4D Ultrasound

We'll never know whether this particular in-utero yawn was due to a touch of boredom (after 30 weeks of staring at the walls) or just plain fatigue from the strain of growing everything from arms to eyelashes.

Thanks to the amazing 4D ultrasound technology now available, footage like this allows us to see exactly what the average foetus gets up to before they make their way into the world. Common in-womb activities include yawning, blinking, smiling, urinating, ear-pulling and even wrestling with their co-twin.

Apart from giving parents a literal sneak preview of their precious bundle, ultrasound video monitoring such things as yawning frequency could soon be used by doctors as a vital foetal developmental indicator.

Scientists studying the phenomenon at Durham and Lancaster Universities in the UK have found yawning rates lessen with gestational age. And while they are yet to determine exactly why unborn babies yawn, their findings show movement may be related to the maturation of their central nervous systems.

Whatever it shows, it's pretty damn cute.