Objective: To determine the range and prevalence of chromosomal abnormalities occurring in failing pregnancies in subfertile women.
Design: Prospective biochemical and ultrasound monitoring of all pregnancies conceived between 1988 and 1990 in a subfertile population.
Setting: A single-centre specialist fertility clinic in Perth, Western Australia.
Subjects: Tissue from 50 early pregnancy losses was successfully cultured for chromosomal analysis from 46 pregnancies comprising 29 anembryonic pregnancies, 9 miscarriages and 8 ectopic pregnancies.
Main outcome measures: Impending pregnancy loss was identified at an early stage. Chromosomal analysis was performed on chorionic villi obtained before the diagnosis became clinically evident.
Results: Significant chromosomal abnormalities were identified in 54% (14/26) of early pregnancy losses where gamete manipulation was involved and 45% (9/20) of those following spontaneous conception. The most common abnormalities were trisomies (12 pregnancies, mainly trisomy 16), triploidies (3 pregnancies) and monosomy X (3 pregnancies). An excess of female fetuses was noted with only 24% of conceptuses (11/46) bearing a Y chromosome.
Conclusions: The data indicate a similar rate of chromosomal abnormalities underlying pregnancy losses at earlier stages of pregnancy and after infertility treatments as that reported from the general population. Gamete manipulation does not appear to confer a higher rate of chromosomal abnormalities in ensuing pregnancies.