Pregravid hypertension may have different secondary sex ratio effects in different races in the United States

Abstract

BackgroundMales are born in excess of females and the ratio is expressed as M/F (male/female births=secondary sex ratio, also known as secondary sex ratio). This is expected to approximate 1.048. Racial M/F disparities are known. A recent study in China showed that pregravid systolic hypertension is higher in women who delivered a boy than in those who had a girl. This study was carried out in order to identify the effect of pregravid hypertension in the United States on M/F by race. MethodsMonthly male and female live births by race for the entire US along with the presence/absence of hypertension were obtained from the website of the Centers for Disease Control and Prevention for 2007–2015 for the four racial groups: American Indian or Alaska Native, Asian or Pacific Islander, Black or African American and White. ResultsThis study analysed 36,364,253 live births. For White births, mothers who had chronic hypertension were likelier to have male than female offspring when compared to non-hypertensives (p=0.003). Conversely, Black or African American mothers who had hypertension were less likely to have male than female offspring when compared to non-hypertensives (p=0.022). There were F differences for/F differences for the presence or absence of hypertension for the other two races or for the total. ConclusionsIt is possible that hypothesised innate interracial periconceptual hormonal differences may modulate M/F responses to hypertension in different races.