OBJECTIVE: To assess the potential role of allo-immunization, either by former pregnancies, or by a history of blood transfusion, in the pathogenesis of giant cell arteritis and polymyalgia rheumatica. METHODS: Two hundred and eighty-five incident female cases and 186 age-matched, population-based female controls were prospectively included in a multicentre case-control study. RESULTS: The number of pregnancies was significantly lower in cases than in controls (nulliparous: 21.55% vs 12.90%; > or =4 pregnancies: 16.25% vs 27.42%; Wilcoxon rank sum test: P = 0.0019) in biopsy-proven or negative temporal arteritis and, to a lesser extent, in polymyalgia rheumatica. No difference was found for history of blood transfusion. Pregnancies remained negatively associated with the disease in a multivariate analysis including cardiovascular risk factors such as smoking or a pre-existing peripheral vascular disease. CONCLUSION: Former pregnancies are not a risk factor for giant cell arteritis. Pregnancies may be protective thanks to an effect of the associated hyperoestrogenic state against alterations of the artery wall, as suggested in animal models.
OBJECTIVE: To assess the potential role of allo-immunization, either by former pregnancies, or by a history of blood transfusion, in the pathogenesis of giant cell arteritis and polymyalgia rheumatica. METHODS: Two hundred and eighty-five incident female cases and 186 age-matched, population-based female controls were prospectively included in a multicentre case-control study. RESULTS: The number of pregnancies was significantly lower in cases than in controls (nulliparous: 21.55% vs 12.90%; > or =4 pregnancies: 16.25% vs 27.42%; Wilcoxon rank sum test: P = 0.0019) in biopsy-proven or negative temporal arteritis and, to a lesser extent, in polymyalgia rheumatica. No difference was found for history of blood transfusion. Pregnancies remained negatively associated with the disease in a multivariate analysis including cardiovascular risk factors such as smoking or a pre-existing peripheral vascular disease. CONCLUSION: Former pregnancies are not a risk factor for giant cell arteritis. Pregnancies may be protective thanks to an effect of the associated hyperoestrogenic state against alterations of the artery wall, as suggested in animal models.