The whole syphilis/congenital syphilis and going on to remission, not all kids dying etc thing is interesting and complicated.
I am a medical-type person and thought I knew quite a lot about it, but what the chap on the programme said conflicts with what several pathologists/ GUM consultants have recently told me. I asked them because of my GG grandmother having a child who was certified as dying from congenital syphilis, in between other children who lived, and herself living until 77.
It has piqued my interest and I will do further research, but as have many family crises currently on-going, this will not be for a few weeks. But I will post here what I find, if anything.
Just remember, syphilis was by no means the only reason for many infant deaths - rhesus incompatibility would be another, but there are many many other causes for this. So we will not all have this explanation!