The odds are stacked against sperm. Most of the 150 million cells released when a man and woman have sex fail to make it through the vagina.
Those that do must dodge dead ends and lethal white blood cells to make it to the fallopian tubes. Just 10 or so will – and only one can fertilise the egg.
It’s a perilous journey that requires a lot of luck and an impressive swimming technique, the details of which have eluded scientists, until now.
But now a new study reveals how successful sperm are able to propel themselves to the egg, and it’s all down to rhythm.
The head and tail movements of sperm follow patterns similar to fields that form around magnets, researchers found.
Dr Hermes Gadelha, a lecturer in applied mathematics at the University of York, and his team measured the beat of the cells’ tail as they swam.
The results showed that a simple mathematical formula could explain the rhythm.
Dr Gadelha described the successful fertilisation of an egg by a sperm as “one of the greatest miracles ever” in an interview with the BBC.
It’s hoped that by revealing exactly how individual sperm swim, the researchers will be able to predict how large numbers move.
Revealing why some sperm succeed where others fail could help treat male infertility, according to the researchers.
The NHS reports that about one in seven couples in the UK, approximately 3.5 million people, have difficulties conceiving.