OBJECTIVE: To investigate the recurrence risk of a serious, noninherited chromosomal abnormality. DESIGN: Prospective and retrospective analysis. SETTING: University-based prenatal diagnosis clinic. PATIENT(S): Data on 240 pregnancies in 165 couples after a pregnancy with a serious chromosomal abnormality. RESULT(S): Autosomic trisomic pregnancy had occurred in 133 families. In these families, there were 193 new pregnancies 132 in women under 35 years and 61 in women over 35 years. The recurrence rate was 2.3% in the women under 35 years and 8.2% in the women over 35 years. Pregnancy had occurred in 18 families with a sex-chromosomal abnormality. In these families, there were 24 new pregnancies, 21 in women under 35 years and 3 in women over 35 years. All pregnancies were chromosomally normal. Some other serious chromosomal abnormality had occurred in 14 families. In these families, there were 23 new pregnancies. Chromosomal abnormality recurred in two families: in a woman under 35 years and in a woman over 35 years. CONCLUSION(S): The high recurrence rate of chromosomal abnormalities even in women under 35 years warrants fetal chromosomal investigation in new pregnancies.
OBJECTIVE: To investigate the recurrence risk of a serious, noninherited chromosomal abnormality. DESIGN: Prospective and retrospective analysis. SETTING: University-based prenatal diagnosis clinic. PATIENT(S): Data on 240 pregnancies in 165 couples after a pregnancy with a serious chromosomal abnormality. RESULT(S): Autosomic trisomic pregnancy had occurred in 133 families. In these families, there were 193 new pregnancies 132 in women under 35 years and 61 in women over 35 years. The recurrence rate was 2.3% in the women under 35 years and 8.2% in the women over 35 years. Pregnancy had occurred in 18 families with a sex-chromosomal abnormality. In these families, there were 24 new pregnancies, 21 in women under 35 years and 3 in women over 35 years. All pregnancies were chromosomally normal. Some other serious chromosomal abnormality had occurred in 14 families. In these families, there were 23 new pregnancies. Chromosomal abnormality recurred in two families: in a woman under 35 years and in a woman over 35 years. CONCLUSION(S): The high recurrence rate of chromosomal abnormalities even in women under 35 years warrants fetal chromosomal investigation in new pregnancies.