Bone Marrow Transplants: When Race Is an Issue
Compared to organ transplants, bone marrow donations need to be even more genetically similar to their recipients. Though there are exceptions, the vast majority of successful matches take place between donors and patients of the same ethnic background. Since all the immune system’s cells come from bone marrow, a transplant essentially introduces a new immune system to a person. Without genetic similarity between the donor and the patient, the new white blood cells will attack the host body. In an organ transplant, the body can reject the organ, but with marrow, the new immune system can reject the whole body.
http://content.time.com/time/health/article/0,8599,1993074,00.html

Differing Intergenerational Birth Weights among the Descendants of US-born and Foreign-born Whites and African Americans in Illinois
Abstract
The authors analyzed Illinois vital records to determine the intergenerational birth weight patterns among the descendants of US-born and foreign-born White and African-American women. Among the descendants of the generation 1 US-born White women (n = 91,061), generation 3 females had a birth weight 65 g more than that of their generation 2 mothers (p < 0.0001); generation 3 infants had a 10% lower moderately low birth weight (1,500–2,499 g) rate than did their generation 2 mothers: 5.0% versus 5.5% percent, respectively (relative risk = 0.9, 95% confidence interval: 0.9, 0.9). Among the descendants of generation 1 European-born White women (n = 3,339), generation 3 females had a birth weight 45 g more than that of their generation 2 mothers (p < 0.0001). Among the descendants of generation 1 US-born African-American women (n = 31,699), generation 3 females had a birth weight 17 g more than that of their generation 2 mothers (p < 0.001). Among the descendants of generation 1 African/Caribbean-born women (n = 104), generation 3 females had a birth weight 57 g less than that of their generation 2 mothers; generation 3 females had a 40% greater moderately low birth weight rate than did their generation 2 mothers: 9.6% percent versus 6.7% percent (relative risk = 1.4, 95% confidence interval: 0.6, 3.6). Maternal age and marital status did not account for the birth weight trends. The authors conclude that the expected intergenerational rise in birth weight does not occur among the direct female descendants of foreign-born African-American women.
https://academic.oup.com/aje/article/155/3/210/63367

The Low Sex Ratio in Negro Births and Its Probable Explanation
https://www.jstor.org/stable/1537084?seq=1#page_scan_tab_contents

Sex Ratio at Birth and Racial Differences: Why Do Black Women Give Birth to More Females Than NonBlack Women
The two important questions that this paper will attempt to answer are: (1) why is it that
regardless of race/ethnicity or geographic location, the sex ratio data at birth show more males
than females?; and (2) Why is it that regardless of geographic location compared to other
racial/ethnic groups, Black women or Women of sub-Saharan Black African descent tend to
give birth to more females? Or to put this question the other way around, compared to Black
women, why do non-Black women give birth to more males?
https://www.ajol.info/index.php/ajrh/article/download/55641/44113