 There is general agreement that thyroid gland function should be assessed in pregnant women. When the gland produces too little thyroid hormone hypothyroidism, all of the womans bodily functions slow down, and there are problems with her babys development. Until now, physicians have identified this problem on an individual basis case-finding, but this approach misses many of the cases. Our trial aims to replace case-finding with a routine blood test that is highly effective at detecting hypothyroidism, thereby allowing treatment to correct the deficiency. This approach can eventually be implemented throughout the United States. 