Hi Rocker
Now that the meds and x-rays are out of the way, your wife would not be asked for further meds if she has a normal pregnancy.
It is an implied term of the visa process that you will notify DIAC of any material change in your circumstances prior to the point when you validate the visas. A visa does not "crystallise" until it is validated via making your Initial Entry to Oz using the new visa.
Whether or not a change is "material" is a matter of common-sense. If you become aware that your wife is pregnant before she validates her visa you should complete Form 1022 and send it in. Please see here:
http://www.immi.gov.au/allforms/pdf/1022.pdf
It would be prudent to disclose the pregnancy because you could get a situation where your visa is granted, you plan that Baby will be born in Australia but then Mum develops high blood pressure and the doctors ground her until after Baby is born. In those circumstances you would need a Child Visa for Baby and there would be questions about why the pregnancy was not disclosed.
However if it is normal, healthy pregnancy the Medical Officer of the Commonwealth would be unlikely to want any further medical examinations etc. I would simply get a letter from the doctor managing your wife's pregancy confirming that all is well and I would expect to hear no more about it. They might be interested if she turns out to be carrying twins and probably would be interested if it is triplets, but only in as much as doctors worry more if there is more than one baby invlved.
It is equally possible though that your wife might be so newly pregnant by the time she travels to Oz that she would not be aware that she is pregnant till after she arrives in Oz. The run-up to the Big Move is alsways so hectic that early hints of pregnancy could easily be mistaken for being the symptoms of stress. I'm sure that happens frequently.
This is one of the situations which it is best not to try to lprepare for and just deal with it if and when it happens because it is impossible to predict exactly when your wife might become pregnant and therefore it is impossible to make viable plans about in in advance.
Unless......!!!
Do you have reason to suspect that your wife is pregnant?
Best wishes
Gill