Background: Maternal mortality rate (MMR) and infant mortality rate (IMR) is one of indicator to determine the degree of community health. Anemia is a problem in pregnant women as a result of iron deficiency and body folic acid. A high incidence of anemia is a factor in the high incidence of LBW. In the second trimester of pregnancy the growth and development of the baby increases rapidly so the mother will need more nutrition. In the third trimester of pregnancy, to meet the needs of fetal growth and development and avoid complications of childbirth, adequate nutrition is needed for pregnant women. Prevention of anemia in pregnant women is believed to reduce the incidence of LBW and is able to reduce maternal and infant morbidity and mortality Method: A non-experimental research with a case control design and chi-square statistical test using secondary data medical records. The sample is a population that meets the inclusion criteria and regardless of the exclusion criteria as many as 64 pregnant woman who control or give birth at the Tegalrejo Health Center Yogyakarta. Results: The results of the bivariate analysis showed that anemia in pregnant women in the second trimester had a significant relation with the incidence of LBW obtained p value = 0,010 and OR = 4,2 [CI 95% 1,478-11,936]. Whereas for anemia in pregnant women in the third trimester did not have a significant relation with the incidence of LBW obtained p value = 0,617 and OR = 1,284 [CI 95% 0,481-3,429]. Conclusions: There was a significant association between anemia in pregnant women in second trimester with the incidence of LBW. There was no significant association between anemia in pregnant women in the third trimester and the incidence of LBW.