Try our beta test site
IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more...

Longitudinal Lactation Bone Density Study

This study has been completed.
Information provided by (Responsible Party):
Mara Horwitz, University of Pittsburgh Identifier:
First received: June 20, 2012
Last updated: June 15, 2016
Last verified: June 2016

Changes in maternal calcium metabolism are necessary during lactation to provide adequate calcium in breast milk for development of the newborn skeleton. The calcium in milk is derived from the maternal skeleton, resulting in significant bone loss, a process thought to be mediated by the actions of parathyroid hormone-related protein (PTHrP) in combination with a decreased estrogen levels. After weaning, bone lost during lactation is rapidly regained.

Differences between African-American and Caucasian bone metabolism are well documented and include higher bone mineral density (BMD), lower risk of fragility fracture, lower 25-hydroxyvitamin D (25(OH) D), and higher PTH in African-Americans compared to Caucasians. Most studies of bone metabolism in lactating women have been done in Caucasians. Because of differences in bone metabolism between African-Americans and Caucasians, we do not know whether African-Americans will have similar findings.

The primary aim of this study is to compare the changes in bone mineral density (BMD) during lactation in African-Americans with those in Caucasians. It is not known whether the loss in BMD during lactation will be the same for both races. African-Americans display skeletal resistance to PTH with short-term infusions and have lower bone resorption, higher BMD and lower fracture risk than Caucasians. A recent study by our group indicated that lactating African-American mothers had slightly lower bone resorption but quantitatively similar bone formation compared to Caucasians. However, there was a significant increase of 2-3 fold in markers of bone formation and resorption in both groups. Therefore, it is currently not known whether the loss in BMD during lactation will be the same for both races. Primary outcome measures in this study will include spine, hip and radius BMD by Dual X-Ray Absorbiometry (DXA)Scans during lactation (at 2,12 and 24 weeks postpartum or at weaning if prior to 24 weeks postpartum, and six months after weaning (+1 week). This longitudinal protocol will distinguish between two hypotheses. Either: a) as measured by BMD, bone loss in African-Americans during lactation will be equal to that in Caucasians, and skeletal recovery will be the same or possibly accelerated compared to Caucasians; or, b) African-Americans will be resistant to bone loss during lactation compared to Caucasians because of resistance to Parathyroid Hormone-related Protein (PTHrP).

Other Disorders of Bone Density and Structure
Endocrine; Complications

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: "Bone Density and Calcitropic Hormones During Lactation in African-American and Caucasian Women"

Resource links provided by NLM:

Further study details as provided by University of Pittsburgh:

Primary Outcome Measures:
  • Change from baseline in bone density measurements (BMD) [ Time Frame: Change from baseline in BMD at 2,12, 24 weeks postpartum, and six months after weaning. ]
    Primary outcome measures will include spine, hip and radius BMD by DXA at 2, 12, and 24 weeks post-partum and 6 months post-weaning.

Secondary Outcome Measures:
  • Change from baseline of bone metabolism measurements [ Time Frame: Change from baseline at 2, 12,and 24 weeks postpartum, and six months after weaning. ]
    Bone metabolism measurements include: markers of bone turnover including calcium metabolic parameters such as calcium, phosphorus, fractional excretion of calcium, PTH(1-84), PTHrP, vitamin D metabolites, estradiol, sex hormone binding globulin (SHBG), prolactin, and breast milk calcium levels.

Biospecimen Retention:   Samples Without DNA
Blood and breast milk

Enrollment: 77
Study Start Date: August 2012
Study Completion Date: September 2015
Primary Completion Date: September 2015 (Final data collection date for primary outcome measure)
African-American Lactating Women
Healthy African-American women who are exclusively breast-feeding.
Caucasian Lactating Women
Healthy Caucasian women who are exclusively breast-feeding.

  Show Detailed Description


Ages Eligible for Study:   21 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
New mothers will be recruited from UPMC hospital population, primarily Magee Womens Hospital. As this is a study which aims to describe racial differences in bone metabolism during lactation in African-Americans and Caucasians, subjects must identify themselves as belonging to one of these groups.

Inclusion Criteria:

  • 21-45 years old
  • Post-partum after a singleton pregnancy
  • Exclusively breast-feeding (not more than one supplemental bottle of formula per day)
  • African-American or Caucasian by self-identification

Exclusion Criteria:

  • Subjects with cardiac, hypertensive, vascular, renal (serum creatinine of >1.5), pulmonary, endocrine, musculoskeletal, hepatic, hematologic, malignant or rheumatologic disease
  • Fractures or bone surgery within the past 12 months
  • Smokers and subjects with history of significant alcohol or drug use
  • Pregnant women
  • Women who achieved pregnancies with IVF or other hormonal manipulation
  • Women who had significant complications with the most recent pregnancy or who are unable to exclusively breastfeed beginning at birth
  • Subjects on chronic medications other than
  • stable doses of thyroid hormone
  • oral contraceptives
  • vitamin supplements
  • Women on Depo-Provera will be excluded
  • Receiving an investigational drug within 90 days
  • Weight greater than 130 kg
  • Z-score -3.0 or less (hip or spine) on initial DXA
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01630629

United States, Pennsylvania
University of Pittsburgh Medical Center
Pittsburgh, Pennsylvania, United States, 15213
Sponsors and Collaborators
University of Pittsburgh
Principal Investigator: Mara Horwitz University of Pittsburgh
  More Information

Additional Information:

Responsible Party: Mara Horwitz, Associate Professor of Medicine, University of Pittsburgh Identifier: NCT01630629     History of Changes
Other Study ID Numbers: PRO12050600
Study First Received: June 20, 2012
Last Updated: June 15, 2016
Individual Participant Data  
Plan to Share IPD: No

Keywords provided by University of Pittsburgh:
Bone Density
Physiological Properties
Bone Metabolism

Additional relevant MeSH terms:
Bone Diseases
Musculoskeletal Diseases processed this record on April 21, 2017