welcome to HealthcareMagic
your wife has is due to increase of HcG during pregnancy
and it is a common symptom and is called hyperemesis gravidarum
.This vomiting may continue for 3-6 months of the pregnancy and then subside by itself.The treatment part consists of keeping hydration so she will have to take plenty of liquids and for the vomiting she has to take medicines like Doxylamine;Meclizine
which will help her to control the vomiting.I guess her doctor may have prescribed those medicines so give them and if there is need for dose adjustment please consult your doctor.