Table 1

General characteristics of the study population

First stageSecond stage
N19991496
Age (years)37.5±11.137.3±10.8
Body mass index (kg/m2)23.3±3.423.4±3.3
Smoking status (%)
 Non-smoker (%)984 (49.2)725 (48.5)
 Smoker (%)1015 (50.8)771 (51.5)
Testosterone (ng/mL)6.3±1.96.3±2.4
Oestradiol (pg/mL)*3.5±0.32.7±0.1
FSH (mIU/mL)*1.7±0.61.7±0.6
LH (mIU/mL)5.6±2.75.6±3.0
SHBG (nmol/L)*3.6±0.53.8±0.5
  • Data shown with±are given as mean±SD unless indicate otherwise.

  • *Variables were log-transformed.

  • FSH, follicle-stimulating hormone; LH, luteinising hormone; SHBG, sex hormone binding globulin.