The heartbeats of a mother and her unborn foetus synchronise when she breathes rhythmically, researchers have said.
Scientists at the University of Aberdeen claim the connection paves the way for a new technique to detect development problems during pregnancy.
They said if this synchronisation did not happen it could signal something might be wrong. This, the researchers suggest, could allow early medical intervention.
Dr Marco Thiel, one of a team of physicists from the University of Aberdeen who worked on the study, said: "Pregnant mothers often report an awareness of a bond with their child. But until now there has been no hard evidence to suggest this bond is reflected in the interaction of their heartbeats. Our findings reveal that synchronisation between the heartbeat of a mother and foetus does actually occur - but only when the mother is breathing in a rhythmical fashion. The foetus can sense the rhythmical shift in the mother's heartbeat and adapts its own heartbeat accordingly."