2.4.1 UVMR and MVMR analyses
For UVMR, we used inverse variance weighted MR (IVW MR) along with the complementary methods: simple mode, MR–Egger, weighted mode and weighted median to assess the evidence of the causal effects of each factor on MA, in order to detect the sensitivity of the results to different patterns of violations of IV assumptions, as consistency of results across methods strengthens an inference of causality[17].
For our MVMR analyses, combining EA along with HI, and risky behaviors along with HI or EA, and reproductive factors (AFS, LNSP) along with HI or EA, we used the multivariable inverse-variance weighted (IVW) method as the primary method to estimate the causal associations since it possesses the highest statistical power. The multivariable MR-Egger method was adopted as a complementary method to strengthen the main results.