Progestin-only pills and intrauterine devices do not increase the risk for venous thromboembolic events, according to a meta-analysis in BMJ. However, an association between injectable progestin and VTE could not be ruled out.
The meta-analysis included three retrospective cohort studies and five case-control studies comparing progestin-only contraception use with no hormone use. Overall, progestin-only methods were not associated with VTE risk — a finding that held true in subanalyses of progestin-only pills and IUDs. Use of injectable progestin was associated with a doubling of risk, although only two studies evaluated this formulation.
The authors call for more research into the potential increase in risk with injectable progestin. “In the interim,” they conclude, “we suggest consideration of non-injectable forms of progestin-only contraception for highest risk women.”