You are correct, perhaps I missed some signs. I may have missed the loss
of
the mucus plug, and I did have back ache. In any case Naomi was 7lbs and
apparently 5 weeks early, but I didn't know my dates and she was dated by
the first scan which was not until about 26weeks.

dating is very inaccurate at 26 weeks, I suspect she was early, but maybe 2
or 3 weeks not 5