Does increased body mass index (BMI) have an adverse effect on uterine receptivity?

Abstract

Objective: Anonymous oocyte donation offers opportunity for investigating uterine receptivity. Studies to date have shown an inconsistent relationship between increased BMI and implantation. Implantation was starkly lower in oocyte donation cycles for BMI ≥ 30 [14% (95% CI 8–20)] versus BMI <30 [25% (23–28)] (Cano et al., Fertil Steril 2001;76:S160–1). In contrast, a case-control study found no adverse effect of increased BMI on implantation in non-oocyte donation cycles (Lashen et al., Hum Reprod 1999:712–5). The objective of the present analysis was to study uterine receptivity and BMI in an anonymous oocyte donation program with standardized protocols and programmed hormone replacement.Design: Retrospective cohort studyMaterials/Methods: 97 consecutive recipient women underwent embryo transfers after anonymous oocyte donation between 01/96 and 12/00. In one instance, BMI was unavailable and subject data were excluded from analysis. Body mass was stratified into three groups: BMI≤25, 25< BMI >30, and BMI≥30. Endometrial preparation involved GnRH agonist down regulation and then estradiol/progesterone supplementation to induce receptive endometrium. All embryo transfers followed thaw of embryos cryopreserved at the pronuclear stage.Results: Using ANOVA or χ2 analysis as appropriate, variables were analyzed according to BMI strata as shown in the table. Implantation rates were not significantly different among the groups (P = 0.94). Using multiple linear regression analysis with implantation as the dependent variable, recipient age and BMI were non-significant independent variables. Tabled 1Body Mass Index (BMI)≤25 (n = 59)25 & <30 (n = 25)≥30 (n = 12)P- valueAge39.2 ± 6.341.6 ± 5.140.9 ± 6.00.22Embryos transferred2.9 ± 0.63.0 ± 0.52.8 ± 0.60.63Embryo quality1.1 ± 0.50.9 ± 0.40.9 ± 0.40.34No. of blastomeres5.2 ± 1.25.5 ± 0.84.7 ± 1.10.13Endometrial thickness (mm)9.8 ± 1.910.2 ± 2.310.2 ± 1.80.73Implantation rate (%)2827290.94Delivery rate (%)42.34041.60.98 Open table in a new tab Conclusions: Increased BMI does not appear to have an adverse effect upon uterine receptivity. This conclusion is made in the context of standardized protocols for embryo number, embryo quality, embryo transfer and endometrial preparation. The current report, however, lacks sufficient power to be definitive. It is estimated that a sample of 55 with BMI≥30 is needed to have 80% power to detect a difference from the implantation rate of 14% (95% CI 8–20) reported by Cano et al.Supported by: Mayo Foundation. Objective: Anonymous oocyte donation offers opportunity for investigating uterine receptivity. Studies to date have shown an inconsistent relationship between increased BMI and implantation. Implantation was starkly lower in oocyte donation cycles for BMI ≥ 30 [14% (95% CI 8–20)] versus BMI <30 [25% (23–28)] (Cano et al., Fertil Steril 2001;76:S160–1). In contrast, a case-control study found no adverse effect of increased BMI on implantation in non-oocyte donation cycles (Lashen et al., Hum Reprod 1999:712–5). The objective of the present analysis was to study uterine receptivity and BMI in an anonymous oocyte donation program with standardized protocols and programmed hormone replacement. Design: Retrospective cohort study Materials/Methods: 97 consecutive recipient women underwent embryo transfers after anonymous oocyte donation between 01/96 and 12/00. In one instance, BMI was unavailable and subject data were excluded from analysis. Body mass was stratified into three groups: BMI≤25, 25< BMI >30, and BMI≥30. Endometrial preparation involved GnRH agonist down regulation and then estradiol/progesterone supplementation to induce receptive endometrium. All embryo transfers followed thaw of embryos cryopreserved at the pronuclear stage. Results: Using ANOVA or χ2 analysis as appropriate, variables were analyzed according to BMI strata as shown in the table. Implantation rates were not significantly different among the groups (P = 0.94). Using multiple linear regression analysis with implantation as the dependent variable, recipient age and BMI were non-significant independent variables. Tabled 1Body Mass Index (BMI)≤25 (n = 59)25 & <30 (n = 25)≥30 (n = 12)P- valueAge39.2 ± 6.341.6 ± 5.140.9 ± 6.00.22Embryos transferred2.9 ± 0.63.0 ± 0.52.8 ± 0.60.63Embryo quality1.1 ± 0.50.9 ± 0.40.9 ± 0.40.34No. of blastomeres5.2 ± 1.25.5 ± 0.84.7 ± 1.10.13Endometrial thickness (mm)9.8 ± 1.910.2 ± 2.310.2 ± 1.80.73Implantation rate (%)2827290.94Delivery rate (%)42.34041.60.98 Open table in a new tab Conclusions: Increased BMI does not appear to have an adverse effect upon uterine receptivity. This conclusion is made in the context of standardized protocols for embryo number, embryo quality, embryo transfer and endometrial preparation. The current report, however, lacks sufficient power to be definitive. It is estimated that a sample of 55 with BMI≥30 is needed to have 80% power to detect a difference from the implantation rate of 14% (95% CI 8–20) reported by Cano et al. Supported by: Mayo Foundation.