Maternal thyroid hormones predict birth weight

  • Zhang C & al.
  • J Clin Endocrinol Metab
  • 19 Jun 2019

  • International Clinical Digest
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Takeaway

  • Levels of thyroid-stimulating hormone (TSH), triiodothyronine (T3), and free thyroxine (FT4) during pregnancy are associated with birth weight.

Why this matters

  • Birth weight has been linked to risk for obesity and diabetes, and the role of maternal thyroid function in birth weight needed further clarification.

Key results

  • High TSH levels during the first or third trimester were associated with reduced birth weight (P=.0083 and P<.0001 respectively high levels during the third trimester were associated with increased risk for small gestational age p=".0031).</li">
  • High FT4 levels during the first or third trimester were associated with reduced birth weight, increased risk for SGA, and reduced risk for large for gestational age (LGA; P<.0001 for all>
  • High T3 levels during the first or third trimester were associated with greater birth weight and increased risk for LGA (P<.0001 for all>

Study design

  • 46,186 pregnant people were analyzed for thyroid hormone levels and associations with birth weight.
  • Funding: National Natural Science Foundation of China; Shanghai Municipal Commissions of Health and Family Planning Program.

Limitations

  • No analysis of maternal iodine or iron.
  • No measurement of FT3, TT4, or TgAb concentrations.