Part of Speech- Noun

Definition- a medical condition in which the ability of the blood to clot is severely reduced, causing the sufferer to bleed severely from even a slight injury. The condition is typically caused by a hereditary lack of a coagulation factor, most often factor VIII.

Source- Dictionary.com

“The Child Bearer” by Anne Sexton

In the poem, the speaker is using the word to describe being passed on like a genetic disease.