I think the premise of a young girl finding out she is pregnant and trying to hide it s plausible but they made it unbelievable in the way they portrayed it. The religious people in these shows are always "over the top" and seem to only use the old testament to harbor ill feelings toward others.
I thought that having Mrs. Olson think Laura had a baby was funny at first, but didn't make sense since that would have been hard to hide from most people being so active in the community and Willie as the Dad...he looked 10!
I also wondered what happened too all the other Ingall's children...they showed Mary and Carrie in the beginning but then they disappear. Laura is in Carrie's bed at night watching the baby, they aren't around when they get ready to go to Doc Baker's before school, Mary isn't in bed when she comes home late and she gets sent to the loft for punishment...those are big holes in such a little house...distracting for me watching because it was such a glaring omission.