FruitlessFetusSign upHalfway there. Your fetus has just grown past the length of a hero shrew, a smoky-grey, invertebrate-eating shrew from the Congo Basin whose body runs about 12 to 15 cm. It looks utterly ordinary and hides the most bizarre backbone of any mammal on Earth, shared only with its close relative, Thor's hero shrew.
Its lower vertebrae are covered in interlocking bony tubercles that fit together like the teeth of a zipper, turning its spine into a single flexible column of extraordinary strength, four to five times sturdier for its size than any other mammal's.
Local Mangbetu accounts, later witnessed by an expedition team, describe a full-grown man standing on the animal's back and stepping off while the shrew walked away unharmed. Nobody is entirely sure why it needs a spine that strong.
Meanwhile, inside you
Your fetus this week is at the traditional halfway point of pregnancy. If you have an anatomy scan around now, it is why: enough has developed to check the major organs, and there is still room to see them clearly.