Trends in Timing of Prenatal Diagnosis and Abortion for Fetal Chromosomal Abnormalities

Objective: Our objective was to evaluate changes in the timing of prenatal diagnosis and abortion for chromosomal abnormalities over the past 10 years.

Study Design: This retrospective review identified singleton pregnancies with fetal chromosomal abnormalities that were diagnosed from 2005-2014 and included Down syndrome, Trisomy 18, and Trisomy 13. The study period was divided into 3 intervals: 2005-2006; 2007-2011; and 2012-2014. Gestational ages at prenatal diagnosis and abortion were compared over these intervals.

Results: The 213 cases included 142 cases of Down syndrome (66.7%), 47 cases of Trisomy 18 (22.1%), and 24 cases of Trisomy 13 (11.3%). Two hundred one women (94.4%) chose to undergo abortion. The median gestational ages at prenatal diagnosis and abortion for Trisomy 18 or 13 were 12 weeks (interquartile range, 12-13 weeks) and 13 weeks (interquartile range, 12-15.5 weeks) and did not change over the study period. In contrast, in pregnancies with Down syndrome, the median gestational age at prenatal diagnosis (16, 13, and 12 weeks; P < .001) and abortion (17, 14, and 13 weeks; P < .001) both decreased significantly over the study intervals. In Down syndrome pregnancies, the proportion of women who underwent chorionic villus sampling significantly increased over the 3 study intervals (36%, 63%, and 86%; P < .001).

Conclusion: Since 2005, the gestational ages at prenatal diagnosis and abortion for Down syndrome have declined significantly. These changes are likely attributable to improvements in early screening that leads to higher rates of chorionic villus sampling.