3.1 UVMR analyses of risk factors on medical abortion
We selected 45, 207, 136, 34, 85, 154, 60, 55 and 6 SNPs as genetic instruments meting genome-wide statistical significance for HI, EA, CP, AC, SB, AFS, LNSP, AFB and ALB after LD clumping, respectively. The mean F-statistics for risk factors ranged from 38.28 to 77.30 (see Supplementary table 1).
Primary IVW method showed that genetic variants associated with increased HI, EA, AFS, and AFB, were negatively causally related to the risk of medical abortion(HI, OR=0.569, 95% CI, 0.463–0.699, P =7.93E-08; EA, OR=0.875, 95% CI, 0.851–0.900, P=6.02E-21; AFS, OR=0.439, 95% CI, 0.376–0.513, P=5.17E-25; AFB, OR=0.815, 95% CI, 0.769-0.864, P=5.46E-12). Adversely, SB and LNSP were risk factors for medical abortion (SB, OR=1.424, 95% CI, 1.280-1.584, P =8.32E-11; LNSP, OR=2.777, 95% CI, 2.059-3.745, P=2.14E-11). We found no evidence for the causal effect of AC and ALB on the risk of MA(AC, OR=1.297, 95% CI, 0.980-1.716, P=6.92E-02; ALB, OR=0.659, 95% CI, 0.408-1.063, P=8.75E-02). The causal connection between CP and MA was in doubt, as the causal estimates were directionally inconsistent(see Figure 2).