Pregnancy and motherhood are a wonderful happy experience for every woman. In order to have a healthy pregnancy, help the fetus develop well, avoid the risk of birth defects and properly care for th baby in the first years of life, the woman needs to be equipped with knowledge to reduce the rate of morbidity and mortality in children. Therefore, the study on knowledge of pregnant women about birth defects and some factors related to women's knowledge at Thai Nguyen National Hospital has been conducted. There are 390 pregnant women selected, the results in the study show that the knowledge of pregnant women on BDs at the average level accounts for the highest rate with 78.4%. There is a statistically significant difference between women's knowledge about BDs with occupation, age groups and education level, number of antenatal care visits, learned about BDs, and attending prenatal classes with p <0.05.