As part of the global epidemic of obesity, an increasing percentage of patients seeking in vitro fertilization (IVF) for infertility treatment are obese, and it’s been reported that many of them experience disappointing outcomes.
The Center for Infertility and Reproductive Surgery at Brigham and Women’s Hospital is one of only a few in the U.S. offering IVF for patients with body mass index (BMI) ≥40 kg/m2. In fact, as part of a tertiary care hospital staffed by highly trained anesthesiologists, the Center performs oocyte retrievals and embryo transfers for patients with BMIs up to 60.
Andrea Lanes, PhD, of the Department of Obstetrics and Gynecology at the Brigham, Jenny S. George, MD, formerly of the Department and now at Reproductive Medicine Associates of Michigan, and colleagues recently conducted a retrospective study to examine the impact of increasing BMI on IVF, obstetric and perinatal outcomes. In the American Journal of Obstetrics & Gynecology, they report largely similar outcomes in patients with BMIs of 30 to 60.
IVF Treatment Outcomes and Embryo Transfer
Between January 1, 2012, and April 30, 2020, there were 2,069 fresh traditional IVF or intracytoplasmic sperm injections and frozen embryo transfer cycle starts at the Brigham:
- BMI 30 to 34.9—1,008 cycles (reference group)
- BMI 35 to 39.9—547 cycles
- BMI 40 to 44.9—277 cycles
- BMI 45 to 49.9—161 cycles
- BMI ≥50—22 cycles
The total number of oocytes retrieved, mature oocytes retrieved, fertilization rate, and blastulation rate were similar across BMI groups. The mean number of embryos transferred per transfer decreased with increasing BMI (1.70 in the reference group vs. 1.14 with BMI ≥50).
Patients in the three lower-BMI groups had the highest proportions of “excellent” and “good” quality embryos. The proportion of “fair” or “poor” quality embryos was 48% in the group with a BMI of 45 to 49.9 and 45% in the group with a BMI ≥50.
Pregnancy, Maternal, and Neonatal Outcomes
867 embryo transfer cycles resulted in an ongoing clinical pregnancy during the study period:
- BMI 30 to 34.9—457 cycles (reference group)
- BMI 35 to 39.9—238 cycles
- BMI 40 to 44.9—104 cycles
- BMI 45 to 49.9—46 cycles
- BMI ≥50—22 cycles
Pregnancy and maternal outcomes—BMI groups were comparable in live birth rate (primary outcome), singleton gestation, twin gestation, miscarriage rate, intrauterine fetal demise, incidence of gestational hypertension and preeclampsia, need for labor induction, need for cesarean delivery, postpartum hemorrhage, maternal hospital stay longer than five days and incidence of severe maternal morbidity.
Differences between groups were noted in:
- The incidence of preeclampsia with severe features—Significantly higher in the BMI ≥50 group than the reference group (adjusted relative risks [aRR], 2.75; 95% CI, 1.13–6.67)
- The incidence of gestational diabetes requiring medication—Significantly higher in the BMI 45–49.9 group than the reference group (aRR, 2.38; 95% CI, 1.11–5.12) but not significantly higher in the BMI ≥50 group
- Placenta previa—Significantly more likely in the BMI 40–44.9 group (RR, 4.53; 95% CI, 1.65–12.44) and the BMI 45–49.9 group (RR, 4.82; 95% CI, 1.37–16.98) than in the reference group
Neonatal outcomes—The incidence of preterm birth and the need for neonatal ICU admission did not vary significantly across BMI groups. However, infants born to patients in the BMI ≥50 group were more likely than those in the reference group to require NICU admission longer than five days (aRR, 2.61; 95% CI, 1.09–6.25).
Three neonates died during the study period, all born to patients in the BMI 30–34.9 group. The deaths were secondary to extreme prematurity and low birth weight.
The Brigham Approach to IVF in Obesity
In this study, BMI 30–34.9 was considered the reference because more than 40% of U.S. adults currently have BMI >30 (class I obesity). The results are reassuring and reinforce the practice of not withholding IVF from patients with obesity.
At the Brigham fertility center, all patients with BMI >40 are required to undergo consultation with a specialist in maternal–fetal medicine before initiating treatment. Those with type 2 diabetes are often co-managed with endocrinologists. All patients consult with obstetrical anesthesiologists in the third trimester.
At the time of embryo transfer, patients with BMI >40 are encouraged to transfer a single blastocyst or cleavage-stage embryo, regardless of patient age. The risk of chromosomal abnormalities is strongly correlated with increasing oocyte age, so this strategy may require patients of advanced maternal age to undergo more transfer attempts. However, considering the risks of preeclampsia and gestational diabetes in patients with BMI >40, and the potential for exacerbation of those risks during multifetal gestation, it is paramount to patient health to prioritize singleton pregnancies.
Fertility providers who currently lack the specialized training, experience or institutional resources required to safely care for patients with obesity should feel empowered to refer elsewhere per American College of Obstetrics and Gynecology guidelines.