Fig 1.
Relationships between gestational diabetes (GDM) and age (Fig 1A), weight (Fig 1B), free thyroxine (fT4) (Fig 1C), and thyrotropin (TSH) (Fig 1D).
Open circles represent percents of GDM cases at each decile of the variable shown on the X-axis. Solid lines indicate unadjusted slopes of the respective relationships; p-values indicate slope significance. The dotted line in Fig 1C shows the slope of the fT4/GDM relationship, after adjustment for age, weight, and TSH.
Table 1.
Characteristics of women with and without gestational diabetes.
Table 2.
Thyrotropin (TSH), free thyroxine (fT4) and thyroperoxidase (TPO) antibodies among women with and without gestational diabetes (GDM).
Table 3.
Extent to which variables that differ significantly between women with and without gestational diabetes might influence fT4 concentration (9,079 women without gestational diabetes).
Fig 2.
Second trimester relationships between free thyroxine (fT4), maternal weight, and gestational diabetes in the FaSTER trial.
A to E Indicates that there is an inverse relationship between maternal weight and fT4 [13, 14, 21]; E to B Indicates that lower fT4 is associated with a higher GDM rate [7]; A to B Indicates that higher weight is associated with higher GDM rate.
Fig 3.
Schematic diagram depicting how caloric intake and deiodinase activity fit into relationships shown in Fig 2.
Higher caloric intake (C) reflects higher weight (A) and induces higher deiodinase activity (D) [32, 34]. Lower fT4 (E) and higher T3/T4 ratios (F) occur as a consequence of higher deiodinase activity and are associated with both insulin resistance (G) [24, 25] and gestational diabetes (B).