This is terribly superficial science based purely on external appearances. It does not even acknowledge the vastly different functions of developing features of completely different animals. Furthermore, in the 1950's it was proven that a woman's fertilized egg is a complete human being. Only time and nutrition are required for it to grow larger. From the moment of conception, a pregnant woman's body is two bodies, not one.
Gill slits form gills in fish.
In humans, they are merely folds forming various glands and facial features. The yolk sac contains food for a reptile, while for a human it has a radically different function. Yet, the developing baby may have a different blood type than its mother, so cannot use her blood. The simplest engineering answer would be to provide a temporary alternative supply. 3 A woman does not have an abortion because she believes in evolution, but how much easier it is to justify killing a developing baby which is just going through some stage of comparative embryology or is just a blob of matter.