The slippery slope is a logical fallacy when used in a debate. However, with oppression it's a documented historical fact.
Forcing women to give birth is a relatively safe human rights violation. One can superimpose babyhood on a fetus and make it appear that one is merely protecting babies. But once the door is open to this human rights violation, the next one becomes easier because a precedent is set.
Not allowing women to give birth? A one-child policy? Segregation of sexes so reproduction can be controlled from the start? All part of the same set of human rights. All violated by forced birth.
For this, and many other reasons, I am writing a letter a day till we end forced birth by writing reproductive freedom into law.