Table 4.
Clinical characteristics of participants with normal thyroid function and SCH/OH.
| Variables | TSH<2.5µIU/mL | 2.5µIU/mL≤TSH≤4.2µIU/mL | SCH/OH | P |
| N | 1771 | 769 | 290 | |
| Age (years) | 32.00 [29.00, 35.00] | 32.00 [29.00, 35.00] | 32.00 [29.00, 35.00] | 0.284 |
| BMI (kg/m2) | 20.76 [19.23, 22.58] | 20.96 [19.47, 22.86] | 21.36 [20.03, 24.03] | <0.001b,c |
| Duration of infertility (years) | 3.00 [2.00, 5.00] | 3.00 [2.00, 5.00] | 3.00 [2.00, 5.00] | 0.388 |
| Infertility type, n (%) | ||||
|---|---|---|---|---|
| Primary infertility | 815 (46.0) | 363 (47.2) | 156 (53.8) | 0.049c |
| Secondary infertility | 956 (54.0) | 406 (52.8) | 134 (46.2) | |
| TSH (µIU/mL) | 1.62 [1.23, 2.02] | 3.07 [2.76, 3.51] | 5.08 [4.54, 6.34] | <0.001a,b,c |
| FT4 (ng/dL) | 1.25 [1.15, 1.36] | 1.24 [1.13, 1.34] | 1.20 [1.10, 1.30] | <0.001b,c |
| FT3 (pg/mL) | 2.93 [2.71, 3.14] | 2.98 [2.76, 3.23] | 2.99 [2.75, 3.20] | <0.001a |
| TPOAb (IU/mL) | 5.95 [1.51, 11.72] | 7.31 [2.41, 13.89] | 9.33 [3.42, 42.90] | <0.001a,b,c |
| TgAb (IU/mL) | 12.16 [4.50, 22.18] | 13.41 [6.80, 34.15] | 14.69 [7.93, 187.00] | <0.001c |
| Positive TPOAb, n(%) | 164 (9.3) | 97 (12.6) | 79 (27.2) | <0.001a,b,c |
| Positive TgAb, n(%) | 196 (11.1) | 131 (17.0) | 82 (28.3) | <0.001a,b,c |
| Positive TAI, n(%) | 246 (13.9) | 150 (19.5) | 95 (32.8) | <0.001a,b,c |
| LH (IU/L) | 4.85 [3.69, 6.34] | 5.02 [3.90, 6.57] | 4.80 [3.59, 6.45] | 0.069 |
| E2 (pg/mL) | 35.00 [26.00, 47.30] | 34.00 [26.20, 48.00] | 32.60 [24.15, 45.65] | 0.087 |
| AMH (ng/mL) | 3.44 [1.96, 5.58] | 3.33 [1.91, 5.23] | 2.79 [1.46, 4.82] | <0.001c |
| AFC (n) | 10.00 [6.00, 14.00] | 10.00 [6.00, 14.00] | 9.00 [6.25, 14.00] | 0.852 |
| FSH (mIU/mL) | 6.72 [5.82, 7.98] | 6.93 [5.90, 8.14] | 7.03 [6.06, 8.09] | 0.062 |
| Prevalence of AMH< 1.2 ng/mL, n(%) | 204 (11.5) | 104 (13.5) | 50 (17.2) | 0.017c |
| Prevalence of AFC<5, n(%) | 214 (12.1) | 115 (15.0) | 43 (14.8) | 0.097 |
| Prevalence of DOR, n(%) | 106 (6.0) | 60 (7.8) | 29 (10.0) | 0.022c |
All data is presented as median [25th percentile, 75th percentile] or n (%).
Superscripts indicate significant differences between aTSH<2.5µIU/mL and 2.5µIU/mL≤TSH≤4.2µIU/mL, b2.5µIU/mL≤TSH≤4.2µIU/mL and SCH/OH, and cTSH<2.5µIU/mL and SCH/OH.
Kruskal-Wallis rank-sum test is applied for comparisons among three groups of continuous variables, with pairwise comparisons via Dunn’s with Bonferroni correction. Categorical variables are compared using chi-squared test, with pairwise comparisons among multiple groups are conducted using the chi-square partitioning method.
SCH/OH, Subclinical/overt hypothyroidism; BMI, body–mass index; TSH, thyroid stimulating hormone; FT4, free thyroxine; FT3, free triiodothyronine; TPOAb, thyroid peroxidase antibody; TgAb, thyroglobulin antibody; TAI, thyroid autoimmunity; LH, luteinizing hormone; E2, estradiol; AMH, anti-müllerian hormone; AFC, antral follicle count; FSH, follicle stimulating hormone; DOR, diminished ovarian reserve.