This is what Wikipedia says about her views on abortion, for what it’s worth. The statements they quote make it sound like she opposed it mostly. Perhaps she had an “evolving” position on it? I would have to assume that when she founded Planned Parenthood, abortion was illegal so she probably wasn’t openly advocating for it. I don’t know if PP would’ve been facilitating “back alley” abortions at that time or not.
http://en.wikipedia.org/wiki/Margaret_Sanger
Abortion
Sanger’s family planning advocacy always focused on contraception, rather than abortion.[95][note 10] It was not until the mid 1960s, after Sanger’s death, that the reproductive rights movement expanded its scope to include abortion rights as well as contraception.[note 11] Sanger was opposed to abortions, both because they were dangerous for the mother, and because she believed that life should not be terminated after conception. In her book Woman and the New Race, she wrote, “while there are cases where even the law recognizes an abortion as justifiable if recommended by a physician, I assert that the hundreds of thousands of abortions performed in America each year are a disgrace to civilization.”[98]
Historian Rodger Streitmatter concluded that Sanger’s opposition to abortion stemmed from concerns for the dangers to the mother, rather than moral concerns.[99] However, in her 1938 autobiography, Sanger noted that her opposition to abortion was based on the taking of life: “[In 1916] we explained what contraception was; that abortion was the wrong way no matter how early it was performed it was taking life; that contraception was the better way, the safer way — it took a little time, a little trouble, but was well worth while in the long run, because life had not yet begun.”[100] And in her book Family Limitation, Sanger wrote that “no one can doubt that there are times when an abortion is justifiable but they will become unnecessary when care is taken to prevent conception. This is the only cure for abortions.”[101]