AMAMENTAÇÃO PROTEGE MULHER da ARTRITE REUMATÓIDE ?

Amamentação e Artrite

Mulheres que amamentam têm menor risco de desenvolver artrite reumatóide, mesmo décadas depois de terem amamentado. E tem mais.De acordo com estudo do Brigham and Womens Hospital, dos Estados Unidos, que acompanhou a saúde de mais de 120 mil mulheres desde 1976, quanto mais tempo dura a amamentação, menores ficam os riscos.A descoberta foi publicada na última edição da revista Arthritis & Rheumatism. A artrite reumatóide afeta muito mais mulheres do que homens. Por conta disso, alguns cientistas defendem a teoria de que os hormônios masculinos, de alguma forma, são a resposta para explicar essa diferença.

A autora do estudo, Elizabeth W. Karlson, achava que iria descobrir que a amamentação aumentava os riscos para o desenvolvimento da doença, baseada na teoria do hormônio prolactina – aumentado em mulheres que estão amamentando – serviria como um gatilho para desencadear a artrite. Os resultados, entretanto, mostraram o oposto.
Entre as mulheres estudadas, aquelas que afirmaram ter amamentado por um período de 13 a 23 meses tiveram 20% menos  de chances de desenvolver a doença do que as que não haviam amamentado. As que amamentaram por pelo menos  2 anos tiveram o risco reduzido pela metade. A pesquisa  mostrou também que mulheres de 30 a 35 anos com ciclos menstruais irregulares tinham chances aumentadas de desenvolver a doença na terceira idade.

Estudo abaixo:

Research Article

Do breast-feeding and other reproductive factors
influence future risk of rheumatoid arthritis?:
Results from the Nurses Health Study

Elizabeth W. Karlson 1 *, Lisa A. Mandl 2, Susan E.
Hankinson 1, Francine Grodstein 1

   
1Brigham and Womens Hospital, Harvard Medical School, and Harvard School of Public Health, Boston, Massachusetts
2Hospital for Special Surgery, Cornell Weill Medical College, New York, New York
    
email: Elizabeth W. Karlson (ekarlson@partners.org)    

*Correspondence to Elizabeth W. Karlson, 75 Francis
Street, Boston, MA 02115

Funded by:
NIH; Grant Number: K08-AR-02074-1, AR-47782,
AR-36308, CA-87969
Arthritis Foundation Investigator award
American College of Rheumatology Clinician
Investigator award

Abstract

Objective    
To explore the contribution of female hormonal factors occurring prior to the onset of rheumatoid arthritis (RA), such as age at menarche, parity, age at first birth, breast-feeding, use of oral contraceptives (OCs), irregular menstrual cycles, and postmenopausal hormone (PMH) use, to the subsequent development of RA in a large female cohort.    

Methods    
We studied female reproductive and hormonal risk
factors for RA in a cohort of 121,700 women enrolled in the longitudinal Nurses Health Study. The diagnosis of incident RA (between 1976 and 2002)in 674 women was confirmed by a connective tissue disease screening questionnaire and blinded medical record review for American College of Rheumatology criteria.
Sixty percent of the patients with RA were rheumatoid factor positive. The relationship between potential risk factors, including age, age at menarche, parity, age at first birth, total lifetime history of breast-feeding, use of OCs, and irregular menstrual cycles and the multivariate-adjusted risk of RA was estimated using Cox proportional hazards models.    

Results    
Using a multivariate model that adjusted for age, body mass index, smoking, parity, and other hormonal factors, we observed a strong trend for decreasing risk of RA with increasing duration of breast-feeding (P for trend = 0.001). For women who breast-fed (compared with parous women who did not breast-feed), the risk ratios (RRs) and 95% confidence intervals (95% CIs) were as follows: breast-feeding for 3 total months, RR 1.0 (95% confidence interval [95% CI] 0.8-1.2); for 4-11 total months, RR 0.9 (95% CI 0.7-1.1); for 12-23 total months, RR 0.8 (95% CI 0.6-1.0); and for 24 total months, RR 0.5 (95% CI 0.3-0.8). Very irregular menstrual cycles were associated with an increased risk of RA (RR 1.4, 95% CI 1.0-2.0). Age at menarche 10 years was associated with an increased risk of seropositive RA (RR 1.6, 95%
CI 1.1-2.4) but not significantly associated with risk of RA. Parity, total number of children, age at first birth, and OC use were not associated with an increased risk of RA in this cohort.    

Conclusion    
In this large cohort, breast-feeding for >12 months
was inversely related to the development of RA. This apparent effect was dose-dependent, with a significant trend toward lower risk with longer duration of breast-feeding. Irregular menstrual cycles and earlier age at menarche increased the risk of RA. Other reproductive hormonal factors were not associated with RA risk.    

Received: 17 December 2003; Accepted: 10 August 2004