FOR men, simply wanting to have a child could be enough to help it happen. It seems wannabe fathers adjust their testosterone levels to make conception more likely.
Katharina Hirschenhauser, an expert in sex hormones, and her team at the Institute of Applied Psychology in Lisbon set out to see if there was any link between men鈥檚 testosterone levels and their sexual behaviour. They asked 27 volunteers to measure the testosterone in their saliva every morning for 90 days. Over the same period, the men also recorded their sex lives in intimate detail, documenting the 鈥渋ntensity鈥� of each encounter, whether with their regular partner or not.
All the men had different patterns of testosterone peaks and troughs over the period. But in men trying for a baby, peaks in testosterone levels coincided far more often with periods of intense sexual activity (Hormones and Behavior, vol 42, p 172).
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Hirschenhauser says the finding shows men can subconsciously influence their hormone levels. 鈥淢ales can be responsive to their partners, but only if they want to be,鈥� she says.
Jim Pfaus, an expert in sexual neurobiology at Concordia University in Montreal, says this could overturn a common and uncharitable belief about men. 鈥淲e tend to think of the little brain being disconnected from the big brain,鈥� he says.
Coordinating sexual activity with peaks in testosterone makes sense for men who want to be fathers. Rises in testosterone also trigger a hormonal pathway that increases sperm production, making conception more likely. 鈥淚n short, you鈥檙e less likely to shoot blanks,鈥� says Pfaus.
There may be more to it than wannabe fathers simply having more sex when their testosterone is high, adds Pfaus. It is well known that women are more receptive to sex around the time of ovulation. Previous studies have also shown that women who live together synchronise their periods 鈥� probably through pheromonal cues. Perhaps, says Pfaus, men who want a baby respond directly to their partner鈥檚 pheromones and synchronise their testosterone peaks with the mid point of their partner鈥檚 cycle, when they are most likely to conceive.