(CNN)Moms-to-be who undergo physical or mental stress during their pregnancies are less likely to have a boy and may also have a higher risk of preterm birth, according to a study published Monday.
A stressful pregnancy reduces the chances of having a boy, a study shows
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"The womb is an influential first home," said lead author Catherine Monk, director of women's mental health in OB/GYN at NewYork-Presbyterian/Columbia University Irving Medical Center.
Even though the sex of a baby is dictated at conception, pregnancies with boys are more vulnerable to mishap, she said.
"We do know that males are more vulnerable in utero, and presumably the stress in these women is of a long-standing nature," Monk said.
Nature typically assures there are an average of 105 boys born for every 100 female births; after all, males were more likely to die from accidents or fighting wild game.