Table 4: Associations between maternal thyroid hormone levels during pregnancy (27 weeks’ gestation) and child neurodevelopment at 6, 12 and 24 months of age.

Bayley scalesPreschool language scale
Mental development indexPsychomotor development indexAuditory comprehensionExpressive comprehensionTotal score

6 Months1Free T4β−3.14−3.27−2.031.65−0.10
(95% CI)(−7.65, 1.36)(−9.36, 2.82)(−9.80, 5.75)(−5.48, 8.79)(−6.45, 6.25)
Total T4β0.03−0.06−0.240.580.19
(95% CI)(−0.57, 0.62)(−0.86, 0.74)(−1.28, 0.80)(−0.37, 1.53)(−0.66, 1.05)
TSHβ0.851.461.510.241.06
(95% CI)(−0.49, 2.18)(−0.33, 3.26)(−0.81, 3.84)(−1.91, 2.38)(−0.87, 2.98)

12 Months2Free T4β−0.48−6.404.391.263.45
(95% CI)(−6.22, 5.26)(−13.89, 1.08)(−3.56, 12.34)(−7.20, 9.72)(−4.76, 11.67)
Total T4β−0.12−0.450.33−0.150.12
(95% CI)(−0.92, 0.68)(−1.53, 0.63)(−0.79, 1.46)(−1.34, 1.04)(−1.05, 1.28)
TSHβ1.710.102.920.461.91
(95% CI)(0.05, 3.37)*(−2.16, 2.35)(0.59, 5.25)*(−2.04, 2.95)(−0.51, 4.33)

24 Months3Free T4β−4.29−2.67
(95% CI)(−11.60, 3.02)(−8.95, 3.62)
Total T4β−0.170.43
(95% CI)(−1.20, 0.85)(−0.43, 1.30)
TSHβ0.33−1.31
(95% CI)(−1.97, 2.63)(−3.25, 0.63)

.
1Models adjusted for maternal age, employment status at enrollment and at the 6-months visit, country of birth, time lived in the US, Diet Quality Index, blood lead levels and delivery complications; child hospitalization before 6 months, season of assessment and psychometrician.
2Models adjusted for maternal age, employment status at enrollment and at the 6 months visit, country of birth, time lived in the US, Diet Quality Index, Kotelchuck Adequacy of Prenatal Care Utilization Index, blood lead levels, delivery complications and PPVT score; child age, preterm birth, hospitalization at 6 months and 1 year, family structure at 1 year; season, and language spoken at the time of assessment.
3Models adjusted for maternal age, income, employment status at enrollment, 6 months and 1 year, country of birth, Diet Quality Index, Kotelchuck Adequacy of Prenatal Care Utilization Index, blood lead levels, delivery complications, PPVT score; child hospitalization at 1 year; number of children in the home at 6 months, home density at 2 years, family structure at 1 year; season, psychometrician and language of assessment.
4Since TSH was expressed on a log2 basis, β are equal to the change in neurodevelopmental outcomes for a doubling in TSH levels.