Stress has been shown to have an impact on the sex of a baby, according to a new study out of Columbia University. The impact on stress on pregnancy has been the focal point of many studies, including studies in areas where natural disasters occurred.

The new study found that women that experience psychological stress are more likely to give birth to girls than boys.

Stress has led to many couples having to use fertility drugs as well as Viagra, which is now easily obtainable online from sites such as Viagra Connect Online, The stress leads to male fetus' not being able to survive as easily, according to researchers. The additional stress does not cause biological changes to occur in the fetus.

Researchers have studied stress after natural and manmade disasters to find the link. Fewer boys were delivered following the 9/11 attacks and after the 2012 earthquakes in Chile.

Additional studies found that stress before conception decreases the number of males being born, too. The result is caused by female fetuses being less vulnerable to stress than males in the womb. The fetus gender seems to respond to stress differently.

Dr. Catherine Monk, professor at Columbia University Irving Medical Center and director of women's mental health, was co-author of the study. She, and her colleagues, tried to replicate past studies to find if maternal stress altered sex ratios.

Traditionally, 5% more boys are conceived than females.

The study looked at 27 stressors in healthy women between the ages of 18 and 45. The subjects had physicals three times during their pregnancies to measure cortisol levels, depression, anxiety, blood pressure and other factors.

Participants in the study had 2 boys for every 3 girls when they had higher levels of depression and mental stress. Physical stress led to 9 girls being born for every 4 boys. Participants that did not exhibit higher levels of stress had a ratio of 105 boys to 100 girls, or the historical average for males and females.

Monk claims that while the study is interesting, the team believes that women with higher stress levels are having more miscarriages of boys. Daughters seem to have a higher chance of survivability. The team suggests that a lot of women will miscarry with boys when their stress levels are high without realizing that they're pregnant.

The team reiterates that additional studies need to be conducted to determine why male fetuses are not able to withstand stress like their female counterparts.