Dec 23, 2018
A number of scientists have argued that these miscarriages are not simply the failure of an embryo to develop. Instead, the mother's body may be using chemical cues to asses offspring quality and spontaneously abort embryos that show signs of genetic abnormalities. Miscarriages are a source of great psychological suffering, but they are favored by natural selection because they can reduce nine months of investment to a month or less for embryos that are unlikely to survive or reproduce on their own.
Carl Zimmer, Making Sense of Life