Down syndrome and maternal age: changes over time and review of risk factors

During 1987-1996, 292 Egyptian Down syndrome (Trisomy 21) infants were identified in Human Genetics Department in Alexandria. They comprised 139 males and 153 females (sex ratio 0.91). Data on maternal age, paternal age and birth order were analyzed. Maternal ages were examined for transient changes over time and for linear trends. Significant changes in maternal age over the 10 years period of study were observed. First born infants were at greater risk of trisomy 21 than higher order of births, independent of maternal age.