Effect of adenomyosis on adverse obstetrical outcomes in twin pregnancies achieved with assisted reproductive technology.

The incidence of twin pregnancy with adenomyosis (AD) is increasing due to advanced maternal age and infertility treatment. We retrospectively analysed the data of 45 dichorionic twin pregnancies complicated with AD in contrast to a control group of dichorionic twin pregnancies without AD (n = 130). Compared with those in the control group, the AD group had a higher overall foetal loss rate (8.9% vs. 0.8%; adjusted p = .031; odds ratio (OR), 13.6; 95% confidence interval (CI), 1.27-146.3), higher early preterm delivery rate (20% vs. 6.9%; adjusted p = .007; OR, 4.22; 95% CI, 1.47-12.13) and higher rate of hypertensive disorders of pregnancy (26.7% vs. 7.7%; adjusted p = .005; OR, 3.94; 95% CI, 1.5-10.2). Patients in the AD group were significantly more likely to require transfusion during or after delivery (17.8% vs. 5.4%; p = .026) and have smaller babies (2168 g vs. 2399 g; p = .004) compared with those in the control group. This is the first study to report that twin pregnancies with AD may be treated as high-risk for placental dysfunction and may need closer monitoring during pregnancy.Impact StatementWhat is already known on this subject? The incidence of twin pregnancy with adenomyosis (AD) is increasing due to advanced maternal age and infertility treatment. However, there are very few studies on the effect of AD on pregnancy outcomes.What the results of this study add? This is the first study to report that twin pregnancies with AD have higher rates of early preterm delivery, hypertensive disorders of pregnancy, and transfusion compared to controls.What the implications are of these findings for clinical practice and/or further research? The results of this study can be used in counselling twin pregnancies with AD. Further research is needed to confirm the current findings.