Sleepless nights, regular feeds, endless crying…Taking care of a new-born baby can be a stressfully challenging time for any new mother. Therefore, any woman could be forgiven for losing her sex drive in the short-term whilst trying to battle a constant feeling tiredness on top of feeling worried about still being appealing in the eyes of their partner following post-pregnancy weight gain. However and perhaps surprisingly, it is not just mothers who have their libido impacted during the initial stages of parenthood, with a new study suggesting that fathers are also quite prone to losing their sex drive. Researchers at Notre Dame University conducted the largest study of its kind, analysing how the biology of 400 new fathers in the Philippines altered following the arrival of their children. Lead researcher Dr Lee Gettler, found that the men participating in the study experienced a decrease of testosterone by about a third within the first year after the birth of their child. In addition, hands-on dads who spend at least three hours each day with their child typically see a further decline of an estimated 20%. Those behind the study claim “the sensitising effect” is created by both the psychological and cultural impulse to protect a new-born baby and would have a similar result on adoptive fathers; making them more caring and less of an aggressive nature. Past studies have demonstrated evidence that suggests men with high levels of testosterone tend to have less sympathy in general and less urgency to react when a baby is crying. What the findings mean for new mums is perhaps a lesser risk of their partner straying after the birth of their child, and women should have less concern about upsetting him if she does not want to have sex often in the initial first year. Women are simply programmed to prioritise taking care of their children, with sex drive put on the backburner so to speak. “If you think about fathers in other mammalian species, they don't really help taking care of the children,” commented Dr Gettler. “So it seems that natural selection has stepped up men's hormone system to respond to the needs of their offspring.”