New data has indicated that in rats, "male" hormones drive the decision to become a male during a window of time before male genitalia develop, and that blocking "male" hormones during this time caused male genitalia birth defects.

These defects were associated with a decreased ano-genital distance, leading to the suggestion that measuring human neonatal AGD could provide a noninvasive method to predict those at risk of developing male genitalia birth defects.

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