Abstract: In order to understand the risk factors of IDA in the second trimester of pregnancy,a case-control study with two kinds of controls was conducted with 528 pregnant women of which 152 case were diagnosised IDA.The non-conditional logistic regression analysis showed that the following significant risk factors were month of the end menstruation,intake of meat,poultry,fish and other sea products,parity,memorrhagia before pregnancy and cooking pot,which were associated with IDA during the second trimester of pregnancy.