Jan,
In addition to seeing the gynecologist, I think your wife should see a hematologist. She should have iron studies blood testing done to see if her iron may be low. I think she should also discuss this pain with the hematologist. The location of the pain may give some indication as to its cause (possibly spleen or gallbladder related?). Thal minors typically drop to lower Hb levels during pregnancy than non carriers. Make sure your doctors are aware of this. Some minors do require a transfusion or two if their Hb falls below 8 during the pregnancy. Preparations for a blood transfusion during birth should also be made in case bleeding is heavy during the birth. This is simply a precaution that should be taken, but it is seldom necessary. Thal minors often have enlarged spleens that cannot be felt by a physical examination, but can be seen by ultrasound. If the spleen is suspected as a cause of the pain, an ultrasound can determine if the spleen is enlarged. Monitoring of bilirubin levels can also help tell if the gallbladder is involved. If the turnover of red blood cells during pregnancy increases over when she is not pregnant, its effects will be seen in the spleen and/or gallbladder.
I have mentioned the natural vitamin E and I hope she is taking it. I want to stress its importance to pregnant thal minors. I would also suggest looking for wheatgrass tablets or powder and having her take it through the pregnancy. It may help keep her Hb more stable.