Objective The primary objective of this study was to test the effectiveness of integrating family planning service components into infant immunization services to increase modern contraceptive method use among postpartum women.

Methods The study was a separate sample, parallel, cluster-randomized controlled trial. Fourteen randomly selected primary health facilities were equally allocated to intervention (integrated family planning and immunization services at the same time and location) and control groups (standard immunization services only). At baseline (May–June 2010), we interviewed postpartum women attending immunization services for their infant aged 6 to 12 months using a structured questionnaire. A separate sample of postpartum women was interviewed 16 months later after implementation of the experimental health service intervention. We used linear mixed regression models to test the study hypothesis that postpartum women attending immunization services for their infants aged 6–12 months in the intervention facilities will be more likely to use a modern contraceptive method than postpartum women attending immunization services for their infants aged 6–12 months in control group facilities.

Results We interviewed and analyzed data for 825 women from the intervention group and 829 women from the control group. Results showed the intervention had a statistically significant, positive effect on modern contraceptive method use among intervention group participants compared with control group participants (regression coefficient, 0.15; 90% confidence interval [CI], 0.04 to 0.26). Although we conducted a 1-sided significance test, this effect was also significant at the 2-sided test with alpha = .05. Among those women who did not initiate a contraceptive method, awaiting the return of menses was the most common reason cited for non-use of a method. Women in both study groups overwhelmingly supported the concept of integrating family planning service components into infant immunization services (97.9% in each group), and service data collected during the intervention period did not indicate that the intervention had any negative effect on infant immunization service uptake.

Conclusion Integrating family planning service components into infant immunization services can be an acceptable and effective strategy to increase contraceptive use among postpartum women. Additional research is needed to examine the extent to which this integration strategy can be replicated in other health care settings. Future research should also explore persistent misconceptions regarding the relationship between return of menses and return to fertility during the postpartum period.