I Am Looking For A Book Series I Read When I Was Younger. Can Anyone Help Please!

So, there was a book series that I read when I was younger and I want to find it again. It was a book series that went followed a family across decades. The front of the books had family trees laid out. I remember one book has a scene where the mother gave birth to a daughter in or near a barn around Christmas. I know it's not much to go on, but if anyone can help that would be great. For some reason I wanted to say that the series title had something to do with decades.