Even With Higher Ovarian Response to IVF, Black Women Still Had Fewer Babies

ANAHEIM, Calif. -- Despite having higher rates of ovarian response to gonadotropin stimulation during in vitro fertilization (IVF), Black women had significantly lower live birth rates compared with white women, according to a retrospective single-center study.

In the cohort of nearly 5,000 women, Black women had a live birth rate of 47.3% versus 56.9% for white women (adjusted rate ratio 0.83, 95% CI 0.72-0.96, P=0.01), even though they had a higher Ovarian Sensitivity Index (6.19 vs 5.23, respectively; P=0.003), reported Iris Lee, MD, of the University of Pennsylvania in Philadelphia.

Black women also had a significantly lower clinical pregnancy rate compared with white women (59.5% vs 70.5%, respectively; P=0.009).

While ovarian response after gonadotropin stimulation is known to predict live births in the general population, this study shows this may not the case for Black women, Lee said during her presentation at the American Society for Reproductive Medicine annual meeting.

"Doing well in stimulation is great, and we want that for everyone," Lee told MedPage Today. "But you can do as well as you want in stimulation and still not have a baby."

Hispanic patients also had a higher Ovarian Sensitivity Index than white patients (6.41; P=0.01), and while they trended towards lower live birth rates, this finding was not significant (P=0.08).

Several studies have documented lower live birth rates with IVF among Black and Hispanic women, Lee noted. But few have been able to parse out why these disparities exist.

"Because the treatment process is so complex, and there's so many different steps along the way that could be affecting outcomes, it's very difficult to actually understand why the disparity is happening," she added.

Stimulation is just the first step in IVF, followed by fertilization, embryo development, and implantation.

Given these findings, Lee said future research should aim to investigate how other phases of the IVF treatment process contribute to racial disparities in pregnancy outcomes. She said that looking at the presence of uterine fibroids, for example, which are more common among Black women and may cause pregnancy complications, could provide insights into how disparities are influenced by the implantation phase.

While this study gets closer to understanding why racial disparities exist in IVF, Lee said there is a need for more research to investigate not only potential biological mechanisms for these gaps, but also social and economic factors.

"It's somewhat frustrating in a way, because I feel like there are now more questions than answers," she added. "But I think it's helping us ask at least the right questions."

Lee and colleagues conducted this single-center retrospective cohort study to evaluate the relationships between race/ethnicity, ovarian response during gonadotropin stimulation, and live births. The study included women ages 18 to 45 who underwent ovarian stimulation for any indication from May 2015 to July 2022. Patients self-reported race and ethnicity in medical records.

They included 4,785 cycles in their analysis of ovarian response, and 2,287 first fresh cycles in their analysis of pregnancy outcomes. Overall, 70% of cycles were among white women, 11.5% among Black women, and 3.5% among Hispanic women.

Black patients tended to be about a year older than those in the other groups (37 vs 36 years). Black and Hispanic patients had higher BMIs than white patients. Duration of infertility was highest among Hispanic women.

The researchers adjusted their analyses for covariates including age, BMI, and infertility diagnosis.

Black and Hispanic patients continued to have higher ovarian sensitivity in an analysis of first retrievals only, as well as in an analysis that excluded patients with diminished ovarian reserve.

Across all racial and ethnic groups, ovarian sensitivity was a modest predictor of live birth from first retrieval.

Differences in miscarriage rates across groups were not significant.

Lee acknowledged that this study was limited by its retrospective nature, and its small sample of Hispanic patients. She also noted that her team was unable to account for the presence of fibroids, as well as socioeconomic status.

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