Reproductive outcome of couples with recurrent miscarriage and balanced chromosomal abnormalities

Despite known association of parental carriers of structural chromosomal rearrangements with a history of recurrent pregnancy loss (RPL), the possibility of having a miscarriage due to an unbalanced chromosomal aberration remains unknown. There has been limited research on the reproductive outcome of such couples. The present study was done to report the distribution of structural chromosome rearrangements in patients experiencing RPL and to describe subsequent pregnancy outcomes in the carriers.

Chromosomal analysis was performed on blood samples from 788 individuals with RPL and distribution of chromosomal anomalies was studied. In couples found to have chromosomal rearrangements, pregnancy outcomes were recorded over 2 years. In the subsequent pregnancy, cytogenetic analysis was done on amniotic fluid (obtained at 16-20 weeks), or on miscarriage specimens (in pregnancies that failed to continue).

Chromosomal rearrangements were identified in 6.8% (54/788) cases (including 5.9% reciprocal translocations, 0.7% Robertsonian translocations, and 0.1% inversions). The risk of having a chromosomal aberration was not related to the number of previous miscarriages. Over the next 2 years, two-thirds of the 49 documented pregnancies resulted in a normal live birth, and one-third miscarried. Most miscarriages (56.2%) were euploid, two were trisomic and 12.5% had an unbalanced translocation.

In couples with no other cause of RPL other than a structural chromosomal rearrangement, nearly two-thirds are likely to have a normal outcome in subsequent pregnancy. Couples with pure abortion histories carry higher risk for cytogenetic abnormality than couples with normal children in addition to abortions.