there's no hard and fast rule to morning sickness.. however if she has the heartburn feeling, ask her to tell her gynae next appt and see if can get meds to ease the discomfort.
some lucky women will have their MS end at 13 weeks.. end of first trimester.. the unlucky ones could have it throughout the whole pregnancy. MS usually involves nausea and vomiting..
maybe let her choose what she wants to eat.. =) my this pregnancy i've to eat all my husband's favourite food.. it seems like the baby wants to be like daddy. all my favourite food is yuck now. lol.. pregnancy is a funny thing.. but it can also be one of the most beautiful thing that can happen to a woman.