I do remember that was the case in the 70’s when I lived in Texas while serving in the Air Force. But I thought the law had changed. I could be wrong though.
Just a side note. At that time if the husband came home and found his wife in bed with someone else and he killed them he would most likely be acquitted of charges because it was a crime of passion. Women however were not allowed to use the same defense as him. This was changed before I left the state in 78.
Speaking as a Texas lawyer with an interest in family law, I assure you that you are mistaken. The presumption of marital paternity has always been rebuttable upon sufficient evidence.
So unless you can provide direct evidence (i.e. something beyond mere speculation) that these illegal abortions would suddenly constitute major risks, then I don’t think your argument holds water.
With much less certainty. Blood typing was available, of course, and that helped. But mostly it boiled down to testimony about who was cheating with whom and when, who the kid looked like, etc. DNA is the be-all and end-all of the dispute these days, but it was a lot messier back then.