A happy foetus is a smiling foetus!
A professor at London's Create Health Clinic has poineered a new type of ultrasound scan which gives us, for the first time, pictures of foetuses as young as twelve weeks walking, yawning, moving their arms and legs, and at 18 weeks, opening their eyes, and even smiling at 26 weeks.

The new technique gives much more detailed pictures than conventional ultrasound, and according to Professor Stuart Campbell,

"This is a new science for understanding and mapping out the behaviour of the baby. Maybe in the future it will help us understand and diagnose genetic disease, maybe even conditions like cerebral palsy which puzzles the medical profession as to why it occurs."
He's compiled a book of the images, called Watch Me Grow, and provides 10 beautiful sample images linked within the original article from the BBC. hattip imrdkl