Everything a mother does during and before pregnancy typically has a huge effect on a baby’s future. However, factors surrounding the father in the moments before conception have been shown to have an impact on the likelihood of their offspring becoming obese.

In a study published by Nature Medicine, the research found that men who spend time in low-temperature conditions produce more brown adipose tissue in their sperm. This is more commonly known as brown fat- a substance which speeds up the burning of excess energy stored in the body. Previous research has shown that those with more brown fat in the body have a lower risk of becoming obese or overweight.

To reach this conclusion, scientists from Zurich analysed 8,400 adults. They found that those who were conceived during the winter time had higher levels of brown fat compared to those who were conceived in summer.

This study was then performed using mice. As with humans, male mice kept in cool conditions produced offspring with higher brown fat levels. The temperature of female mice around conception did not make a difference to the brown fat levels. When placed on a high-fat diet, the mice with more brown fat gained less weight than those with lower levels.

It has also been suggested that the connection between warmer temperatures and less brown fat could explain why obesity rates in the US have never been higher. Over the last few decades, the average indoor temperature in the US has increased and this could be one of the factors contributing to the surge in obesity.