* The technology necessary to manufacture safe and effective intrauterine "copper T" contraceptive devices has been in place since ca. 3000 BCE in multiple parts of the world. And, while we have a decent understanding of how they work now, at the time that these devices came into widespread use in the 1970s, medical professionals and scientists had only a dim and conjectural understanding of how they worked. So far as I can discern, however, this innovation was never made in any pre-modern society (or at least, didn't enter widespread use). I thought I once saw an argument that this has been done in ancient Egypt, but have been unable to locate a confirming source for that assertion.
* The germ theory of disease was highly effective in dramatically reducing infectious disease deaths decades before there were any antibiotics or vaccines in widespread use, and well before we had a comprehensive understanding of leading infectious disease agents (i.e. bacteria, viruses, parasites and prions) and vectors. Yet, while treatments or a more particularized understanding of infectious diseases required access to advanced laboratory sciences, a highly distilled germ theory of disease framework that could be summed up in a couple of pages of text or a few minutes of oral tradition, which would be sufficient to reduce infectious disease mortality by perhaps 80% or more, could have been developed with pre-metal age ceramic tool making technologies in the Neolithic era and if they ever were, would have conferred immense selective fitness enhancing benefits.
We know this because the decline in infectious diseases in the modern era coincided with the widespread acknowledgment of the germ theory of disease and significantly preceded the development of vaccines and antibiotics, which also helped, but appeared only well after the germ theory was developed. Simple sanitation and quarantine concepts were more important than either of these medical treatments.
In point of fact, religious purity concepts and taboos, and crude quarantine concepts were kludges that benefited from similar concepts. For example, in areas with high infectious disease risks great religious diversity marked by purity taboos that varied from village to village and county sized areas to county sized areas evolved to prevent outbreaks in human populations from killing off everyone, because some of the many religions in any region would have the right taboos to survive the infectious disease threat de jure. Meanwhile, religious purity taboos were less central to religious practice and had greater geographic scope in areas where infectious disease risks were more mild.