Divergences in sex ratio at birth in US Census Regions due to racial factors: chronic stress and female foeticide

Abstract

ObjectivesThe sex ratio of live births (males/total [M/T]) approximates 0.515. Many factors reduce M/T, and these include stress. Antenatal sexing is used for female foeticide in the setting of male offspring preference. Regional differences and latitude gradients in M/T also occur. This study analysed M/T in the US by Census Regions. Study designThis was an ecological study. MethodsLive births by sex, Census region, state and mother's race were obtained from CDC Wonder (2007–2020). ResultsThere were 55,453,437 births (M/T 0.5116, 95% confidence interval: 0.5115–0.5118). M/T was Black/African American < Indian/Alaska Native American < White < Asian (P<<0.0001). M/T was significantly lowest in South and highest in West. The South had the lowest proportion of Asian/Pacific Islander births (3.9%) and the highest proportion of Black/African American (21.9%). West has the highest proportion of Asian/Pacific Islander (11.2%) and the lowest proportion of Black/African American births (5.3%). In Asian/Pacific Islander births, M/T significantly rose to third order and fell to sixth order births, unlike the other races that showed a decline from the first order. ConclusionsAsian M/T may be elevated because of male offspring preference and selective female foeticide. M/T may be depressed in Black and American Indian/Alaskan births due to chronic stress, as race remains the most important factor associated with wealth inequality in the United States. The lower M/T of these two races when compared with White equates to a constant loss of 4.13 and 2.55/1000 male births. The higher Asian M implies a chronic loss of 3.78 females per 1000 births. Both have public health implications.