BMI is not associated with pregnancy rates following transfer of non-aneuploid frozen embryos, according to research presented at the American Society for Reproductive Medicine's (ASRM) 2022 scientific congress. 

Analysis of over 55,000 IVF patients who had not experienced recurrent miscarriage or uterine factor infertility, was carried out by researchers from Northwestern University Feinberg School of Medicine, Chicago, Illinois. Researchers found no correlation between BMI – a measure obtained using a person's weight and height – and pregnancy rates following IVF when results were adjusted for age at transfer, race, number of children, prior pregnancy loss, smoking, ovulation disorder and other factors. Authors noted results taken from this analysis of the Society for Assisted Reproductive Technology Clinic Outcome Reporting System were contrary to other findings. 

'While previous studies suggested otherwise, this study failed to find an association between BMI and pregnancy loss following euploid frozen embryo transfer.' said Dr Marcelle Cedars, ASRM president.

The ASRM 2022 scientific congress also heard from other researchers exploring the role of BMI, overweight and obesity in fertility patients and their treatment outcomes. 

Another abstract presented results that showed maternal obesity was significantly correlated with increased risk of miscarriage following embryo transfer using donor eggs. In this single-centre study, researchers paired the recipients of 476 donor oocytes in different BMI categories (obese >30 or non-obese <30) who had similar age, type of sperm used, number of previous children and ethnicity. They found a small, but significant increase in the risk of miscarriage in obese women when adjusting for variables. 

Researchers from Northwell Health Fertility and North Shore University Hospital, both in New York,  presented data showing that restricting access to fertility treatment on the basis of BMI, could contribute to reducing access to IVF for people who are black or Hispanic. Authors of the abstract had measured the BMI of 3350 patients who wanted to initiate fertility treatment at a single clinic. Analysis showed that black and Hispanic patients were more likely to have a BMI over 40, and that lower BMI and being white were both positively associated with initiating fertility treatment there. They warned BMI cut-offs in eligibility criteria for treatment may contribute to this disparity. 

A small study of 97 women carried out during the COVID-19 pandemic by researchers from Tufts Medical Centre and Boston IVF, both in Boston, Massachusetts, sought to analyse the effectiveness of remote support to lose weight in obese women with infertility. Obese women with a mean BMI 43.2 of were given access to a multi-disciplinary obesity management program delivered through a telehealth platform, including a monthly video call with a board-certified obesity medicine physician and a registered dietician. Participants reported a mean weight loss of 9.7 percent and 15.4 percent of patients were currently pregnant, the scientific congress was told.

Sources and References

• 19 October 2022. American Society for Reproductive Medicine
  Pregnancy outcomes do not decline with increasing body mass index: An analysis of 56,564 single euploid frozen embryo transfers from the SART CORS database

• 19 October 2022. American Society for Reproductive Medicine
  Obesity is associated with increased miscarriage rates in paired sibling donor oocyte recipient cycles

• 19 October 2022. American Society for Reproductive Medicine
  On race, BMI thresholds, and infertility treatment - examining the outcomes of patients who exceed BMI thresholds at first visit

• 19 October 2022. American Society for Reproductive Medicine
  An effective telehealth based multidisciplinary approach to weight loss in women with obesity seeking treatment for infertility

Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.