I think that abortion is the elephant in the room here. A history of previous abortion is as damaging to a pregnancy as smoking, causing premature births and miscarriages. Smoking can be stopped, but a woman cannot go into the past and undo her previous decision to get pregnant despite having no intention to have the baby alive. The damage of abortion is permanent. And black women are especially targeted by the abortion industry.
Your abortion theory might be true. Maternal and infant deaths have a pattern.
1) Young teens to young to bear children
2) Women of child bearing age 18-35 wWo have a bad lifestyle.
3) Women over 35, some over 40, who waited too long to bear their first child. Most likely some of these career women had abortions. It would be difficult to find the data and prove it one way or the other.
Women over 35 who have given birth to 5 or 6 children already rarely have a problem with the last one. It is that first full term pregnancy and first baby and first post-delivery experience of the women who waited too long that is a problem area.
Do you have sources for the abortion/later pregnancy complications connection?