BACKGROUND: Maternal clinical thyroid disorders can cause reproductive complications. However, the effects of mild thyroid dysfunctions are not yet well established. The aim was to evaluate the association of maternal thyroid function during the first half of pregnancy with birthweight and preterm delivery. METHODS: We analysed data on 2170 pregnant women and their children from a prospective population-based cohort study in four Spanish areas. Mid-gestation maternal serum and urine samples were gathered to determine thyroid-stimulating hormone (TSH), free thyroxine (fT4 ), and urinary iodine concentration (UIC). Thyroid status was defined according to percentile distribution as: euthyroid (TSH and fT4 >5th and <95th percentiles); hypothyroxinaemia (fT4 < 5 th percentile and TSH normal), hypothyroidism (TSH > 95th percentile and fT4 normal or <5th percentile), hyperthyroxinaemia (fT4 > 95 th percentile and TSH normal), and hyperthyroidism (TSH < 5 th percentile and fT4 normal or >95th percentile). Response variables were birthweight, small and large for gestational age (SGA/LGA), and preterm delivery. RESULTS: An inverse association of fT4 and TSH with birthweight was found, the former remaining when restricted to euthyroid women. High fT4 levels were also associated with an increased risk of SGA [odds ratio, 95% confidence interval (CI) 1.28 (95% CI 1.08, 1.51)]. Mean birthweight was higher in the hypothyroxinaemic group (β = 109, P < 0.01). Iodine intake and UIC were not associated with birth outcomes. CONCLUSIONS: High maternal fT4 levels during the first half of pregnancy were related to lower birthweight and increased risk of SGA newborns, suggesting that maternal thyroid function may affect fetal growth, even within the normal range.
BACKGROUND: Maternal clinical thyroid disorders can cause reproductive complications. However, the effects of mild thyroid dysfunctions are not yet well established. The aim was to evaluate the association of maternal thyroid function during the first half of pregnancy with birthweight and preterm delivery. METHODS: We analysed data on 2170 pregnant women and their children from a prospective population-based cohort study in four Spanish areas. Mid-gestation maternal serum and urine samples were gathered to determine thyroid-stimulating hormone (TSH), free thyroxine (fT4 ), and urinary iodine concentration (UIC). Thyroid status was defined according to percentile distribution as: euthyroid (TSH and fT4 >5th and <95th percentiles); hypothyroxinaemia (fT4 < 5 th percentile and TSH normal), hypothyroidism (TSH > 95th percentile and fT4 normal or <5th percentile), hyperthyroxinaemia (fT4 > 95 th percentile and TSH normal), and hyperthyroidism (TSH < 5 th percentile and fT4 normal or >95th percentile). Response variables were birthweight, small and large for gestational age (SGA/LGA), and preterm delivery. RESULTS: An inverse association of fT4 and TSH with birthweight was found, the former remaining when restricted to euthyroid women. High fT4 levels were also associated with an increased risk of SGA [odds ratio, 95% confidence interval (CI) 1.28 (95% CI 1.08, 1.51)]. Mean birthweight was higher in the hypothyroxinaemic group (β = 109, P < 0.01). Iodine intake and UIC were not associated with birth outcomes. CONCLUSIONS: High maternal fT4 levels during the first half of pregnancy were related to lower birthweight and increased risk of SGA newborns, suggesting that maternal thyroid function may affect fetal growth, even within the normal range.
Authors: Lauren E Johns; Kelly K Ferguson; David E Cantonwine; Bhramar Mukherjee; John D Meeker; Thomas F McElrath Journal: J Clin Endocrinol Metab Date: 2018-04-01 Impact factor: 5.958
Authors: Jessica Farebrother; Kathryn V Dalrymple; Sara L White; Carolyn Gill; Anna Brockbank; John H Lazarus; Keith M Godfrey; Lucilla Poston; Angela C Flynn Journal: Eur J Clin Nutr Date: 2020-11-12 Impact factor: 4.016
Authors: Arash Derakhshan; Robin P Peeters; Peter N Taylor; Sofie Bliddal; David M Carty; Margreet Meems; Bijay Vaidya; Liangmiao Chen; Bridget A Knight; Farkhanda Ghafoor; Polina V Popova; Lorena Mosso; Emily Oken; Eila Suvanto; Aya Hisada; Jun Yoshinaga; Suzanne J Brown; Judit Bassols; Juha Auvinen; Wichor M Bramer; Abel López-Bermejo; Colin M Dayan; Robert French; Laura Boucai; Marina Vafeiadi; Elena N Grineva; Victor J M Pop; Tanja G Vrijkotte; Leda Chatzi; Jordi Sunyer; Ana Jiménez-Zabala; Isolina Riaño; Marisa Rebagliato; Xuemian Lu; Amna Pirzada; Tuija Männistö; Christian Delles; Ulla Feldt-Rasmussen; Erik K Alexander; Scott M Nelson; Layal Chaker; Elizabeth N Pearce; Mònica Guxens; Eric A P Steegers; John P Walsh; Tim I M Korevaar Journal: Lancet Diabetes Endocrinol Date: 2020-06 Impact factor: 44.867