RECURRENCE RISK OF A SERIOUS, NONINHERITED CHROMOSOMAL ABNORMALITY

Objective: To investigate the recurrence risk of a serious, noninherit ed chromosomal abnormality. Design: Prospective and retrospective anal ysis. Setting: University-based prenatal diagnosis clinic. Patient(s): Data on 240 pregnancies in 165 couples after a pregnancy with a serio us chromosomal abnormality. Result(s): Autosomic trisomic pregnancy ha d occurred in 133 families. In these families, there were 193 new preg nancies, 132 in women under 35 years and 61 in women over 35 years. Th e recurrence rate was 2.3% in tile women under 35 years and 8.2% in th e women over 35 years, Pregnancy had occurred in 18 families with a se x-chromosomal abnormality. In these families, there were 24 new pregna ncies, 21 in women under 35 years and 3 in women over 35 years. All pr egnancies were chromosomally normal. Some other serious chromosomal ab normality had occurred in 14 families. In these families, there were 2 3 new pregnancies. Chromosomal abnormality recurred in two families: i n a woman under 35 years and in a woman over 35 years. Conclusion(s): The high recurrence rate of chromosomal abnormalities even in women un der 35 years warrants fetal chromosomal investigation in new pregnanci es. (C) 1997 by American Society for Reproductive Medicine.