Technique is based on differences in movement of sperm with X chromosome and Y chromosome

A new sperm separation technique may one day allow prospective parents undergoing IVF to choose whether they have a boy or a girl before fertilisation takes place, researchers say.

Scientists in Japan have reported a new method which allows them to separate mouse sperm carrying an X chromosome from those carrying a Y chromosome, meaning that sperm can be selected based on whether they will result in female (XX) or male (XY) offspring when used to fertilise an egg.

Related: Sex selection is a false choice – our destiny is not defined by our genitalia | Ally Fogg