Yes—pregnancy-specific ranges may overcount mild underactive thyroid cases, flagging 3.6% versus 1.5% with standard ranges. The study used data from Generation R Next in Rotterdam. It included 1,058 women before pregnancy and 2,084 during pregnancy. Researchers compared pregnancy-specific lab ranges with ranges used outside pregnancy. They also tested whether Free T3 (Triiodothyronine), a thyroid hormone, helped identify thyroid disease. Before pregnancy, 2.2% of women had blood tests suggesting a mildly underactive thyroid. During pregnancy, that figure was 3.6% using pregnancy-specific ranges and 1.5% using standard ranges. The authors concluded that pregnancy-specific ranges likely label too many mild cases. These results concern how tests are labeled, not proof of harm. The pattern differed for tests suggesting a mildly overactive thyroid. Standard ranges flagged 11.1% of women during pregnancy. Pregnancy-specific ranges flagged 1.5%, compared with 2.0% before pregnancy. So changing the range did not move every thyroid label the same way. The extra thyroid hormone test changed some labels, but its overall added value was limited. Among pregnancy cases initially labeled mildly overactive, 14.3% were reclassified as overactive. Before pregnancy, the figure was 5.6%. Those percentages describe that smaller group—not all women in the study. For members tracking thyroid numbers, the range matters alongside the result. Saving the lab’s range and whether testing happened before or during pregnancy adds useful context. When comparing notes here, those details can help explain different flags on similar results. This study does not show that an extra test improves health outcomes. What changes have you noticed in your thyroid numbers or lab flags before or during pregnancy?