CAMBRIDGE, Mass., Oct. 20 (UPI) -- The living arrangements of parents at the time a baby is conceived may play a role in determining its gender, research suggests.
A study by Dr. Karen Norberg at the National Bureau of Economic Research in Cambridge, Mass., found parents who were married or living together before conception were slightly more likely to have a boy than those who were not.
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The study was based on data from 86,436 births.
"This is the first evidence that household arrangements can affect the human sex ratio at birth, and could explain the fall in the proportion of male births in some developed countries over the past 30 years," Norberg wrote in the Royal Society's Biological Science journal.
