The Correlation Between Maternal Age and Fetal Sex Chromosome Aneuploidies: A 8-Year Single Institution Experience in China

Abstract

Background: To date, it has been widely accepted that the risk of autosomal aneuploidies (including T21, T18 and T13) is directly related to the increase in maternal age. However, up to now, the relationship between maternal age and fetal sex chromosome aneuploidies (SCAs) was still unclear. This study aimed to investigate maternal age-specific rates for common SCAs (including 45,X, 47,XXY, 47,XXX and 47,XYY) in fetuses. Methods: We retrospectively investigated a 8-year experience of prenatal diagnosis for fetal chromosome aberrations by second-trimester amniocentesis at a university teaching hospital in China. 20,409 amniotic fluid specimens collected at 19–22+6 gestational weeks were included in this study. Conventional cytogenetic analysis was performed on all samples. Maternal age was as the only indication for the statistical analysis. The women were categorized into five age groups (≤23, 24-28, 29-33, 34-38, ≥39 years) based on maternal age at the time of amniocentesis and entered as a categorical variable in all samples. The correlation between fetal SCAs and maternal age was determined using the logistic regression analysis. A chi-square test was performed to compare the incidence of fetal SCAs among age groups. Results: A total of 179 cases of fetal SCAs were detected, and the incidence was 8.77‰ (about 1/114), far higher than the earlier publication of 1/500. The incidence of all SCAs increased significantly with advancing maternal age (SE, 0.014; odds ratio, 1.044; P=0.002), from 5.81 per 1,000 fetuses at the 24-28 years to 10.92 per 1,000 at the ≥39 years. The incidence of all SCAs was also significantly different among age groups (χ2=10.197, P=0.037<0.05). Specifically, the incidence of 45,X (SE, 0.037; odds ratio, 0.916; P=0.017) and 47,XXY (SE, 0.024; odds ratio, 1.127; P=0.000) had significant correlation with maternal age, while the incidence of 47,XXX and 47,XYY had no correlation with maternal age (P=0.473; P=0.272, respectively). Conclusions: Maternal age was ascertained to be a strong risk factor for fetal SCAs. The incidence of 45,X and 47,XXY was significantly correlated with maternal age, while the incidence of 47,XXX and 47,XYY was not.

Pregnancy at Age 35 Years or Older

“…Sex chromosome trisomies, specifically 47, XXX and 47, XXY increase with increasing maternal age. In contrast, sex chromosome monosomy (ie, 45, X) does not appear to be affected by maternal age (39,40). Likewise, copy number variants are independent of maternal age at pregnancy (41).…”