ABO O gene frequency increase in the US might be causing increased maternal mortality.

Maternal mortality rate has increased in the United States over the past 30 years from 16 deaths per 100,000 births to 28 deaths per 100,000 births while the rest of the world is experiencing declining rates. Increasing obesity and c-section rates in the US have been cited as contributing factors needing remediation, and because of the two to three fold difference in maternal mortality rates in non-Hispanic black women compared to white women, inequality and implicit racial bias has been targeted as well for remediation. Using an epidemiologic approach, a hypothesis here brought to bear is that US immigration policy changes over the past 50 years have brought changes in the gene pool that have caused increasing obstetric hemorrhage and other causes of maternal death. ABO gene frequencies have changed in the US during this time such that ABO O, a gene associated with hemorrhage and mortality in pregnancy, has increased in frequency in the US thus increasing population maternal mortality rate. Using mendelian randomization logic, noting the increase in ABO O gene in the US population over the past 30 years and the association of ABO O gene with both hemorrhage and lower longevity, the increase in frequency of the ABO O gene in the past 30 years in the US population might be causative of an increase in maternal mortality rate. Consequences of this hypothesis would include recognition of the role of ABO gene and thus ABO blood group in prediction of risk of obstetric hemorrhage. Thus those at risk on this basis would be under high surveillance and would have medications and treatment strategies readily available. While research on ABO gene and pregnancy has been done, much of the research is being done in countries other than the US, and given the increasing mortality in the US as well as the role that ABO gene may have in that, further research needs to be done in US populations to quantify risk for all adverse events in pregnancy related to ABO blood type including hemorrhage as well as inter-related causes including pre-eclampsia, cardiovascular disease, thromboembolic disease and infection.