Good question! That could have saved me and my premature baby a lot of agony. My endo did say that within the past five years, they are getting better at checking. I suppose it depends on the doctor. Many doctors, even endos, still do not know enough about diagnosing and treating thyroid disease.
I agree, it should be a standard test. I have had thyroid problems that went undiagnosed through my current pregnancy. The tests were only done at my request and then the doctors didn't want to treat my hypo condition which is crucial during pregnancy. It's very frustrating.
I am finally on meds, thanks to my general doc. But the ob's & the endo were absolutely NO help.