The correlation between maternal age and fetal sex chromosome aneuploidies: a 8-year single institution experience in China

BACKGROUND: Although a few studies have investigated a possible association between maternal age and fetal sex chromosome aneuploidies (SCAs), most of these studies were limited to advanced maternal age (AMA) women and the results were conflicting. This study aimed to investigate the correlation between maternal age and common fetal SCAs (including 45,X, 47,XXY, 47,XXX and 47,XYY) in pregnant women of different ages that not only limited to AMA women. 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. 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). The incidence of fetal SCAs increased significantly with advancing maternal age (SE, 0.014; odds ratio, 1.044; P = 0.002). 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). The incidence of fetal SCAs was also significantly different among age groups (χ(2) = 10.197, P = 0.037 < 0.05), from 5.81 per 1000 fetuses at the 24–28 years to 10.92 per 1000 at the 39(+) years. CONCLUSIONS: Maternal age was ascertained to be a strong risk factor for fetal SCAs.