Lactation status and the risk of early TCu-380A intrauterine device (IUD) expulsion in women in Mexico

Background: IUD expulsion complicates 2.6-24% of insertions. Expulsions often occur within one month after insertion. Other risks include younger age, nulliparity, increased menstrual flow, severe dysmenorrhea, and immediate postpartum placement. Approximately 20% of expulsions go undetected, increasing the risk of unintended pregnancy. This study was designed to calculate the odds of early Cu-380A IUD expulsion by lactation status, adjusting for measured confounders and interaction terms.

Methods: Using data from a prospective study of 969 parous women who had a TCu-380A inserted in/near Mexico City and returned one month later, a logistic regression model was created comparing the odds of expulsion in women breastfeeding or not at one month. Interaction terms for lactation-menstrual status at insertion and lactation-bleeding complaints at follow-up were assessed for significance using likelihood ratio tests. Using backwards elimination, demographic and reproductive factors were deemed confounders if removing them changed the fully-adjusted odds ratios by >10%.

Results: Among women cycling within 5 weeks of insertion who reported bleeding complaints at follow-up, the OR of IUD expulsion was 16.49 (95% CI:2.52, 108.12) for breastfeeding versus non-breastfeeding women, adjusted for age, history of abortion, ease of insertion, and parity. Other ORs: among women amenorrheic at insertion with bleeding complaints, 3.03 (95% CI: 0.32, 28.88), among cycling women without bleeding complaints, 2.35 (95% CI: 0.64, 8.61), and among amenorrheic women without bleeding complaints, 0.43 (95% CI: 0.08, 2.42).

Conclusions: TCu-380A IUD insertion in breastfeeding women while still amenorrheic may decrease the frequency of early expulsion.