Also I think you are confused about these terms in English, where Old Church Slavonic == Старославянский язык Church Slavonic == Церковнославя́нский язы́к
>The Novgorod birchbark letters that were excavated over the 20th century attest some early East Slavic, noticeably different from the Old Church Slavonic language
That is correct, however what I wrote was completelly different: "All the survived early written texts of Rus are in Old Church Slavonic."
Besides, they were neither early East Slavonic or even classified as modern East Slavic and they are not directly related to Russian as well. Many of those Slavic can be classified as early Western Slavic at best.
>No, беременна is a native Slavic word and not a Swedish borrowing It seems, that I was wrong in this one(as pregnancy in most of Slavic languages use different word, but I did not search further, where Bulgarians use similar word for pregnancy). Sadly, that also means that Old Church Slavonic replaced everything else.