Calcified spots do not always appear on the placenta in the second trimester of pregnancy. There are physiological reasons for the appearance of calcified spots, as well as reasons such as hyperemesis gravidarum or expired pregnancy. 1. Physiological reasons: under physiological circumstances, with the increase of pregnancy months, the fetus gradually develops and matures, a small amount of calcification may appear on the placenta, which will not affect the health of the fetus at this time. 2. Hyperemesis gravidarum: Hyperemesis gravidarum is the short form of hypertensive syndrome in pregnancy. When pregnant women have high blood pressure in pregnancy, it may lead to hardening or even rupture of the placental blood vessels, which may lead to focal infarction of the placenta, and the ultrasound will show the appearance of calcified spots. 3. Expired pregnancy: when pregnant women have expired pregnancy, due to the deterioration of the vascular status of the placental tissue, local ischemic necrosis may occur, and calcification points may also appear. Pregnant women with placental calcification are advised to consult a doctor in time to improve the examination to determine the type of placental calcification, and take reasonable measures to intervene under the guidance of the doctor.