Week 12: your baby is the size of a bee hummingbird

Your fetus is now the size of the smallest bird in the world, the bee hummingbird of Cuba, which measures about 5.7 cm from beak to tail. It weighs about as much as a US dime.

This bird is so small it is regularly mistaken for an insect. Its wings beat 80 to 200 times per second, its heart can race past 1,200 beats per minute, and it visits over a thousand flowers a day to fuel that engine.

The females build a nest about the size of a quarter and lay eggs the size of coffee beans. Everything about this animal is a study in how small a warm-blooded, high-energy body can get and still work.

Meanwhile, inside you

Your fetus this week has their own high-speed heart, beating roughly twice as fast as yours, and is now developed enough that many of their reflexes, like curling their fingers, are already switched on.