THE TIMING of a woman's orgasm may affect the number of sperm that are 'sucked' into her womb, say researchers from the University of Manchester. After sexual intercourse, many sperm are discarded in the 'flowback', globules of fluid expelled from the vagina. If a woman climaxes up to a minute before her partner, or has no orgasm at all, more sperm are ejected from the vagina. But if a woman's climax coincides with, or follows, the man's then she retains larger numbers of sperm. The female orgasm, a report in New Scientist concludes, is a 'virtuoso muscular performance' aimed at sucking sperm towards the womb.