Baseline Characteristics
In total, 1070 twin pregnancies were recruited in this study, 138 were excluded for final analysis. Among them, 91 subjects were lost to follow-up and 47 were diagnosed with Twin to twin transfusion syndrome (TTTs) and underwent a medical intervention. Finally, we obtained the completed information from 932 pregnancies (277 in the LDA group, 655 in the control group). (Figure 1) Before the PSM, the baseline characteristics vary widely. Ages of mothers in the LDA group (29.55y) were younger than that in the control group (30.22y, p =0.022). In the LDA group, the percentage of spontaneous conception was 65.3%, which was higher than the control group (36.9%,p <0.001). Chorionicity subtypes were also quite different between the two groups (p <0.001). These data were shown in Table.1.
After PSM, 235 women who received LDA treatment and 235 who did not use LDA were finally paired for analysis. The characteristics were matched well (all p >0.05 & all SMD<0.1). These data were shown in Table.2.