Parity and breastfeeding (ref. parous who breastfed) parous without breastfeeding

Table 2. Regression coefficients between selected lifestyle, reproductive and other factors and log prolactin concentration among pre- and postmenopausal nurses and midwives. Results of multivariate analysis, mutually adjusted.

Factor Premenopausal women Postmenopausal women

β-coefficient SE P β-coefficient SE P

Parity and breastfeeding (ref. parous who breastfed) parous without breastfeeding

nulliparous

0.029 0.327

0.066 0.099

0.659 0.001

-0.080 -0.284

0.065 0.113

0.218 0.013

Age at menarche (years) 0.008 0.006 0.171 0.003 0.008 0.645

Age at menopause (years) 0.013 0.008 0.100

Current use of steroid medications or oral

contraceptives (Yes vs. No) -0.015 0.079 0.852 0.142 0.123 0.248

Menstrual cycle stage (follicular vs. other) -0.050 0.053 0.352

Family history of breast cancer (Yes vs. No) -0.064 0.102 0.531 0.001 0.093 0.989

BMI (kg/m

) 0.003 0.006 0.664 -0.007 0.006 0.239

Smoking during 24 h before blood sample

collection (Yes vs. No) -0.144 0.059 0.016 -0.209 0.063 0.001

Physical activity (MET) -0.010 0.032 0.742 0.012 0.034 0.715

Alcohol consumption 24 h before blood sample

collection (Yes vs. No) 0.068 0.084 0.419 -0.068 0.098 0.484

Coffee consumption (ref. <1 per week) 1-6 per week

daily

0.071 0.070

0.121 0.075

0.556 0.351

0.098 -0.002

0.127 0.076

0.438 0.977

Quality of sleep PSQI (score) -0.001 0.008 0.870 -0.008 0.009 0.339

Age (years) -0.002 0.007 0.732 -0.022 0.010 0.027

Season when blood sample was collected (July-Sep.

vs. Oct.-June) -0.159 0.085 0.063 -0.153 0.080 0.058

Time of blood sample collection (hours) -0.202 0.027 <0.001 -0.141 0.030 <0.001