Prevalence of chromosomal mosaicism in pregnancies from couples with infertility

Objective: To determine if mosaicism that occurs in infertility and assisted reproductive technologies continues in the late first trimester and if this is unique to infertility or occurs in all pregnancies. Design: Retrospective case-controlled study. Setting: University hospital. Patient(s): 5337 consecutive chorionic villus samplings (CVS). Intervention(s): None. Result(s): We confirmed 69 mosaic karyotypes, a rate of 1.29%. Comparing spontaneous pregnancies with pregnancies from infertility treatment, no difference was found in the prevalence of mosaicism: 1.22% versus 1.32%, respectively. Subgroup analysis of infertile couples, comparing in vitro (assisted reproduction) with in vivo fertilization (other treatments) revealed a mosaicism rate of 1.84% and 0.41%, respectively. Confined placental mosaic (CPM) rates for infertility treated pregnancies and spontaneously conceived pregnancies were 0.88% and 0.92%, respectively. Subgroup analysis of infertile patients revealed a CPM rate of 1.15% for in vitro fertilization treatment and 0.41% for in vivo fertilization treatment. These results were not statistically significant. Conclusion(s): There was no difference in the prevalence of mosaicism at. the end of the first trimester in pregnancies conceived spontaneously compared with those with infertility. There was no difference in the prevalence of mosaicism when in vitro and in vivo treatment were compared. (Fertil Steril (R) 2009;91:2355-60. (C) 2009 by American Society for Reproductive Medicine.)