Sanger was in favor of whatever it took to get rid of those she considered to be undesirables. She focused on birth control because that's what she could sell to foundations who pass out grant money and who were far from ready to start sanctioning and supporting abortion at the time she got her start. If she could have gotten mass deportation as a solution, she would have done it. If she could have gotten ovens and Zyklon B, she'd have done that.
There's plenty of proof around to show that Sanger didn't care how those she considered undesirable were shed as long as they were gone in a few generations. Those who are apologists for the Grand Dame of mass murder have generated a large mass of revisionist history in an effort to hide the facts and portray Sanger as a Saint, but it doesn't wash. It's just another example of fascist propaganda being spread to dull the minds of the masses and feed to the captive minds in government schools.
Sanger was a disciple of Gaulton, Gaulton was the father of Eugenics, Eugenics stated, "The laws of nature require the obliteration of the unfit and human life is valuable only when it is of service to the community or race". Clearly, that's not birth control, that's obliteration of human life when it isn't valuable to the community or race. Gaulton, Grant, and others heading the Eugenics movement, chose Sanger as their spokesperson specifically because she was advocating abortion as a means of population control and birth control as a means for the "better races" to limit themselves to a number of children "appropriate to their circumstance".
Sanger advocated, approved of, and suggested, various ways to implement the mass murder of blacks and other races she considered too primitive to continue to exist. The only misunderstanding about Sanger that exists is the misunderstanding on the part of those who are willing to swallow the lie that she was a woman with good intentions at any point in her adult life. She used exactly the same vocabulary to justify "birth control" that Eugenics writers and slave holders had used to justify slavery and total control of the breeding of slaves. Her response to those who questioned abortion was always that while mandatory sterilization was preferred, people were ignorant and would not approve of it in many states. Only when sufficiently wealthy immigrants began to object to her including them in her list of undesirables did she begin to use "quality of life" arguments to justify birth control among those groups rather than continuing to advocate forced sterilization for them. She advocated that the poor and illiterate, among others, be put into camps where they would be sterilized prior to being used a labor resource for the state. That's not the view of sweet little lady with the best of intentions. Nor would a sweet little advocate of birth control and nothing else brag about their commitment to Eugenics goals of race purification in their own autobiography in the same chapter that she suggested making it illegal for doctors to treat children of undesirable races as a means to reduce the infant survival rate among such races.