Multivitamin supplementation compared with no multivitamins significantly lowered women 's risk of presumptively diagnosed clinical malaria ( relative risk : 0.78 , 95 % confidence interval : 0.67 to 0.92 ) , although multivitamins increased their risk of any malaria parasitemia ( relative risk : 1.24 , 95 % confidence interval : 1.02 to 1.50 ) .