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Table 1 Demographic and clinical characteristics and anti-Müllerian hormone (AMH) of the study population, total population (n=2,276), Seoul (n=1,122), and non-Seoul (n=1,154) residents

From: Outdoor air pollution and diminished ovarian reserve among infertile Korean women

  Total population (n=2276) Seoul residents (n=1122) Non-Seoul residents (n=1154) P for differenceb
Age (year) 36.6 ± 4.2 36.2 ± 4.1 37.0 ± 4.3 < 0.001
BMI (kg/m2) 21.7 ± 3.1 21.4 ± 3.0 22.1 ± 3.3 0.826
 < 18.5 243 (10.7%) 129 (11.5%) 114 (9.9%) < 0.001
 18.5–23 1431 (62.8%) 746 (66.5%) 685 (59.4%)
 23–25 300 (13.2%) 128 (11.4%) 172 (14.9%)
 ≥ 25 302 (13.3%) 119 (10.6%) 183 (15.8%)
Timing of blood test
 Mar–May 750 (33.0%) 358 (31.9%) 392 (34.0%) 0.622
 June–Aug 489 (21.5%) 252 (22.5%) 237 (20.5%)
 Sept–Nov 337 (14.8%) 171 (15.2%) 166 (14.4%)
 Dec–Feb 700 (30.8%) 341 (30.4%) 359 (31.1%)
Smoking history 51 (2.2%) 28 (2.5%) 23 (2.0%) 0.584
Currently working 1431 (62.9%) 783 (69.8%) 648 (56.2%) < 0.001
AMH (ng/mL) 3.3 ± 3.1 3.5 ± 3.2 3.1 ± 3.0 0.001
AMH ratioa 0.8 ± 0.7 0.8 ± 0.7 0.8 ± 0.7 0.055
Low AMH (< 0.5 ng/mL) 235 (10.3%) 81 (8.6%) 154 (13.3%) 0.025
  1. BMI body mass index, AMH anti-Müllerian hormone
  2. aRatio of observed AMH to age-specific AMH. Age-specific AMH was calculated from a quadratic model (logAMH = −1.442 + 0.225 × age − 0.004 × age2) [30]
  3. bP values for difference between Seoul residents and non-Seoul residents. Wilcoxon rank sum test and chi-square test were used for comparison
  4. Due to missing information, sum of columns may not equal to the number of total population