Normally not more than a 40 weeks, if you wants without any harm to your baby, then you must focused on your diet, diet should be organic and you can also exercise on your daily basis.
Use this pregnancy week calculator ,if you wants to track your pregnancy week by week.
That would make the person at least 44 weeks when the baby was born - this is highly unusual and dangerous but not totally impossible.
I am guessing there is doubt here about the paternity of said child and I would be highly doubtful based on these dates that you could be the father BUT it's not impossible. Most medical providers wont allow a woman to go beyond 42 weeks for medical reasons, as another poster has said, the placenta has begun to degrade by then and therefore puts the baby and the mother at risk. However the mother may have refused treatment to induce labour - that is her right. I think in this case a dna test would be the most reliable method to settle the matter.
You must focused on eating organic diet that is good for your baby..!
Here you track pregnancy, also about the pregnancy week by week.