Scanning the online literature about this condition, I see nothing about how it endangers the life of the mother. Lacking other information, I’d surmise that they are leaning on the ambiguous “mental or psychological health” of the mother. The only danger is to the child, who may not survive the pregnancy or not survive long after birth. In other words, this woman probably just not want to carry this poor child to term, either not wishing to deal with delivering a stillborn baby or raising a disabled child for however long he or she survives. Very sad and very maddening that hardships like this have become a political issue.
They aren’t afraid the baby will die. They are afraid it will live and be damaged requiring they actually care for an imperfect child, cost money, and cause one of them to give up a career.