BACKGROUND: The increased risk of a trisomic pregnancy with a woman's age arises from an increased rate of meiotic non-disjunction in the oocytes. It has been hypothesized that the increase in meiotic errors is related to the decreasing number of oocytes with age. Our aim was to assess the relation between trisomic pregnancy and three parameters of oocyte quantity. METHODS: In a Dutch nationwide database on in vitro fertilization (IVF) treatment from 1983 to 1995, we identified 28 women with a trisomic pregnancy conceived via or within 1 year from IVF treatment. We selected five age-matched controls with a healthy child for each trisomy case. We performed a case-control study to examine whether trisomy cases more often had a history of ovarian surgery and a lower response to ovarian hyperstimulation than controls. Subsequently, cases and controls were followed to compare the incidence of signs of menopause at the end of the study period as self-reported by questionnaire. RESULTS: Logistic regression analysis showed an association between trisomic pregnancy and a history of ovarian surgery [odds ratio (OR) 3.3; 95% confidence interval (CI): 1.0-10.5; P = 0.04] and between trisomic pregnancy and retrieval of < or = 4 oocytes during IVF treatment (OR 4.0; 95% CI: 1.4-11.5; P = 0.01). The adjusted OR for signs of menopause associated with trisomic pregnancy was 5.7 (95% CI: 1.1-29.9; P = 0.04). CONCLUSIONS: Our results suggest that IVF-treated women with a reduced ovarian follicle pool are at increased risk of a trisomic pregnancy, independent of their age. Our findings support the hypothesis that follicle pool size and not chronological age determines a woman's trisomy risk. Since a questionnaire was used, we cannot fully exclude the possibility of selection bias in this study.
BACKGROUND: The increased risk of a trisomic pregnancy with a woman's age arises from an increased rate of meiotic non-disjunction in the oocytes. It has been hypothesized that the increase in meiotic errors is related to the decreasing number of oocytes with age. Our aim was to assess the relation between trisomic pregnancy and three parameters of oocyte quantity. METHODS: In a Dutch nationwide database on in vitro fertilization (IVF) treatment from 1983 to 1995, we identified 28 women with a trisomic pregnancy conceived via or within 1 year from IVF treatment. We selected five age-matched controls with a healthy child for each trisomy case. We performed a case-control study to examine whether trisomy cases more often had a history of ovarian surgery and a lower response to ovarian hyperstimulation than controls. Subsequently, cases and controls were followed to compare the incidence of signs of menopause at the end of the study period as self-reported by questionnaire. RESULTS: Logistic regression analysis showed an association between trisomic pregnancy and a history of ovarian surgery [odds ratio (OR) 3.3; 95% confidence interval (CI): 1.0-10.5; P = 0.04] and between trisomic pregnancy and retrieval of < or = 4 oocytes during IVF treatment (OR 4.0; 95% CI: 1.4-11.5; P = 0.01). The adjusted OR for signs of menopause associated with trisomic pregnancy was 5.7 (95% CI: 1.1-29.9; P = 0.04). CONCLUSIONS: Our results suggest that IVF-treated women with a reduced ovarian follicle pool are at increased risk of a trisomic pregnancy, independent of their age. Our findings support the hypothesis that follicle pool size and not chronological age determines a woman's trisomy risk. Since a questionnaire was used, we cannot fully exclude the possibility of selection bias in this study.