Editing Infant mortality (section)

====Male sex favoritism====
Historically, males have had higher infant mortality rates than females, with the difference being dependent on environmental, social, and economic conditions. More specifically, males are biologically more vulnerable to infections and conditions associated with prematurity and development. Before 1970, the reasons for male infant mortality were infections and chronic degenerative diseases. However, since 1970, male sex favoritism in certain cultures has led to a decrease in the infant mortality gap between males and females. Also, medical advances have resulted in a greater effect on the survival rate of male infants than female infants, due to the initial high infant mortality rate of males.<ref name="Dreven">{{Cite journal |vauthors=Drevenstedt GL, Crimmins EM, Vasunilashorn S, Finch CE |date=April 2008 |title=The rise and fall of excess male infant mortality |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=105 |issue=13 |pages=5016–21 |bibcode=2008PNAS..105.5016D |doi=10.1073/pnas.0800221105 |pmc=2278210 |pmid=18362357 |doi-access=free }}</ref>

Genetic components result in newborn females being at a biological advantage when it comes to surviving their first birthday, versus newborn males, who have lower chances of surviving infancy. As infant mortality rates decreased globally, the gender ratios changed from males being at a biological disadvantage to females facing a societal disadvantage.<ref name="Dreven" /> Some developing nations have social and cultural patterns that favor boys over girls for their future earning potential. A country's ethnic composition, [[Monoethnicity|homogeneous]] or [[Polyethnicity|heterogeneous]], can explain social attitudes and practices. Heterogeneous levels are a strong predictor of infant mortality.<ref name="Fuse" />{{Verify source|date=July 2023}}