Insulin-like growth factor-1, growth hormone, and daily cycling estrogen are associated with mammographic density in premenopausal women

Background: Mammographic density represents epithelial and stromal proliferation, while Insulin-like growth factor (IGF)-1, IGF-binding protein (IGFBP)-3, growth hormone (GH) and estrogen, may influence cellular proliferation. However, whether these growth factors independently, or in combination with estrogen, influence mammographic density in premenopausal women remains unclear. Material and methods: Growth factors were assessed in 202 ovulating premenopausal women participating in the Energy Balance and Breast cancer Aspects (EBBA)-I study. Estrogen was assessed in serum, and daily in saliva, throughout a menstrual cycle. Computer-assisted mammographic density (Madena) was obtained from digitized mammograms (days 7-12 of the menstrual cycle). Associations between growth factors, estrogen and percent mammographic density, were studied in regression models. Results: Women with a mean age of 30.7 years had a mean percent mammographic density of 29.8%. Among women in the strata (above median split) of IGF-1 (>25 nmol/l) or GH (>0.80 mlU/l), we observed that an increase in salivary 17β–estradiol, was associated with a higher odds for having higher percent mammographic density (>28.5 %). The odds ratios (ORs) per standard deviation increase of 17β-estradiol, were 1.81 (95% confidence interval [CI] 1.08-3.03) in the high IGF-1 stratum, and 2.08 (95% CI 1.10-3.94) in the high GH stratum. Furthermore, women in this strata of growth factors (above median) who had an overall average 17β–estradiol above median (>16.8 pmol/l), had higher ORs for having higher percent mammographic density (>28.5%): IGF-1 4.13 (95% CI 1.33-12.83), and GH 4.17 (95% CI 1.41-12.28). Conclusion: Growth factors, in combination with cycling estrogen, were associated with percent mammographic density, of potential clinical relevance.Anthropolog

Duration of Lactation, Maternal Metabolic Profile, and Body Composition in the Norwegian EBBA I-Study

Objective There is conflicting evidence as to whether duration of lactation may decrease the risk of subsequent development of an unfavorable maternal metabolic profile including overweight and obesity. We hypothesized that duration of lactation is associated with a more favorable metabolic profile and healthier anthropometrical measurements. Methods 98 parous women from the Norwegian EBBA I-study (Energy Balance and Breast cancer Aspects-study), a cross-sectional study of healthy premenopausal women aged 25–35 years, historical lactation data were collected, anthropometrical measurements were taken, fasting blood samples (serum glucose, triglycerides, total cholesterol and HDL-cholesterol) were drawn and women were asked to fill in a pre-coded food diary. Results Mean time since last birth was 4.7 years, mean number of children was 1.9, mean total duration of lactation was 19 months and average length of lactation per child was 10.3 months. Women who on average lactated for less than 10 months per child had higher mean levels of fasting serum glucose (5.2 mmol/L vs. 5.0 mmol/L, p = 0.04), serum triglyceride (0.91 mmol/L vs. 0.66 mmol/L, p = 0.001) and serum cholesterol (4.78 mmol/L vs. 4.32 mmol/L, p = 0.004), and a higher waist-to-hip ratio (0.81 vs. 0.77, p = 0.001) than women who lactated for 10 months or more per child. The inverse association between average length of lactation per child and waist-to-hip ratio persisted after adjustment for potential confounders. Conclusions These results support the hypothesis that duration of lactation may be associated with a healthier metabolic profile and healthier anthropometrical measurements, especially lipid levels and waist-to-hip ratio even years after weanin

Duration of Lactation, Maternal Metabolic Profile, and Body Composition in the Norwegian EBBA I-Study

Objective There is conflicting evidence as to whether duration of lactation may decrease the risk of subsequent development of an unfavorable maternal metabolic profile including overweight and obesity. We hypothesized that duration of lactation is associated with a more favorable metabolic profile and healthier anthropometrical measurements. Methods 98 parous women from the Norwegian EBBA I-study (Energy Balance and Breast cancer Aspects-study), a cross-sectional study of healthy premenopausal women aged 25–35 years, historical lactation data were collected, anthropometrical measurements were taken, fasting blood samples (serum glucose, triglycerides, total cholesterol and HDL-cholesterol) were drawn and women were asked to fill in a pre-coded food diary. Results Mean time since last birth was 4.7 years, mean number of children was 1.9, mean total duration of lactation was 19 months and average length of lactation per child was 10.3 months. Women who on average lactated for less than 10 months per child had higher mean levels of fasting serum glucose (5.2 mmol/L vs. 5.0 mmol/L, p = 0.04), serum triglyceride (0.91 mmol/L vs. 0.66 mmol/L, p = 0.001) and serum cholesterol (4.78 mmol/L vs. 4.32 mmol/L, p = 0.004), and a higher waist-to-hip ratio (0.81 vs. 0.77, p = 0.001) than women who lactated for 10 months or more per child. The inverse association between average length of lactation per child and waist-to-hip ratio persisted after adjustment for potential confounders. Conclusions These results support the hypothesis that duration of lactation may be associated with a healthier metabolic profile and healthier anthropometrical measurements, especially lipid levels and waist-to-hip ratio even years after weanin