The normal range of alpha-fetoprotein in pregnancy is about 40-400ng/ml, if the alpha-fetoprotein is 251ng/ml at 22 weeks of pregnancy it is normal. The continuous growth and development of the fetus during pregnancy will cause the level of alpha-fetoprotein in the pregnant woman’s body to be higher than before pregnancy, and the range of alpha-fetoprotein during pregnancy is about 40-400ng/ml. if the alpha-fetoprotein is too low, it means that the fetus may have abnormalities, and if the alpha-fetoprotein is too high, it is also not normal. Therefore, a fetoprotein of 251ng/ml at 22 weeks of pregnancy is normal. The significance of monitoring of alpha-fetoprotein during pregnancy is to evaluate the growth and development of the fetus and to assess the risk of chromosomal abnormalities and fetal malformations. Pregnant women are advised to ask professional doctors to interpret the test results to ensure the state of fetal growth and development. In addition to the alpha-fetoprotein test, pregnant women are also advised to go to the hospital regularly for Down’s syndrome screening.