In vitro fertilization access should not be restricted among women with obesity, according to a recent study published in the American Journal of Obstetrics & Gynecology.
Takeaways
- Obesity, defined as a boy mass index (BMI) of 30 kg/m2 or higher, affects nearly a quarter of reproductive-aged women in the United States, leading to various reproductive issues such as infertility, anovulation, and irregular menstrual cycles.
- There's a growing trend of obese women seeking in vitro fertilization (IVF) treatment, but this population experiences reduced clinical pregnancy rates and increased risks of obstetrical complications and adverse neonatal outcomes, prompting some fertility centers to restrict access to IVF for those with a BMI of 40 kg/m2 or higher.
- A retrospective cohort study evaluated how increasing BMI impacts IVF treatment outcomes, analyzing cycles categorized by BMI groups ranging from 30 to 50 kg/m2 or higher.
- Despite BMI variations, key IVF outcomes such as oocyte retrieval, fertilization rate, and embryo quality showed no significant differences across BMI groups, suggesting that IVF remains a viable option for obese patients.
- While some maternal and neonatal outcomes showed no significant differences across BMI groups, there were increased incidences of conditions like preeclampsia and gestational diabetes mellitus in higher BMI groups. However, overall, the study suggests similar outcomes from IVF and comprehensive care regardless of BMI, leading to the conclusion that IVF should not be withheld from obese patients.
Obesity is defined as body mass index (BMI) of 30 kg/m2 or higher and is reported in nearly 25% of reproductive-aged women in the United States. Adverse reproductive events associated with obesity include infertility, anovulation, and menstrual irregularities.
A rising trend in obese women seeking in vitro fertilization (IVF) treatment for obesity has been observed, with data indicating a significant reduction in clinical pregnancy among this population. Additionally, a high prepregnancy BMI has been associated with obstetrical complications and adverse neonatal outcomes. This has led very few fertility centers to offer IVF in patients with a BMI of 40 kg/m2 or greater.
Investigators conducted a retrospective cohort study to evaluate how increasing BMI impacts IVF treatment outcomes. Intracytoplasmic sperm injection (ICSI) and frozen embryo transfer cycles obtained between January 1, 2012, and April 30, 2020, were included in the analysis.
Cycles were categorized by BMI, with groups including 30 to 34.9, 35 to 39.9, 40 to 44.9, 45 to 49.9, and 50 kg/m2 or higher. An additional cohort of fresh IVF or ICSI and frozen embryo transfer cycles were used to determine maternal, pregnancy, and maternal outcomes.
Consultation with a maternal–fetal medicine specialist was provided to patients with a BMI of 40 kg/m2 or higher prior to treatment. A single embryo transfer was required in these patients to reduce multifetal gestation risk.
Patients underwent intravenous general anesthesia during oocyte retrieval. During the perioperative assessment, an anesthesiologist discussed medical history, anticipated anesthetic plan, instructions to take nothing by the mouth before the procedure, and any remaining questions from patients.
Live birth was measured as the primary outcome of the analysis. The number of mature oocytes obtained, blastulation rate, fertilization rate, and embryo quality were measured as IVF outcomes. Birthweight, preterm birth, neonatal intensive care unit (NICU) admission, over 5 days of NICU admission, and neonatal demise were measured as neonatal outcomes.
Pregnancy outcomes included miscarriage rate, multiple gestation rate, gestational diabetes mellitus, cesarean delivery, labor induction, hypertensive disorders of pregnancy incidence, postpartum hemorrhage, maternal length of stay over 5 days, and severe maternal morbidity incidence.
There were 2069 fresh IVF or ICSI and frozen embryo transfer cycles included in the analysis, 1008 in the 30 to 34.9 kg/m2 BMI group, 547 in the 35 to 39.9 kg/m2 BMI group, 277 in the 40 to 44.9 kg/m2 BMI group, 161 in the 45 to 49.9 kg/m2 BMI group, and 76 in the 50 kg/m2 or higher BMI group.
Oocyte age, serum anti-Müllerian hormone, and day 3 follicle-stimulating hormone did not significantly differ across BMI groups. Compared to other groups, the 50 kg/m2 or higher group had a greater proportion of Black patients.
The number of oocytes retrieved and number of mature oocytes retrieved did not significantly differ between groups, with means of 12.96 and 9.55, respectively. Additionally, the fertilization rate and blastulation rate had means of 76.96% and 46.80% across the overall study population, without significant variation between BMI groups.
A negative correlation was reported between BMI and the mean number of embryos transferred per cycle. Fifty percent to 69% of transfers were frozen embryo transfers, and the greatest proportion of excellent- and good-quality embryos were found in the 30 to 34.9 kg/m2, 35 to 39.9 kg/m2, and 40 to 44.9 kg/m2 BMI groups.
Rates of live birth, miscarriage, intrauterine fetal demise, single gestation, and twin gestation did not significantly differ between BMI groups, with means of 95.16%, 4.40%, 0.44%, 84.76%, and 15.24%, respectively. Gestational hypertension and preeclampsia also had similar rates of incidence across BMI groups.
Patients in the 50 kg/m2 or higher group had significantly increased preeclampsia incidence compared to the 30 to 34.9 kg/m2 BMI group, with an absolute risk reduction (aRR) of 2.75. The 45 to 49.9 kg/m2 BMI group had increased gestational diabetes mellitus incidence compared to the reference group, with an aRR of 2.38.
Placenta previa was significantly more common in the 40 to 44.9 kg/m2 and 45 to 49.9 kg/m2 groups, at 11.29% and 12%, respectively. Labor induction, cesarean delivery, postpartum hemorrhage, prolonged admission, and severe maternal morbidity did not significantly differ between BMI groups.
For neonatal outcomes, preterm birth and NICU admission were similar across BMI outcomes, but prolonged NICU admission was more common in the 50 kg/m2 or higher group than the 30 to 34.9 kg/m2 group, with an aRR of 2.61. Three cases of neonatal demise were reported, all in the 30 to 34.9 kg/m2 group.
These results indicated similar outcomes from IVF and comprehensive care among patients with an increased BMI compared to those with a lower BMI. Investigators concluded IVF should not be withheld from patients with obesity.
Reference
George JS, Srouji SS, Little SE, et al. The impact of increasing body mass index on in vitro fertilization treatment, obstetrical, and neonatal outcomes. Am J Obstet Gynecol. 2024;230:239.e1-14. doi:10.1016/j.ajog.2023.10.018
