Table 3

Adjusteda means of serum IGF-I, IGFBP-3, and molar ratio (IGF-I:IGFBP-3), by reproductive historyb and hormonal variables, Singapore Chinese Health Study

PredictorNumber of subjectsIGF-I (ng/ml)IGFBP-3 (ng/ml)Molar ratio (IGF-I:IGFBP-3)*1000
Age at menarche
 <17 years2741284233107
 ≥17 years521123956100
Age when periods became regular
 <17 years2561284254106
 ≥17 years601133912103
 Never became regular101163831102
P for <17 yrs vs. ≥17 yrs0.060.0030.47
Age at first birth
 ≤30 yrs2761244189104
 >30 yrs301384240116
P for (nullip. or ≤30 yrs vs. >30 yrs)0.260.850.13
Use of oral contraceptivesc
 Ex, >25 years at start641374236114
 Ex, ≤25 years at start20113410998
  • a Adjusted for age, BMI, and physical activity.

  • b Women who reportedly stopped bleeding, but had undergone a hysterectomy without double oophorectomy and an age at specimen collection <55 years were assigned an undetermined menopausal status.

  • c Only a single woman reported current use of oral contraceptives. She was excluded from the analysis.