Postpartum contraception method type and risk of a short interpregnancy interval in a state Medicaid population.

Objective: To evaluate the likelihood of a short interpregnancy interval (IPI) resulting in a birth among women covered by Medicaid, as a function of postpartum contraceptive method type.

Study Design: We used Medicaid claims and eligibility data to identify women (aged 15-44) who had a Medicaid-financed birth in Delaware in the years 2012-2014 (n = 10,328). Claims were analyzed to determine postpartum contraceptive type within 60 days of the index birth, and linked birth certificates were used to determine the incidence and timing of a subsequent birth through 2018 (regardless of payer). We used logistic regression to analyze the likelihood of having a short IPI following the index birth as a function of postpartum contraceptive type, controlling for preterm births, parity, having a postpartum checkup, and maternal characteristics including age, race, education, and marital status.

Results: Compared to patients receiving postpartum long-acting reversible contraceptive methods (LARC), patients with no contraceptive claims had nearly 5 times higher odds (odds ratio [OR] = 4.98, confidence interval [CI] = 3.05-8.13) and those with claims for moderately effective methods (injectable, pill, patch, or ring) had 3.5 times higher odds (OR = 3.51, CI = 2.13-5.77) of a subsequent birth following a short IPI.

Conclusions: In a state population of Medicaid-enrolled women, women with claims for postpartum LARC had substantially lower risk of a short IPI resulting in a birth.

Implications: Women who received LARC within 60 days postpartum are less likely to experience a short interpregnancy interval resulting in a birth. The evidence suggests that recent state policy changes that make postpartum LARC more accessible to those that desire it will be an effective strategy in helping patients obtain desired birth intervals.