Changes in sex composition of births across regions and subgroups in India from an analysis of birth histories from National Family Health Surveys

India has consistently had one of the highest birth sex ratios (i.e., most males per female) globally. This analysis seeks to describe the sex composition of live births over the past decades among subgroups of the Indian population considering ongoing efforts to mitigate sex selection practices. Distribution of sex from the birth history data from three cross-sectional rounds of India's National Family Health Survey (2005-06, 2015-16, 2019-21) were used. We describe changes in the sex composition of live births across time through different phases of the PreNatal Diagnostics Technique Act by place of residence, caste, education, and wealth. Multilevel random effects logit regression models were used to estimate odds ratios and adjusted estimates for the different periods. The proportion of male births remained stable across the 1980s and early 1990s for the country overall, followed by a decrease until 2000 and plateauing subsequently. This trend was not uniform, with the Northern region peaking in 2000 before falling to lower levels, while the Southern region peaked in the 80s and trending downward in the 1990s. Spatial analysis and regression models showed a decrease in the proportion of male births during 2004-11 time period in the Northern region compared to 1995-2003 time period with the higher wealth quintiles decreasing the most. The proportion of male births elicited through birth histories in India has trended downward influenced by demographic changes but the decrease was not uniform across regions and sub-groups, possibly influenced by antenatal sex selection practices.