Table 1.
Patient characteristics and hypothyroidism treatment—overall and by treatment status
| Variable | All pregnant women (N = 3448) | Treated with levothyroxine (N = 2340) | Untreated (N = 1108) | P value |
|---|---|---|---|---|
| N (%), mean ± SD or median [IQ range] | N (%), mean ± SD or median [IQ range] | N (%), mean ± SD or median [IQ range] | ||
| Patient characteristics | ||||
| Age (mean ± SD) | 32.76 ± 4.80 | 32.57 ± 4.76 | 33.14 ± 4.87 | 0.0018 |
| Region [n (%)] | < 0.0001 | |||
| Northeast | 542 (15.72) | 371 (15.85) | 171 (15.43) | |
| Midwest | 581 (16.85) | 421 (17.99) | 160 (14.44) | |
| South | 1541 (44.69) | 976 (41.71) | 565 (50.99) | |
| West | 781 (22.65) | 570 (24.36) | 211 (19.04) | |
| Other | 3 (0.09) | 2 (0.09) | 1 (0.09) | |
| Insurance plan type [n (%)] | 0.9254 | |||
| Exclusive provider organization | 438 (12.70) | 297 (12.69) | 141 (12.73) | |
| Health maintenance organization | 117 (3.39) | 77 (3.29) | 40 (3.61) | |
| Indemnity | 1 (0.03) | 1 (0.04) | 0 (0.00) | |
| Point of service | 2831 (82.11) | 1922 (82.14) | 909 (82.04) | |
| Preferred provider organization | 61 (1.77) | 43 (1.84) | 18 (1.62) | |
| Diagnosing physician [n (%)]a | < 0.0001 | |||
| Endocrinologist | 394 (11.43) | 208 (8.89) | 186 (16.79) | |
| Family medicine | 333 (9.66) | 246 (10.51) | 87 (7.85) | |
| Internal medicine | 239 (6.93) | 159 (6.79) | 80 (7.22) | |
| Obstetrics and gynecology | 483 (14.01) | 355 (15.17) | 128 (11.55) | |
| General acute care hospital | 575 (16.68) | 417 (17.82) | 158 (14.26) | |
| Other | 1424 (41.30) | 955 (40.81) | 469 (42.33) | |
| Charlson comorbidity Index (mean ± SD) | 0.18 ± 0.53 | 0.16 ± 0.50 | 0.21 ± 0.60 | 0.0086 |
| Visit endocrinologist [n (%)] | 424 (12.30) | 227 (9.70) | 197 (17.78) | < 0.0001 |
| TSH (median [IQ range]) | 1.97 [1.27–3.53] | 1.98 [1.30–3.48] | 1.93 [1.22–3.86] | 0.5044 |
| No. of TSH laboratory results [n (%)] | 0.1433 | |||
| Zero | 806 (23.38) | 527 (22.52) | 279 (25.18) | |
| One | 375 (10.88) | 256 (10.94) | 119 (10.74) | |
| Two–four | 1061 (30.77) | 746 (31.88) | 315 (28.43) | |
| Five or more | 1206 (34.98) | 811 (34.66) | 395 (35.65) | |
SD standard deviation, IQ interquartile, TSH thyroid-stimulating hormone
T tests, Wilcoxon rank-sum tests and chi-square tests were used to examine differences in means, medians and proportions, respectively