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Oral contraceptives may reduce or increase vitamin D

Connection?: Contraceptives ==> reduce bleeding ==> less anemia ==> increased Vitamin D

Gradual bone reduction seen in some pill users July 2011

Changes in bone density in oral contraceptive users depends on age and hormone dose

SEATTLE, WA — Birth control pills may reduce a woman's bone density, according to a study published online July 13 in The Journal of Clinical Endocrinology and Metabolism by Group Health Research Institute (GHRI) scientists. Impacts on bone were small, depended on the woman's age and the pill's hormone dose, and did not appear until about two years of use. The study size and design allowed the researchers to focus on 14- to 18-year-old teenagers, and to look at how bone density might change when a woman stops using the pill.

GHRI Senior Investigator Delia Scholes, PhD, led the study. Hormones are a key component of bone health, she says, and hormonal contraceptives are a major source of external hormones for women—the pill is the most common birth control method worldwide. A woman's risk of fractures later in life is influenced by the bone mass she gains in her teens through her 20s, and this age group has the highest use of oral contraceptives. "The teen years are when women most actively gain bone, so we thought it was important to look at that age group," says Scholes. "We found that oral contraceptive use had a small negative impact on bone gain at these ages, but took time to appear, and depended on hormone dose."

The researchers measured hip, spine, and whole-body bone densities in 301 teen women aged 14-18, and in 305 young adult women aged 19-30, all Group Health Cooperative members. The bone densities of 389 participants using oral contraceptives were compared to 217 similar women who were not using this method, looking at both teens and young adults, and the two most commonly prescribed estrogen doses in pills: 20-25 micrograms and 30-35 micrograms. Bone density measurements were taken at the start of the study, and every 6 months for 2 to 3 years. During that time, 172 oral contraceptive users stopped taking the medication, allowing the researchers to measure bone changes after pill use was discontinued. They found:

  • After two years, teens who used 30-35 microgram pills showed about 1% less gain in bone density at both the spine and whole body sites than teens who did not use hormonal contraceptives.
  • For young adult women, users and non-users of oral contraceptives showed no differences in bone density at any site.
  • Any differences in bone density between users and nonusers of oral contraceptives were less than 2%, and were seen only after two or more years of use, and only at some measured sites.
  • At 12-24 months after stopping, teens who took 30-35 microgram pills still showed smaller bone density gains at the spine than teens who did not use oral contraceptives.
  • At 12-24 months after stopping, young adult women who used either pill dose showed small bone density losses at the spine compared to small gains in women who did not take oral contraceptives.

Scholes says additional studies, including looking at bone changes for a longer time after pill use is discontinued, may tell us more about how oral contraceptive use is related to fracture risk. For now, the results of Scholes' study may help women make informed decisions. "Bone health, especially for long-term users of the pill, may be one of many factors women consider in choosing a contraceptive method that's right for them," she says. The US Surgeon General recommends that women maintain bone density by eating foods high in calcium and vitamin D, getting weight-bearing exercise, not smoking, and limiting drinking alcohol.

Dr. Scholes' co-authors are Rebecca A. Hubbard, PhD, Laura E. Ichikawa, MS, and Leslie Spangler VMD, PhD, Group Health Research Institute (GHRI); Andrea Z. LaCroix, PhD, MPH, and Jeannette M. Beasley, PhD, MPH, RD, Women's Health Initiative, Fred Hutchinson Cancer Research Center, Seattle WA; Susan Reed, MD, MPH, Department of Obstetrics and Gynecology, University of Washington, Seattle, WA (UW); and Susan M. Ott, MD, Department of Medicine, UW. Funding was from the Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health.

Group Health Research Institute: Founded in 1947, Group Health Cooperative is a Seattle-based, consumer-governed, nonprofit health care system. Group Health Research Institute changed its name from Group Health Center for Health Studies in 2009. Since 1983, the Institute has conducted nonproprietary public-interest research on preventing, diagnosing, and treating major health problems. Government and private research grants provide its main funding.
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Steroidal contraceptives: effect on bone fractures in women.

Cochrane Database Syst Rev. 2011 Jul 6;(7):CD006033.
Lopez LM, Grimes DA, Schulz KF, Curtis KM.
Clinical Sciences, FHI, P.O. Box 13950, Research Triangle Park, North Carolina, USA, 27709.

Steroidal contraceptive use has been associated with changes in bone mineral density in women. Whether such changes increase the risk of fractures later in life is not clear. Osteoporosis is a major public health concern. Age-related decline in bone mass increases the risk of fracture, especially of the spine, hip, and wrist. Concern about bone health influences the recommendation and use of these effective contraceptives globally.

To evaluate the effect of using hormonal contraceptives before menopause on the risk of fracture in women

We searched for studies of fracture or bone health and hormonal contraceptives in MEDLINE, POPLINE, CENTRAL, EMBASE, and LILACS, as well as ClinicalTrials.gov and ICTRP. We wrote to investigators to find additional trials.

Randomized controlled trials (RCTs) were considered if they examined fractures, bone mineral density (BMD), or bone turnover in women with hormonal contraceptive use prior to menopause. Interventions could include comparing a hormonal contraceptive with a placebo or another hormonal contraceptive or could compare providing a supplement versus a placebo.

We assessed all titles and abstracts identified through the literature searches. Mean differences were computed using the inverse variance approach. For dichotomous outcomes, the Mantel-Haenszel odds ratio (OR) was calculated. Both included the 95% confidence interval (CI) and used a fixed-effect model. Due to different interventions, no trials could be combined for meta-analysis.

Of the 16 RCTs we found, 2 used a placebo and 1 used a non-hormonal method as the comparison, while 13 compared two hormonal contraceptives. No trial had fracture as an outcome. Most measured BMD and several assessed bone turnover. Depot medroxyprogesterone acetate (DMPA) was associated with decreased bone mineral density. The placebo-controlled trials showed BMD increases for DMPA plus estrogen supplement and decreases for DMPA plus placebo. Combination contraceptives did not appear to negatively affect bone health, but none were placebo-controlled. For implants, the single-rod etonogestrel group showed a greater BMD decrease versus the two-rod levonorgestrel group. However, results were not consistent across all implant comparisons.

Whether steroidal contraceptives influence fracture risk cannot be determined from existing information. Many trials had small numbers of participants and some had large losses to follow up. Health care providers and women should consider the costs and benefits of these effective contraceptives. For example, injectable contraceptives and implants provide effective, long-term birth control yet do not involve a daily regimen. Progestin-only contraceptives are considered appropriate for women who should avoid estrogen due to medical conditions.
Update of Cochrane Database Syst Rev. 2009;(2):CD006033. PMID: 21735401
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Impact of combined and progestogen-only contraceptives on bone mineral density.- 2009

Joint Bone Spine. 2009 Mar;76(2):134-8. Epub 2009 Feb 1.
Sarfati J, de Vernejoul MC.
INSERM U606, Hôpital Lariboisière 2 rue Ambroise Paré, 75010 Paris, France.

Sex steroids are major determinants of bone mass, and hormonal contraceptives may affect bone mineral density (BMD) in women. Combination contraceptives probably have no impact on BMD, except perhaps when started within 3 years after the menarche. Progestogen-only contraceptives are being increasingly used. Injectable medroxyprogesterone acetate, a potent inhibitor of gonadotropin release, can induce bone loss, most notably in young women. Other progestogens are used in lower doses that have weaker antigonadotropin effects. Levonorgestrel and etonorgestrel implants have unclear effects on BMD but are probably safe. The impact of high- and low-dose oral progestogens on BMD has not been investigated, although no adverse effects would be expected.

PMID: 19181558

Estrogen-Containing Contraception associated with 20% higher vitamin D levels - 2016

Use of Estrogen-Containing Contraception Is Associated With Increased Concentrations of 25-Hydroxy Vitamin D
Journal of Clinical Endocrinology & Metabolism. DOI: http://dx.doi.org/10.1210/jc.2016-1658 Published Online: August 04, 2016
Quaker E. Harmon quaker.harmon at nih.gov., David M. Umbach, and Donna D. Baird

Context: Small studies suggest exogenous estrogen may improve vitamin D status, but the etiology is unclear because women who use hormones may make lifestyle choices that differentially affect vitamin D status.

Objective: Our objective was to investigate the association between use of hormonal contraception and 25-hydroxy-vitamin D (25(OH)D).

Design: We used linear regression modeling of cross-sectional data to estimate percent change in season-adjusted serum 25(OH)D with estrogen use after adjustment for other factors.

Setting: At the enrollment clinic visit (2010–2012) into a cohort study of uterine fibroids, each subject provided a blood sample, had anthropomorphic variables and skin reflectance measured, and answered questionnaires on demographics, dietary and supplement intake, contraceptive use, reproductive and medical history, and behaviors.

Participants: A total of 1662 African American women, community volunteers, 23–34 years old, living in the Detroit, Michigan, area were included.
Interventions: None.

Main Outcomes and Measures: Serum 25(OH)D was measured.

Results: Serum 25(OH)D concentrations were low (70% <20 ng/ml). Current use of an estrogen-containing contraceptive was associated with a 20% (95% confidence interval: 14–27) increase in 25(OH)D after adjustment. There was no increase in 25(OH)D among participants who had used estrogen in the past, but were not current users, indicating that results were unlikely to be due to unmeasured confounding by factors related to contraceptive choice.

Conclusions: The increase in 25(OH)D with use of estrogen-containing contraceptives raise mechanistic questions regarding the biological pathways involved, and highlights the need for studies that examine possible endogenous estrogen effects on vitamin D.

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Contraceptives do not seen to reduce bone very much: only 1 to 2% less growth

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