RISK OF CHROMOSOMAL-ABNORMALITIES, WITH EMPHASIS ON LIVE-BORN OFFSPRING OF YOUNG MOTHERS

In a large public urban hospital obstetrics service with >123,000 deli veries in a 10-year period (1980-89), the frequencies (0.12%) of any t ype of chromosomal abnormality and of trisomy syndromes were analyzed for maternal age-related risk, by logistic regression. Focusing on ver y young gravidas, we found that in the study period there were 9,332 b irths (7.5% of all deliveries) to mothers less than or equal to 16 yea rs old. Estimated risks of chromosomal abnormalities among offspring a ssociated with very young maternal age (9-16 years) were similar to th ose age-associated risks of mothers 20-29 years old. Risks of chromoso mal abnormalities increase with advancing maternal age and are indepen dent of ethnicity.