Clinical TSH Guidelines

The study's identified safe TSH range (1.32–2.12 mIU/L) is narrower than the ATA threshold, meaning TSH values within the conventionally normal range can still carry increased LGA risk in young women. The American Thyroid Association guidelines set the upper TSH limit at 4.0 mIU/L for TPO Ab-negative pregnant women and 2.5 mIU/L for TPO Ab-positive women. The findings are exploratory and do not justify pharmacological intervention, but should prompt individualised pregnancy monitoring and heightened clinical vigilance for young preconception women with TSH outside the safe range. Prior work by the same research group found that TSH above 2.5 mIU/L before pregnancy was associated with increased risk of both LGA and SGA.