Reproductive outcomes in patients with recurrent pregnancy loss associated with a structural chromosome abnormality

Abstract

Objectives: Recurrent pregnancy loss (RPL), defined as two or more pregnancy losses, affects up to 5% of couples trying to establish a family. A structural chromosome abnormality is found in association with RPL in 3.5% of couples (Stephenson, 1996). The objectives of this study are: 1)to summarize the reproductive outcomes of RPL couples with an identified structural chromosome abnormality.2)to describe the cytogenetic findings of pregnancy losses in this cohort.3)to compare these results to published controls.Study Design: This study is a retrospective cohort-control study.Methods and Materials: Couples were identified using the BC Women’s RPL Database (ACCESS 2000) created by one of the authors (MDS). Inclusion criteria were: 1) a history of at least 2 miscarriages <20 weeks of gestation; and 2) either the maternal or paternal partner was identified as a carrier of a balanced structural chromosome abnormality. Descriptive analyses were done using EpiInfo (CDC, 2002).Results: 34 couples with 183 pregnancies were identified. Mean maternal age at the time of pregnancy loss or delivery was 30 years (SD 5). The distribution of the structural chromosome abnormalities in the RPL carriers is shown below.Of these 183 pregnancies, 102 (56%) resulted in miscarriage under 10 weeks’ gestation, and 27 (15%) resulted in an intrauterine fetal demise of 10 or more gestational weeks. Four of the pregnancies were terminated electively. The remaining 50 pregnancies resulted in livebirths (27%). An amniocentesis was performed in 9 of these 50 pregnancies; the results were diploid (46, XX or 46, XY) in 4 of the 9 pregnancies; the other 5 consisted of a balanced structural chromosome abnormality similar to the parental carrier.34 of the 129 (26%) pregnancy losses were sent for cytogenetic analysis; 9 did not grow in culture for a failure rate of 26%. The cytogenetic findings and comparisons to historic controls are shown below. Tabled 1 Tabled 1Conclusions: RPL couples who have a structural chromosome abnormality have a high risk of pregnancy loss (70%), of which approximately one-third can be attributed to an unbalanced translocation or inversion. This incidence is higher than that seen in published controls (4–6%). Since 44% of the pregnancy losses are not due to a structural or numeric chromosome abnormality, other factors associated with RPL should be evaluated. Ongoing pregnancies appear to be at low risk of having an unbalanced structural chromosome abnormality in carriers of a balanced structural chromosome abnormality ascertained by a history of RPL. Objectives: Recurrent pregnancy loss (RPL), defined as two or more pregnancy losses, affects up to 5% of couples trying to establish a family. A structural chromosome abnormality is found in association with RPL in 3.5% of couples (Stephenson, 1996). The objectives of this study are: 1)to summarize the reproductive outcomes of RPL couples with an identified structural chromosome abnormality.2)to describe the cytogenetic findings of pregnancy losses in this cohort.3)to compare these results to published controls. Study Design: This study is a retrospective cohort-control study. Methods and Materials: Couples were identified using the BC Women’s RPL Database (ACCESS 2000) created by one of the authors (MDS). Inclusion criteria were: 1) a history of at least 2 miscarriages <20 weeks of gestation; and 2) either the maternal or paternal partner was identified as a carrier of a balanced structural chromosome abnormality. Descriptive analyses were done using EpiInfo (CDC, 2002). Results: 34 couples with 183 pregnancies were identified. Mean maternal age at the time of pregnancy loss or delivery was 30 years (SD 5). The distribution of the structural chromosome abnormalities in the RPL carriers is shown below. Of these 183 pregnancies, 102 (56%) resulted in miscarriage under 10 weeks’ gestation, and 27 (15%) resulted in an intrauterine fetal demise of 10 or more gestational weeks. Four of the pregnancies were terminated electively. The remaining 50 pregnancies resulted in livebirths (27%). An amniocentesis was performed in 9 of these 50 pregnancies; the results were diploid (46, XX or 46, XY) in 4 of the 9 pregnancies; the other 5 consisted of a balanced structural chromosome abnormality similar to the parental carrier. 34 of the 129 (26%) pregnancy losses were sent for cytogenetic analysis; 9 did not grow in culture for a failure rate of 26%. The cytogenetic findings and comparisons to historic controls are shown below. Tabled 1 Tabled 1 Conclusions: RPL couples who have a structural chromosome abnormality have a high risk of pregnancy loss (70%), of which approximately one-third can be attributed to an unbalanced translocation or inversion. This incidence is higher than that seen in published controls (4–6%). Since 44% of the pregnancy losses are not due to a structural or numeric chromosome abnormality, other factors associated with RPL should be evaluated. Ongoing pregnancies appear to be at low risk of having an unbalanced structural chromosome abnormality in carriers of a balanced structural chromosome abnormality ascertained by a history of RPL.