As stated elsewhere on Reader Rant
, during Margaret Sangers time, there were a lot more white poor Americans than there were black Americans. Sanger was pointing out to poor white Americans that having more children made you even poorer as children cost money to rear, clothe, and feed and having more children was a vicious circle that kept you poor.
Sanger may have belonged to the KKK but that's an entirely different issue. Was Margaret Sanger a racist? National Institute of Health