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Long-Term Breast-Feeding May Reduce Risk for Rheumatoid Arthritis

  • Authors: News Author: Laurie Barclay, MD
    CME Author: Charles Vega, MD
  • CME Released: 5/14/2008
  • Valid for credit through: 5/14/2009
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Target Audience and Goal Statement

This article is intended for primary care clinicians, obstetrician-gynecologists, rheumatologists, and other specialists who care for patients at risk for incident RA.

The goal of this activity is to provide medical news to primary care clinicians and other healthcare professionals in order to enhance patient care.

Upon completion of this activity, participants will be able to:

  1. Describe the role of gender and pregnancy on the prevalence and symptoms of RA.
  2. Identify the effects of breast-feeding and OCs on the incidence of RA.


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  • Laurie Barclay, MD

    Laurie Barclay, MD is a freelance reviewer and writer for Medscape.


    Disclosure: Laurie Barclay, MD, has disclosed no relevant financial relationships.


  • Brande Nicole Martin

    Brande Nicole Martin is the News CME editor for Medscape Medical News.


    Disclosure: Brande Nicole Martin has disclosed no relevant financial information.

CME Author(s)

  • Charles P Vega, MD

    Associate Professor; Residency Director, Department of Family Medicine, University of California, Irvine


    Disclosure: Charles Vega, MD, has disclosed an advisor/consultant relationship to Novartis, Inc.

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Long-Term Breast-Feeding May Reduce Risk for Rheumatoid Arthritis

Authors: News Author: Laurie Barclay, MD CME Author: Charles Vega, MDFaculty and Disclosures

CME Released: 5/14/2008

Valid for credit through: 5/14/2009


May 14, 2008 — Women who breast-fed for more than 1 year had a lower risk for rheumatoid arthritis (RA), according to the results of a study reported in the May 13 issue of Annals of the Rheumatic Diseases.

"Previous studies have suggested that extended breast feeding is associated with a reduced risk of future onset of RA," write M. Pikwer, from Malmö University Hospital in Malmö, Sweden, and colleagues. "The underlying mechanisms are unknown, and there is limited information on the relative effect of breast feeding and other suggested predictors of RA, such as smoking and low level of formal education."

The purpose of this community-based, prospective cohort study was to assess whether breast-feeding or the use of oral contraceptives (OCs) was associated with future risk for RA.

A community-based health survey of 18,326 women was linked to regional and national registers, allowing identification of incident cases of RA. A case-control study compared all women with a diagnosis of RA after inclusion in the health survey (n = 136) with 4 age-matched female control patients for every case patient, who were alive and free from RA when the index person was diagnosed with RA (n = 544). A self-administered questionnaire provided data on lifestyle factors at baseline, and logistic regression models examined potential predictors for RA.

A longer history of breast-feeding was linked to a lower risk for RA. Compared with women who had never breast-fed, the odds ratio for RA was 0.46 (95% confidence interval [CI], 0.24 - 0.91) for women who had breast-fed for more than 13 months and 0.74 (95% CI, 0.45 - 1.20) for those women who had breast-fed for 1 to 12 months. Adjustment for smoking and level of education did not abolish the protective effect of longer breast-feeding, nor did restricting the analyses to parous women. Neither parity nor OC use was significantly associated with risk for RA.

Limitations of this study include the relatively low number of case patients, especially in subgroup analysis of parous women; that the number of women who gave birth but did not breastfeed was too small for a reliable estimate of their risk compared with nulliparous women; that the data were limited to women with onset of RA in their 40s or older; an inability to determine the short-term effect of breast-feeding; and possible unmeasured confounders.

"Our data show a decreased risk of RA in postmenopausal women with a history of long-term breast feeding," the study authors write. "The effect was dose-dependent and remained significant after adjustment for smoking and level of education."

The Craaford Foundation and the Swedish Rheumatism Association supported this study. The authors have disclosed no relevant financial relationships.

Ann Rheum Dis. Published online May 13, 2008.

Clinical Context

RA is approximately twice as common among women compared with men, and the increased prevalence among women is most notable during the reproductive years, when the female-to-male ratio of RA is 5:1. Women who become pregnant frequently experience an improvement in the symptoms of RA, but these symptoms frequently flare during the postpartum period. The issue of whether OCs have an effect on the symptoms of RA remains controversial.

Some research has suggested that breast-feeding may reduce the risk for incident RA. The current prospective cohort study focuses on this subject.

Study Highlights

  • The study cohort was drawn from the Malmö Diet and Cancer Study, which included 30,477 subjects between the ages of 44 and 74 years.
  • All participants gave baseline health data, including data regarding the use of OC and the duration (if any) of breast-feeding.
  • A community-based register was used to identify cases of RA, which were then verified in the medical record.
  • The main study outcomes were the relationships between breast-feeding, OC use, and incident RA. These outcomes were adjusted for potential confounders, including smoking, level of education, and parity.
  • 18,326 participants in the study were female. The follow-up duration for the cohort was 188,969 person-years.
  • 136 women were identified with incident RA. The mean age at the onset of RA was 63.3 years.
  • These women were compared with 544 age-matched controls without RA.
  • Smoking and OC use had no significant effect on the risk for incident RA.
  • There was a nonsignificant trend toward a reduced risk for RA with each child born.
  • Compared with women who had not breast-fed, women who breast-fed for at least 13 months experienced an odds ratio of 0.46 for incident RA. The respective odds ratio for women who breast-fed for 1 to 12 months was 0.74, which was not statistically significant.
  • Breast-feeding was particularly protective against incident RA that was rheumatoid factor-negative. The effects of breast-feeding on the risk for incident RA were similar to those of the general study population when examining only parous women in the study cohort.


Pearls for Practice

  • RA is twice as common among women compared with men, and 5 times as many women are diagnosed with RA during the childbearing years compared with men of a similar age. RA symptoms are frequently ameliorated during pregnancy, but postpartum RA flares are also common.
  • The current study suggests that breast-feeding for at least 13 months is associated with a reduced risk for RA.

CME Test