Fetal femur length of 45mm at 27 weeks of pregnancy is usually normal and varies due to individual differences. When a woman is 27 weeks pregnant, the fetal femur length is about 52mm, and the measured fetal femur length of 45mm is on the short side, but it is usually normal, which may be caused by the actual number of days of pregnancy being late, or may be caused by insufficient nutritional intake of the pregnant woman or the parents’ own height being on the short side. During pregnancy, you should strengthen your nutritional intake, eat more fresh fruits and vegetables and lean meat, and take some calcium supplements to promote fetal growth and development. At the same time, you also need to take regular pregnancy tests to observe the condition of the fetus, and if there is any abnormality, it should be dealt with in time. Therefore, 27 weeks pregnant fetal femur length of 45mm is generally normal, it is recommended that pregnant women maintain a good mood, avoid too much tension, learn to regulate bad mood, so as not to affect the health.