared with 11.4; P<.001) and higher in females aged 14 to 19 compared with older women (18.8 compared with 9.3; P<.001). After adjusting for confounders and stratifying by IUD type, the hazard ratio of expulsion for females aged 14 to 19 years was 2.26 (95% confidence interval [CI] 1.68-3.06) for the levonorgestrel IUD and 3.06 (95% CI 1.75-5.33) for the copper IUD. Compared to parous levonorgestrel IUD users, expulsion was lower for nulliparous levonorgestrel IUD users (adjusted hazard ratio 0.59, 95% CI 0.44-0.78).

IUD expulsions were not increased in nulliparous females. More expulsions were observed in females aged 14 to 19 compared with older women regardless of parity or IUD type.

: II.