welcome to HCM,
This is common in pregnancy
called Emesis Gravidarum, If this is mild than it is patho-physiological condition and reduces gradually in 12 weeks.
Possible causes are Hormone changes of pregnancy, hypoglycemia
Increased sensitivity to odors.
She should take care of her diet specially in early morning like biscuits of glucose and possibly avoid non veg stuff for few weeks.
She can take fresh fruits and fiber in diet to avoid constipation
please also take adequate water.
I suggest to discuss about iron supplement may be with hold for some time till vomiting
subsides, and different iron salt may be tried to see which one is tolerated best.
Dried plums or Prunes may be taken in limited amounts.
There are good anti emetics which works in pregnancy may be prescribed by your Gynecologist please visit her.
For her even constipation is not good so take care of diet and intake of water.
She must continue to take Folic acid supplement
Please do not worry every thing will improve in few weeks time.
Have safe motherhood.