Abstract
OBJECTIVES: This systematic review aimed to update a 2016 review and answer two questions: (1) Among breastfeeding women, does the use of progestogen-only contraception (POC) (ie, pills, injectables, implants, hormonal intrauterine devices) increase the risk of poor breastfeeding or infant outcomes compared with those not using POC? (2) Among breastfeeding women, does the initiation of POC before 6 weeks postpartum increase the risk of poor breastfeeding or infant outcomes compared with the initiation of POC at 6 weeks or later? METHODS: We searched multiple databases (MEDLINE, EMBASE, Cochrane, ClinicalTrials.gov and CINAHL) from inception to 6 September 2023. We extracted data and assessed risk of bias (RoB) for each study and certainty of evidence for each outcome. RESULTS: Sixty-one articles met the inclusion criteria; 11 were newly identified since the previous review, most with high RoB. Nine new randomised and non-randomised studies assessing breastfeeding and/or infant outcomes met the inclusion criteria for Question 1. Two new randomised studies assessing breastfeeding and/or infant outcomes met the inclusion criteria for Question 2, examining early versus late initiation of the implant. One new article for each objective included preterm infants. For both questions, studies continue to find no significant adverse effects on breastfeeding (eg, continuation, supplementation, duration) or infant (eg, growth, illness) outcomes. The certainty of evidence ranged from very low to moderate across outcomes. CONCLUSIONS: This updated systematic review provides additional evidence for the safety of POC use during breastfeeding. Newly identified studies are consistent with the prior review in suggesting no consistent findings of adverse effects, while adding evidence for preterm infants.