Move over testosterone, another hormone is also vital for making boys – and it doesn’t come from the testes

Press/Media: Articles in 'The Conversation'


Often the first question parents are asked after the birth of their child is “congratulations, girl or boy?”. For parents of one in 2,000 to 4,000 births, however, there is not an easy answer. This is when the baby has “ambiguous” genitalia, where it is not clear which sex they belong to. In baby boys, this was long thought to be caused by problems linked to testosterone – as were more common disorders such as undescended testicles and malformed penises, which respectively occur in 9% and 1% of births.

But now it is clear that the reality is slightly different. According to new research in which I am a co-author, another hormone known as androsterone – which originates in the placenta and foetal adrenal gland – is also vital to the process that turns foetuses in boys. These insights have the potential to make a big difference to how we treat sexual disorders in male babies in future – and are also relevant to the whole debate about male and female identity.

Period14 Feb 2019

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