Week 24: your baby is the size of a porcupinefish

Your fetus reaches about 30 cm this week, the length of a porcupinefish, also called a porcupine pufferfish. Relaxed, it is an ordinary-looking fish. Threatened, it becomes a spiky beach ball.

When alarmed, it gulps water and inflates its body several times over, making all its spines stand straight out. A predator is suddenly faced with a spherical pincushion far too large and painful to swallow.

As a backup, many pufferfish also carry tetrodotoxin, one of the most potent natural poisons known. Between the spines and the toxin, very few animals make the mistake of trying to eat one twice.

Meanwhile, inside you

Your fetus this week reaches an important milestone: viability. Their lungs are beginning to make surfactant, the substance that lets air sacs stay open, which means that with intensive care, survival outside the womb is now possible.