title: Breast Feeding Is Associated with Postmenopausal Bone Loss: Findings from the Korea National Health and Nutrition Examination Survey.
abstract: BACKGROUND
  Postmenopausal osteoporosis is a common disease which can cause various morbidity and economic burden. Lactation is known to cause a decline in bone mineral density (BMD), but there are controversies on whether decreased BMD is fully recovered after lactation and whether lactation duration has an influence on postmenopausal BMD. This study was conducted to see whether breastfeeding is associated with postmenopausal bone loss using a highly representative sample of Korean population.
  
  
  METHODS
  Retrospective cross sectional study was done using data collected from Korea National Health and Nutrition Examination Survey V. The study outcome was BMD measured with dual-energy X-ray absorptiometry and divided into 2 groups: normal or low BMD (T score<-1), and breastfeeding duration was categorized into 4 groups (never, 1st, 2nd, and 3rd tertile). Logistic regression analysis was done to examine the association between lactation duration and BMD.
  
  
  RESULTS
  Among 1,694 postmenopausal women (mean age, 63.5±9.1), 85.71% were in low BMD group. Compared to never breastfeeding group, postmenopausal women with longer than 79 months of breastfeeding duration are more likely to have low BMD (adjusted risk ratio [ARR]=1.24; 95% confidence interval, 1.17 to 1.32). As the duration of breastfeeding increases, ARR and risk difference for low BMD also increases (P for trend=0.008).
  
  
  CONCLUSIONS
  The study results showed that total breastfeeding duration was associated with postmenopausal low BMD. All women planning on breastfeeding should be aware of its risks and should take adequate dietary calcium and vitamin D before, during, and after breastfeeding.
authors.affiliation: Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Hyun Joo
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Family Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea.
authors.forename: Hyuktae
authors.initials: H
authors.lastname: Kwon
authors.affiliation: Department of Family Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea.
authors.forename: Seung-Won
authors.initials: SW
authors.lastname: Oh
authors.affiliation: Department of Family Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea.
authors.forename: Cheol Min
authors.initials: CM
authors.lastname: Lee
authors.affiliation: Health Service Center, Seoul National University, Seoul, Korea.
authors.forename: Hee-Kyung
authors.initials: HK
authors.lastname: Joh
authors.affiliation: Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Youngju
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Yoo-Jin
authors.initials: YJ
authors.lastname: Um
authors.affiliation: Department of Family Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Sang Hyun
authors.initials: SH
authors.lastname: Ahn
keywords: Bone Density; Breast Feeding; Lactation; Postmenopausal