Cytogenetic and histologic analyses of spontaneous abortions.

In a study of spontaneous abortions the correlations between karyotype (166 cases), anamnestic data, and macroscopic and histologic findings in placentas (107 cases) and embryos (73 cases) were analyzed. The main results were: 1. The rate of chromosomal aberrations was 39%. Trisomies predominated (60%), followed by monosomy X (20%), triploidies (14%), and structural aberrations (6%). 2. In trisomies a clear prevalence of female sex constitution (2:1) was observed. In normal karyotypes a slight prevalence of females was seen (1.2:1). 3. With increasing maternal age, more trisomies were found in the abortions. 4. Women whose index abortion had a normal karyotype had a history of fewer births but more abortions. 5. Trisomies of acrocentric chromosomes were mainly chorionic sacs with an embryo, while trisomies of the other autosomes resulted in intact empty sacs. 6. The average developmental stage of the embryos was 5 weeks, with a mean gestational age of 14 weeks. Gross malformations were found in 58% of the embryos.