You forgot to mention blacks were valued at 10x the dollar amount as white indentured servants, so there were fewer blacks under servitude than whites. Frequently owners would breed 10 white women to one black slave.
Sorry, don't buy it. I don't think children of white indentured women were born chattel. Children generally inherited their mother's legal status.
In this country it was the black slave owners who were also slave breeders. Whites were not the breeders.