Usually, it may be normal for the fetus to move a few times like twitching in 39 weeks of pregnancy, or it may be caused by calcium deficiency. Generally refers to the late pregnancy due to the fetus has matured, fetal strength is greater, and thus the amplitude of fetal movement will be greater, so the fetus will be like trembling twitching. Pregnant women are more prone to calcium deficiency during pregnancy, so it is also more likely to cause calcium deficiency in the fetus. This phenomenon can occur when calcium ions in the blood of the fetal organism decrease, neuromuscular excitability increases, and skeletal muscle cells become abnormal in stretching and diastolic activity. In addition, it is recommended that pregnant women whose fetus moves a few times like a twitch in the 39th week of pregnancy go to the hospital in time to avoid delaying their condition.