Joint impact of maternal age and BMI on cumulative live birth following in vitro fertilization

To evaluate the joint influence of age and BMI on cumulative live birth, in order to determine when taking time off from attempting conception to achieve a lower BMI may be detrimental to the cumulative live birth rate (CLBR) following IVF, and to develop a personalized counseling tool. Retrospective study using linked fresh and frozen cycles from 1/2014-12/2015 from the Society for Reproductive Technology Clinic Outcome Reporting System (SART CORS). Demographic and outcome data from 51,959 fresh and 16,067 linked frozen embryo transfer (FET) IVF cycles performed between 1/2014-12/2015 were obtained from SART CORS. Poisson and logistic regression were used to calculate risk and odds ratios with 95% confidence intervals (CI) to determine differences in implantation and clinical pregnancy, respectively, among first fresh IVF cycles compared across age (y) and BMI (kg/m2) categories. Cox regression was used to calculate hazard ratios with 95% CI to determine differences in CLBR using fresh plus linked FET cycles. Models were adjusted for age, BMI, AMH, smoking, prior cycles, number of embryos transferred, blastocyst transfer, and embryo grade. CLBRs for age and BMI combinations were then determined to create a counseling tool for ascertaining whether achieving a lower BMI at a given age is likely to result in an improvement or detriment to the likelihood of live birth following IVF. There were 50,711 first fresh autologous cycles intended for transfer resulting in 15,041 live births, for an overall LBR of 30% per cycle start. Of these, 23,294 (46%) of women had a BMI ≥25. The implantation rate, clinical pregnancy rate, and CLBR decreased with increasing BMI and age (linear trend p<0.001 for all). For some age and BMI combinations, taking time to lose weight prior to IVF may be beneficial: for example, a 31-year-old with Class III Obesity would have a CLBR of 40%, whereas a 33-year-old with Class I Obesity would have a CLBR of 54% (Table). For other combinations, taking time to lose weight may be detrimental: a 39-year-old with Class II Obesity would have a CLBR of 28%, while a 40-year-old with Class I obesity or a 41-year-old with overweight would have a CLBR of 21% and 15%, respectively. In general, women <35y with BMI ≥40 may increase their live birth rate through weight loss and achievement of a BMI <35 prior to IVF, whereas older women with overweight or obesity may actually decrease their likelihood of live birth if they delay attempting conception to lose weight. Counseling women about weight loss prior to IVF should consider the combination of age and BMI.Tabled 1Cumulative Likelihood of Live Birth (%) Based on Maternal Age and BMIBMI (kg/m2)Age (y)<18.5 (Underweight)18.5-24.9 (Normal Weight)25.0-29.9 (Overweight)30.0-34.9 (Class I Obesity)35.0-39.9 (Class II Obesity)40.0-44.9 (Class III Obesity)≥45.0 (Morbid Obesity and Superobese)<30129/199 (65%)2299/3606 (64%)980/1654 (59%)491/823 (60%)208/419 (50%)61/128 (48%)20/54 (37%)3163/104 (61%)1040/1761 (59%)436/766 (57%)179/329 (54%)78/163 (48%)26/65 (40%)6/21 (29%)3355/122 (45%)1144/2053 (56%)472/914 (52%)243/453 (54%)89/203 (44%)28/75 (37%)10/37 (37%)3560/127 (47%)1056/2100 (50%)414/931 (44%)207/450 (46%)102/241 (42%)32/73 (44%)11/36 (31%)3734/87 (39%)669/1724 (39%)333/875 (38%)133/377 (35%)73/192 (38%)18/74 (24%)14/43 (33%)3914/74 (19%)389/1546 (25%)216/814 (27%)115/423 (27%)61/215 (28%)18/80 (23%)3/27 (11%)4011/59 (19%)280/1387 (20%)128/682 (19%)73/349 (21%)27/156 (17%)7/57 (12%)5/22 (23%)416/71 (8%)167/1238 (13%)94/613 (15%)33/267 (12%)24/125 (19%)6/44 (14%)1/19 (5%)421/33 (3%)108/1020 (11%)46/527 (9%)29/266 (11%)10/117 (9%)5/45 (11%)2/17 (12%)≥430/59 (0%)43/1544 (3%)32/726 (4%)17/351 (5%)3/158 (2%)3/57 (5%)0/17 (0%) Open table in a new tab