Maybe it is the location Ostrowo in Province of Posen, today Ostrów Wielkopolski in Poland. The parish registers are available starting 1741/1755/1756 for the catholic church (in Polish, Latin and German language) resp. starting 1775 for the protestantic church (in German language). They are available at familysearch.org (https://familysearch.org/search/search/library_catalog#searchType=catalog&filtered=true&fed=false&placeName=Germany,+Preu%C3%9Fen,+Posen,+Ostrowo+(KrSt.+Ostrowo)&catSearchType=place&uri=http%3A//catalog-search-api%3A8080/www-catalogapi-webservice/search%3Fquery%3Dsubject_id%3A418127%26count%3D50&subjectId=418127).
If I could be of further help (e.g. deciphering of German or Latin scripts) please contact me again.