Hi Kitkat,
Your child cannot be intermedia unless you are a beta thal zero, which is technically minor, but can manifest as intermedia. If you have two beta thal genes, you can only pass one onto your child, so at most, the child would be minor. Do you know if you have one or two beta thal genes?
There are quite a few thal majors in our group who have children, so hopefully you can get some feedback from personal experience of our members.
One possible complication that could occur is a drop in hemoglobin, so Hb level would need to be regularly checked. An important problem that should be watched for is the hypercoagulable state that sometimes occurs with pregnancies in thals, minor through major. This is a clotting disorder that is known to cause miscarriages in majors and intermedias and is suspected to be responsible for miscarriages in thal minor pregnancies, also. Aspirin and/or vitamin E daily, may be able to prevent this. Depending where you are located, you may be able to find a doctor with experience in thal pregnancies.
The drop in Hb that some thals experience during pregnancy is temporary. Getting a few transfusions won't make you transfusion dependent. Upping your folic acid dose and taking wheatgrass supplements may help to keep your Hb up.
Having children changes everyone's lives drastically, but I will leave it to the members with first hand experience to tell you what to expect in terms of thal.