Why severely obese women have trouble with IVF


One third of American women of childbearing age struggle with obesity. Severe obesity affects health and fertility. Often they have less successful reproductive outcomes but the reasons for that are unknown. Because of a new study by Catherine Racowsky, PhD, director of the Assisted Reproductive Technologies Laboratory at Brigham and Women’s Hospital (BWH) reveals some of the underlying reasons why by giving insight into the underlying mechanisms.

Researchers looked at 276 eggs that failed to fertilize

The research team looked at 276 mature human eggs that failed to fertilize from women undergoing in vitro fertilization (IVF). Of those, 105 eggs were from severely obese women with a body mass index (BMI) between 35 and 50.1. There were 171 eggs from women with a normal BMI. The measurement is determined by a person’s height and weight and is considered a fair standard for body fatness.

They gained new insights into the effect of BMI on egg health

“This study is the first to shed light on how BMI might adversely affect egg quality in women,” explained Dr. Racowsky. “These observations provide novel insight into a possible cause for the reduced likelihood of success with IVF in severely obese women.”

Abnormalities with obese women’s eggs were found

In order for an egg to have the best chance of fertilization, it should be mature with one spindle, a critical egg structure, on which is attached one organized set of chromosomes. In severely obese women, their eggs tend to have multiple spindles and disorganized chromosomes.

Racowsky’s team found that nearly 60% of the eggs from severely obese group had two spindles while only 35% from the normal group did. They also found that among eggs with one spindle, nearly 30% from the obese group had disorganized chromosomes compared to 9% from the normal group.

Source: MedicalNewsToday, Brigham and Women’s Hospital


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