Factors affecting parental decisions to terminate pregnancy in the presence of chromosome abnormalities: a Japanese multicenter study

Objective: To investigate the rates of termination of pregnancy (TOP) for fetal chromosomal abnormalities and factors related to such parental decision in Japan. Methods: A multicenter retrospective cohort study of chromosomal abnormalities diagnosed before 22 weeks of gestation between April 2008 and March 2015. The pregnancy outcomes and parental decisions were investigated. Results: Among 931 fetuses with chromosome abnormalities, the total TOP rate was 75.1% (699/931). TOP rates were 89.3% (585/655) in autosomal aneuploidies and 40.8% (51/125) in sex chromosome aneuploidies. Trisomy 21 showed the highest TOP rate (93.8% [390/416]) followed by trisomy 18 (84.5% [163/193]) and trisomy 13 (71.9% [23/32]). Indications for karyotyping were related to a parental decision for TOP (p < 0.01): in cases of autosomal aneuploidy, with fetal abnormal ultrasound findings as the reference value, diagnoses made following positive results at non-invasive prenatal testing (adjusted odds ratio [OR]: 13.7, 95% confidence interval [CI] 4.07–45.9) and those because of advanced maternal age (adj. OR 2.91, 95% CI 1.15–7.35) were significantly more frequent. Conclusions: In Japan, pregnancies with fetal trisomy 21 are more likely to result in TOP when diagnosed in utero than any other chromosome anomaly. The indications for prenatal karyotyping strongly affect the decision to TOP.