This forum ain't the place for all the old falsehoods about Sanger.
She absolutely did NOT have anything to do with "eugenics" as that term came to be used and applied, or with anything having anything to do with any "master race".
She isn't proof of anything the anti-choice brigade might want to say. Lies are told about her by the anti-choice brigade.
The reasons are two-fold, as were her own goals, which they oppose: women who enjoy their own sexuality without concern for right-wing "morality", and women who control their own reproductive destinies.
Martin Luther King himself praised Sanger when he accepted an award in her name from Planned Parenthood:
http://www.plannedparenthood.org/about-us/who-we-are/reverend-martin-luther-king-jr-4728.htm
... There is a striking kinship between our movement and Margaret Sanger's early efforts. She, like we, saw the horrifying conditions of ghetto life. Like we, she knew that all of society is poisoned by cancerous slums. Like we, she was a direct actionist a nonviolent resister. She was willing to accept scorn and abuse until the truth she saw was revealed to the millions. At the turn of the century she went into the slums and set up a birth control clinic, and for this deed she went to jail because she was violating an unjust law. Yet the years have justified her actions. She launched a movement which is obeying a higher law to preserve human life under humane conditions. Margaret Sanger had to commit what was then called a crime in order to enrich humanity, and today we honor her courage and vision; for without them there would have been no beginning. Our sure beginning in the struggle for equality by nonviolent direct action may not have been so resolute without the tradition established by Margaret Sanger and people like her. Negroes have no mere academic nor ordinary interest in family planning. They have a special and urgent concern. ...
I have just posted a thread about an event in Canadian feminist history that changed the course of Canadian history in general, by the foundation it provided for equality-seeking groups to press their cause. Women won a case againt discriminationin 1929, and 80 years later that case continued to be cited, in the Supreme Court decision on same-sex marriage.
As MLK acknowledged in 1966, this other women's battle, the struggle in the US for access to the means to plan their families, paralleled and directly benefited African-Americans' struggle for equality.