FruitlessFetusSign upYour fetus now weighs about a kilogram, the weight of a female greater bilby. From here on, most of our comparisons switch from length to weight, because your baby is starting to get properly heavy. The bilby is a rabbit-eared, silky-furred marsupial from the Australian deserts, and it is enchanting.
Those huge ears are radiators, shedding heat in the desert, and they give the bilby extraordinary hearing to locate insects underground. It is a tireless digger, building spiralling burrows up to three metres long, and its abandoned tunnels shelter dozens of other desert species, which makes it a keystone engineer of its ecosystem.
Like all marsupials it raises its young in a pouch, but the bilby's pouch opens backward, toward the tail, so it does not fill with sand while she burrows. In Australia the bilby has partly replaced the rabbit as an Easter mascot, with chocolate bilbies sold to raise money for the real thing, which is threatened.
Meanwhile, inside you
Your fetus this week can blink, and their eyes can now detect light and even respond to a bright light shone on your belly. They are also putting on the fat that will fill out those newborn cheeks.