In a recent study, scientists discovered that there are genetic variations within the progesterone receptor gene which helps maintain pregnancy. Progesterone is a reproductive hormone that prevents pregnant women from going into labor too soon. With data from the 1000 Genomes Project, researchers were able to study the variations of the gene found in the East Asian, European, and African Ancestry populations. Scientists compared the genetic sequences in the progesterone receptor gene and found variations within the region of the gene that controls when the gene is turned on or off. East Asian populations were found to have a version of the gene that appeared to reduce the risk of premature birth compared to other populations where risk for premature birth is greater.
For more information, a short summary can be found on Medical Express. The complete research article, “Natural Selection has Differentiated the Progesterone Receptor among Human Populations” by Jingjing Li et al. is published in The American Journal of Human Genetics.