"One in 100 patients will have a postpartum hemorrhage following childbirth," he said. "A much lower number will have a late-postpartum hemorrhage, and days or weeks later, will come back after heavy bleeding."
Weiss said hemorrhaging can be caused by any number of factors, including blood vessel spasms, underlying problems with clotting and placenta tissue left behind in the uterus after an abortion.
He said that in Reaves' case, she could have experienced two different kinds of hemorrhaging.
She could have either bled out through the vagina, or there might have been damage to the arteries that feed into the uterus, which could have caused blood to collect on the abdominal side of the uterus, he said.
"That could form a big bruise that could burst," he said. "Then all of a sudden, [the patient] would bleed briskly internally."