Houston, Texas, USA : IVF is less successful in black women even though they produce more viable eggs and embryos – and researchers admit they don’t know why. African American women have lower success rates from IVF – despite yielding more eggs and embryos than white women.
Most believe that the most important number to look for is how many eggs and embryos are retrieved.
But new research shows that there may be other factors at play, especially for black patients, who have a 14 percent lower live birth rate than white women, according to data from a large clinic in Washington, DC.
Some of the discrepancy can be explained by the fact that the African American patients were more likely to be older, with a higher BMI.
However, the researchers of the study warn much of it is likely caused by biological factors that we don’t understand because black women are under-studied in medical research.
The paper, being presented today at the conference for the American Society for Reproductive Medicine in Denver, is an analysis of 36,000 patients that were treated at Shady Grove Fertility between 2004 and 2016.
They showed that, in this cohort (unlike the general population), African American women were less likely to suffer uterine disorders, and they responded better to the ovarian stimulation given to extract eggs.
They produced more eggs and more healthy embryos were fertilized.
Pregnancy rates, however, were significantly lower in black women – 42 percent compared to 49 percent of white women.
The rate of women who miscarried was much higher – 26 percent compared to 18 percent.
And the live birth rate was 31 percent, compared to 40 percent for white women, a relative percentage difference of 14 percent.
‘This important research points out the urgent need to better understand the factors that may contribute to these racial disparities,’ said Christos Coutifaris MD, PhD, president of the American Society for Reproductive Medicine.
‘Improved knowledge of biological and other factors contributing to successful implantation and placenta development could lead to higher success rates and save patients from the heartbreak of a failed cycle or pregnancy loss.’
It is hardly the first study to highlight the racial gap in results.
In 2016, a study by the University of Chicago of 4,000 women found black women were half as likely to conceive.
The same year, a study by Columbia University Medical Center found the same even when using donor eggs, and even when controlling for uterine disorders: black women were much less likely to get pregnant than white women.
The new research paper being presented at ASRM sought to dig deeper at the underlying causes – and what they turned up did more to confirm the racial gap in medical research than identify concrete issues to work on.
The results agree with an earlier study that concluded that black women have worse IVF outcomes versus white women.
In that earlier study, Leigh A. Humphries, from the Beth Israel Deaconess Medical Center in Boston, and colleagues conducted a systematic literature search to identify studies that compared clinical pregnancy rates and live birth rates for more than two racial and/or ethnic groups after non-donor IVF cycles.
The researchers identified 24 studies. Based on the five U.S. registry-based studies, black, Hispanic, and Asian women had lower clinical pregnancy rates and/or live birth rates after IVF, compared with white women. Significant disparities in these primary outcomes were similarly seen in clinic-specific studies, potentially attributable to differences in infertility diagnosis, spontaneous abortion, and obesity. Definitions of race/ethnicity, inclusion of first cycles versus multiple cycles for individual women, and collected covariates varied between studies. Limitations of studies included sample size, inadequate adjustment for confounding, selection bias, and extensive missing data.
“Although current evidence points to race and ethnicity, especially black race, as strong predictors of poorer outcomes after IVF, the utility of results is constrained by the limitations described,” the authors write.
A third study by the University of Chicago also concluded that black women undergoing in vitro fertilization (IVF) are only about half as likely as white women to become pregnant using the popular assisted reproduction technique and the racial disparity persists even when donor eggs are used.
In the University of Chicago study, about 31 percent of white patients became pregnant after IVF, compared to about 17 percent of black patients.
Analyzing more than 4,000 IVF cycles over two years to tease out the impact of race, scientists from University of Chicago also found that miscarriage after IVF—where eggs and sperm are joined in a lab and implanted in the woman’s uterus—occurred twice as often among blacks than whites.
These racial differences remained even though the researchers controlled for factors affecting pregnancy such as age, body-mass index (BMI, a measurement of weight vs. height), hormone levels and smoking. Asian women also experienced somewhat lower live birth rates than whites after IVF, but rates among Hispanic women were comparable to whites.
“We were just struck by these outcomes,” said study author Dr. Eve Feinberg, an assistant clinical professor at University of Chicago Medical Center and a physician at Fertility Centers of Illinois. “They had been reported previously in other studies, but our study, which is quite large, really confirmed those other findings.”
The study was presented Monday at the American Society for Reproductive Medicine (ASRM) annual meeting in Honolulu. Research presented at scientific meetings typically has not been published or peer-reviewed and results are considered preliminary.
Used in the United States since 1981, IVF is one of the most common forms of assisted reproduction. About 65,000 babies were born in the United States in 2012 through 176,000 assisted reproduction cycles, typically costing upwards of $10,000 apiece, according to the U.S. Centers for Disease Control and Prevention.
In another study being presented at the ASRM meeting, researchers from Columbia University Medical Center in New York found that racial differences for IVF success persisted between white and black women even when donor eggs were used.
In that research, led by Dr. Lisa Carey Grossman, uterine conditions such as fibroids or prior cesarean surgery were taken into account. Because black women have higher incidences of such conditions, the scientists compared black and white egg donor recipients who had similar uterine histories.
Despite that, black women still experienced significantly lower embryo implantation rates than whites—30.4 percent compared to 36.3 percent, Grossman said.
Dr. Edward Illions, a reproductive endocrinologist at Montefiore Medical Center in Hartsdale, N.Y., who wasn’t involved in the new research, said he has observed the same racial disparities in IVF outcomes in his own practice.
“I’m not actually surprised, because the [medical] literature before this almost uniformly has shown a lower success rate in African-American women compared to Caucasians,” said Illions, also an associate professor of clinical obstetrics, gynecology and women’s health at Montefiore Institute for Reproductive Medicine.
“In most of the studies also, the BMIs of African-American women have been dramatically higher,” he added. “We know from lots of data that women with higher BMIs have worse IVF outcomes, even with donor eggs.”
Illions said scientists aren’t yet sure why higher BMI is linked to lower IVF success. “It has to do with uterine receptivity,” he said, but he added that the exact cause hasn’t been pinpointed.
The experts agreed that more large-scale research is needed to determine why racial disparities in IVF outcomes persist.