Hello Welcome to Health Care Magic. No one can predict from now that your wife will have normal delivery or not. she is short stature but her pelvis outlet may have good space to deliver baby. there are many other factors like weight and head circumference of baby at the time of delivery, position of baby in womb, any fetal distress or not. there are many factor even more than this which is totally out of control so leave thinking about it. still long way to go. back pain is very common symptom during pregnancy. but any alarming signs like contractions or vaginal discharge should not accompany it. taking rest is necessary. left lateral position will give good circulation to fetus. tablet paracetamol once a day only for few days is not harmful.paracetamol is totally harmless but donot use it frequently. its very common over the counter drug. Don t worry much. stay calm. Best wishes