Strengths and Limitations
The strength of our study is the unique and large international Black patient population at BMC that created the potential to study ethnic differences within race. We are the first to describe differences in infertility etiology within a race. Furthermore, the robust chart analysis used in this study allowed for more accurate stratification of race and ethnicity as well as confirmation of infertility diagnoses without sole dependence on ICD-9 coding. The potential for misclassification bias was limited by using a combination of race, place of birth, and language to help confirm the racial and ethnic identity of each woman. By identifying differences in infertility etiologies within the Black race, our study highlights the importance of ethnic, environmental, and cultural factors in the genesis of infertility.
Limitations of our study include its retrospective nature and the small sample size for each ethnic subgroup. We may have been underpowered to see small differences between groups. We attempted to limit selection bias inherent in retrospective studies by having two independent investigators conduct chart reviews. In addition, as ICD-9 codes were used to identify the potential cohort, it is possible that women with improper ICD-9 infertility coding were missed. Lastly, the duration of residency in the United States for Black Haitian or Black African women could not be ascertained and controlled for to quantify the impact of U.S. cultural and environmental influences on their infertility diagnoses. The lack of difference in prevalence of male factor infertility between groups was limited by our inability to confirm semen analysis results of male partners of all subjects. Furthermore, the race and ethnicity of the male partners were not obtained, and we could not assess whether male partner racial and ethnic differences impacted rates of infertility.