Table 3.
Pregnancy and Delivery Characteristics of 920 Euthyroid Women With SGA Babies, Stratified by FT4 Concentration at 15.0–18.9 Weeks' Gestation, After Accounting for Maternal Weight and Other Relevant Variables
| Characteristic | All | FT4 Quintilea |
P Valueb | ||||
|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | |||
| n | 920 | 170 | 200 | 166 | 169 | 215 | |
| FT4, pmol/L | 13.03 (1.92)c | 10.58 (0.92) | 12.13 (0.33) | 13.03 (0.27) | 13.93 (0.28) | 15.35 (1.02) | |
| TSH, mIU/L | 1.22 (0.26) | 1.24 (0.29) | 1.26 (0.26) | 1.25 (0.26) | 1.23 (0.26) | 1.16 (0.25) | .13 |
| Antibody positive, % | 11.5 | 16.5 | 11.0 | 11.4 | 9.5 | 9.8 | .36 |
| Age, y | 29 (5.7) | 32 (5.3) | 30 (5.6) | 28 (5.7) | 28 (6.0) | 27 (5.4) | <.001 |
| Maternal weight, kg | 65.9 (16.4) | 70.5 (17.0) | 66.8 (17.2) | 65.9 (17.9) | 63.6 (16.0) | 62.3 (12.2) | <.001 |
| BMI, kg/m2 | 24.1 (5.9) | 26.0 (6.6) | 24.4 (6.0) | 24.2 (6.1) | 23.7 (5.6) | 22.8 (4.4) | <.001 |
| Gestational diabetes, % | 3.4 | 6.5 | 2.5 | 3.6 | 4.7 | 0.5 | .007 |
| Gestational age, wk | 37.4 (2.3) | 37.0 (2.5) | 37.6 (2.4) | 37.3 (2.0) | 37.7 (2.2) | 37.4 (2.4) | .72 |
| GA < 37 wk, % | 40.7 | 48.2 | 41.5 | 43.4 | 31.4 | 39.1 | .59 |
| Birth weight, g | 2608 (394) | 2621 (421) | 2580 (392) | 2637 (348) | 2608 (372) | 2580 (420) | .03 |
| Preeclampsia, % | 3.6 | 4.1 | 5.5 | 4.2 | 1.2 | 2.8 | .47 |
| Preterm-PROM, % | 8.6 | 12.4 | 9.5 | 6.6 | 7.1 | 7.4 | .49 |
| Premature labor, % | 21.5 | 23.5 | 23.5 | 19.9 | 19.5 | 20.9 | .81 |
| Placental abruption, % | 3.9 | 4.7 | 4.5 | 4.2 | 4.7 | 1.9 | .08 |
| Placenta previa, % | 1.7 | 0.6 | 1.5 | 2.4 | 1.2 | 2.8 | .18 |
| Intrauterine fetal death, % | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | .99 |
Abbreviations: GA, gestational age; PROM, premature rupture of membranes; Adjustments use the MoM methodology described in Materials and Methods: predicted birth weight = 1495.17 + 981.71 (log weight) + 47.93 (race) − 182.77 (smoking) + 40.23 (parity) + 70.92 (college). SGA is defined as below the 10th centile for a given gestational age and maternal weight.
Cutoffs for FT4 quintiles are 11.481, less than 12.642, less than 13.545, and less than 14.577 pmol/L.
Student's t test is for quintile 5 vs quintiles 1–4; χ2 test for categorical dependent variables.
Results are reported as median (SD); for TSH, results are expressed as median (log SD).