Oocyte and embryo quality in obese patients undergoing in vitro fertilization (IVF)

Abstract

OBJECTIVE: Obesity is associated with poor reproductive outcome, but little is known about the mechanism by which this occurs. Our objective was to evaluate the effect of maternal obesity on oocyte and embryo quality.DESIGN: Retrospective cohort.MATERIALS AND METHODS: Women undergoing IVF in our program in 2008 were categorized by body mass index (BMI) as underweight (≤18.4 kg/m2), normal weight (18.5-24.9), overweight (25.0-29.9), or obese (Class I 30.0-34.9; Class II 35.0-39.9; Class III ≥40.0). Linear, logistic, and Poisson regression were used as indicated to estimate the effect of BMI on outcomes, adjusting for potential confounders. Results were expressed as adjusted odds ratios (OR) or incidence rate ratios with 95% confidence intervals (CI), using normal weight women as the referent.RESULTS: 893 women were included: 24 underweight, 549 normal weight, 161 overweight, 77 Class I, 41 Class II, and 41 Class III, of which 11 had a BMI ≥45. Compared to women with normal BMI, those with Class II and III obesity had significantly lower peak estradiol levels (2123 pg/mL vs 1664 and 1366, p<0.05), fewer oocytes retrieved (15 vs 11 and 12, p<0.0001), and fewer total embryos (14 vs 11 and 12, p<0.0001). Adjusting for polycystic ovary syndrome (PCOS), women with Class III obesity had lower live birth rates (OR=0.4, CI=0.18-0.88) and a 29% greater incidence of immature (germinal vesicle or metaphase I) oocytes (CI=1.11-1.81) compared to those with normal BMI. Underweight women had a 42% higher incidence of oocyte immaturity (CI=1.02-1.63) and a lower odds of embryo transfer per retrieval (OR=0.18, CI=0.06-0.61) compared to normal BMI. Embryo cell number, fragmentation, and symmetry were not associated with BMI.CONCLUSION: Morbid obesity was associated with increased oocyte immaturity and lower live birth rates. Oocyte maturity was also compromised in underweight women. BMI may impact IVF outcome at the level of the oocyte. Ongoing analyses will include an additional year of patients and focus on women with PCOS. OBJECTIVE: Obesity is associated with poor reproductive outcome, but little is known about the mechanism by which this occurs. Our objective was to evaluate the effect of maternal obesity on oocyte and embryo quality. DESIGN: Retrospective cohort. MATERIALS AND METHODS: Women undergoing IVF in our program in 2008 were categorized by body mass index (BMI) as underweight (≤18.4 kg/m2), normal weight (18.5-24.9), overweight (25.0-29.9), or obese (Class I 30.0-34.9; Class II 35.0-39.9; Class III ≥40.0). Linear, logistic, and Poisson regression were used as indicated to estimate the effect of BMI on outcomes, adjusting for potential confounders. Results were expressed as adjusted odds ratios (OR) or incidence rate ratios with 95% confidence intervals (CI), using normal weight women as the referent. RESULTS: 893 women were included: 24 underweight, 549 normal weight, 161 overweight, 77 Class I, 41 Class II, and 41 Class III, of which 11 had a BMI ≥45. Compared to women with normal BMI, those with Class II and III obesity had significantly lower peak estradiol levels (2123 pg/mL vs 1664 and 1366, p<0.05), fewer oocytes retrieved (15 vs 11 and 12, p<0.0001), and fewer total embryos (14 vs 11 and 12, p<0.0001). Adjusting for polycystic ovary syndrome (PCOS), women with Class III obesity had lower live birth rates (OR=0.4, CI=0.18-0.88) and a 29% greater incidence of immature (germinal vesicle or metaphase I) oocytes (CI=1.11-1.81) compared to those with normal BMI. Underweight women had a 42% higher incidence of oocyte immaturity (CI=1.02-1.63) and a lower odds of embryo transfer per retrieval (OR=0.18, CI=0.06-0.61) compared to normal BMI. Embryo cell number, fragmentation, and symmetry were not associated with BMI. CONCLUSION: Morbid obesity was associated with increased oocyte immaturity and lower live birth rates. Oocyte maturity was also compromised in underweight women. BMI may impact IVF outcome at the level of the oocyte. Ongoing analyses will include an additional year of patients and focus on women with PCOS.