Trisomic pregnancy and earlier age at menopause

We tested the hypothesis that the connection between advanced maternal age and autosomal trisomy reflects the diminution of the oocyte pool with age. Because menopause occurs when the number of oocytes falls below some thresh old, our hypothesis is that menopause occurs at an earlier age among women with trisomic pregnancies than it does among women with chromosomally norma l pregnancies. To determine their menstrual status, we interviewed women fr om our previous study of karyotyped spontaneous abortions who, in 1993, wer e age greater than or equal to 44 years. Pre-menopausal women completed int erviews every 4-5 mo, until menopause or until the study ended in 1997. The primary analyses compare 111 women whose index pregnancy was a trisomic sp ontaneous abortion with two groups: women whose index pregnancy was a chrom osomally normal loss (n = 157) and women whose index pregnancy was a chromo somally normal birth (n = 226). We used a parametric logistic survival anal ysis to compare median ages at menopause. The estimated median age at menop ause was 0.96 years earlier (95% confidence interval -0.18 to 2.10) among w omen with trisomic losses than it was among women with chromosomally normal losses and chromosomally normal births combined. Results were unaltered by adjustment for education, ethnicity, and cigarette smoking. Our results su pport the hypothesis that trisomy risk is increased with decreased numbers of oocytes. Decreased numbers may indicate accelerated oocyte atresia or fe wer oocytes formed during fetal development.