FruitlessFetusSign upYour due date. Your fetus now weighs about 3.5 kg and measures around 51 cm, roughly a very heavy male kākāpō: the world's heaviest parrot, flightless, nocturnal, and one of the rarest birds alive.
The kākāpō is a very round, moss-scented parrot that cannot fly but climbs trees enthusiastically, booming through the New Zealand night from a hollowed-out bowl in the earth to call in mates. Kākāpō are thought to live around sixty years, and perhaps as long as ninety, and they are so treasured that every single kākāpō on Earth has its own name.
Forty weeks ago we started with stardust, and the kākāpō is a fair place to finish: an animal that is unlikely, slow to arrive, and worth the wait. In their own earliest weeks your baby grew, and then reabsorbed, structures we share with our fish and amphibian relatives: pharyngeal arches, a tail. Development is not a rerun of evolution, but it is built from a very old toolkit.
Meanwhile, inside you
Only about 1 in 20 babies actually arrives on the due date, so do not be surprised if yours keeps you waiting. When they arrive, they will be the size of exactly one baby, which turns out to be the most remarkable animal of all.