Temperature fluctuations caused by climate change may be affecting the male-to-female birth ratio, say researchers at the M&K Health Institute in Hyogo, Japan. This is based on a study they conducted showing that male birth rates are slightly higher in areas with warming temperatures, and fewer boys are born in areas affected by severe environmental changes like droughts or wildfires.
Overall, the sex ratio in humans is believed to be equal at conception, but more female embryos die during gestation, resulting in slightly more male births. The male-to-female birth ratio is normally between 103 and 106 males to 100 females.
The Japanese researchers say fluctuations in environmental factors like temperature aren’t expected to have long-lasting effects on birth ratio, nor are they expected to be uniform worldwide. But these effects are significant, they say, because newborn sex ratio is an important indicator of reproductive health.
Sourced from: Fertility and Sterility