<Table> <Tr> <Td> </Td> <Td> This article's factual accuracy is disputed . Relevant discussion may be found on the talk page . Please help to ensure that disputed statements are reliably sourced . (December 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article's factual accuracy is disputed . Relevant discussion may be found on the talk page . Please help to ensure that disputed statements are reliably sourced . (December 2017) (Learn how and when to remove this template message) </Td> </Tr> <P> A baby's sex is determined at the time of conception . When the baby is conceived, a chromosome from the sperm cell, either X or Y, fuses with the X chromosome in the egg cell, determining whether the baby will be female (XX) or male (XY). To be female, one needs to be (XX), whereas to be a male, (XY) is needed . It is the Y chromosome that is essential for the development of the male reproductive organs, and with no Y chromosome, an embryo will develop into a female . This is because of the presence of the sex determining region of the Y chromosome, also known as the SRY gene . </P> <P> A fetus doesn't develop its external sexual organs until the second month of pregnancy--seven weeks after conception . The fetus appears to be sexually indifferent, looking neither like a male or a female . Over the next five weeks, the fetus begins producing hormones that cause its sex organs to grow into either male or female organs . This process is called sexual differentiation . The precursor of the internal female sex organs is called the Müllerian system . </P>

When does a baby turn male or female