Infertility is a devastating disease that spans all races and socioeconomic groups. One in 8 couples has difficulty conceiving and for anyone trying to have a baby, the diagnosis of infertility is life altering.
Fortunately, there have been many advances in the field of reproductive medicine over the past three decades and there are many cutting edge technologies available to help women conceive.
Understanding the Causes of Infertility
Infertility can be due to either male or female factors. Male factors are typically due to a low sperm count, poor sperm motility (the ability to swim) or abnormal morphology (the shape of the sperm). Treatments such as intrauterine insemination (IUI) where the sperm is placed directly into the uterus, or in-vitro fertilization with intracytoplasmic sperm injection (IVF/ICSI) where the sperm is placed directly into the egg can overcome most causes of male factor infertility.
The causes of female infertility are more diverse and complex. Female infertility can be broken down into causes related to the ovary (diminished ovarian reserve, polycystic ovarian syndrome, ovulatory dysfunction), causes related to damaged fallopian tubes, uterine factors such as fibroids or adenomyosis (the presence of glandular tissue infiltrating the muscle layer of the uterus) or other pelvic diseases such as endometriosis. Treatments are targeted towards the underlying cause of fertility problems and are as diverse as surgery, ovulation induction with oral or injectable medications, intrauterine insemination and IVF
Analyzing Ethnicity and Infertility
There has been a flurry of publications that have examined racial disparity in the arena of infertility. The Society for Assisted Reproductive Technologies (SART) collects data on more than 90% of all clinics performing IVF in the USA. The data gathered from SART can be used for clinical outcomes research, allowing valuable information to be gleaned.
In 2006, SART data analysis discovered that Asian ethnicity was found to be an independent risk factor for worse outcomes that did not result in conception or lasting pregnancy. The dataset included 25,843 Caucasian and 1,429 Asian women.
In 2007, the same SART data set was analyzed but with a focus on IVF outcomes in Black women. There were 3,666 Black and 68,606 White women included in the analysis and the relative risk of not achieving a live birth was 1.21 in Black women compared to White women. Other studies that have also used the SART database have similarly found significant disparity.
A major criticism of these SART database studies is that there are wide differences in IVF success rates between clinics. It has also been argued that minority access to care may be limited to clinics with worse outcomes.
As a result of these limitations, our group decided to study whether racial disparity in IVF outcomes existed in racially diverse Chicago. Illinois affords an excellent opportunity for outcomes based research as Illinois is one of 15 states with mandated infertility coverage, greatly increasing access to care. The Illinois mandate requires up four covered cycles of IVF to achieve the first live birth and up to two covered cycles to achieve a second live birth. Data was collected over a 3-year period from January 2010 to December 2012. In the largest single site study on racial disparities in IVF outcomes to date, approximately 4,045 patients were included (3,003 White, 213 Black, 541 Asian, 288 Hispanic).
Similar to the SART database findings, outcomes in Black women were markedly worse when compared to White women. The clinical pregnancy rate was significantly lower (24.4% vs. 36.2%) and the spontaneous abortion rate was significantly higher (28.9% vs. 14.6%,). Most important, the live birth rate among Black women was almost half that of White women (16.9% vs. 30.7%)
Racial disparities were present but not as marked in the Asian population. Asian women required a longer duration of stimulation (10.3 vs. 9.9 days, p=0.001), had fewer eggs retrieved and had fewer surplus five day embryos to freeze compared to White women Asian women also had a significantly lower clinical pregnancy rate (31.4% vs. 36.2%,) and live birth rate (24.0% vs 30.7) compared to White women. Spontaneous abortion rates and multiple pregnancy rates were not significantly different between groups. Outcomes in Hispanic women were similar to White women.
Why the Disparity?
There have been several modifiable risk factors identified to date that are known to impact IVF outcomes. One such factor is the presence of uterine fibroids. Fibroids are benign smooth muscle tumors and are three times more common in Black women than White women (37% vs. 11%). Fibroids are a known cause of infertility and spontaneous abortion and may be a large reason for disparity in outcomes. Traditionally, fibroids have been treated by surgery, however new and emerging therapies are being discovered. There is great promise in this area and further studies are needed to assess whether removing or treating fibroids prior to IVF will improve live birth rates.
Obesity is a modifiable risk factor that has been associated with lower clinical pregnancy rates and higher spontaneous abortion rates. This is also a modifiable risk factor and reduction in body mass index (BMI) prior to IVF has been shown to improve outcomes.
Asian ethnicity was associated with worse ovarian reserve and responsiveness. This is likely genetic, but further research is needed to fully understand the cause of these differences.
Racial disparity in infertility is a complex problem with multiple layers. The results of any studies must be interpreted with caution and not generalized. Black women are not intrinsically less fertile than White women. Furthermore, racial disparity in outcomes of other fertility treatments such as surgery, ovulation induction, and intrauterine insemination have not been studied.
Research findings such as these shed light on how we can understand the causes of infertility and how they pertain to ethnicity. As more information is uncovered, we will adapt and improve our treatment protocols to increase success for patients. As always, our goal is to help our patients build the family of their dreams.