The sudden absence of breast swelling and pain in early pregnancy is usually a normal physiological phenomenon, so there is no need to be too nervous, but it does not exclude the sudden disappearance of breast swelling and pain due to fetal arrest, so you can go to the hospital to check the ultrasound to see if the fetal heart and fetal buds are normal. Common causes and treatments 1, normal physiological phenomenon: after pregnancy, estrogen levels increase significantly, which in turn promotes the development of breasts and glandular ducts, more sensitive pregnant women will therefore feel breast swelling and pain, but with the development of pregnancy, the body gradually adapt to estrogen changes, thus leading to the disappearance of breast swelling and pain, as long as there is no vaginal bleeding or combined with stomach pain at the same time as the swelling and pain, there is generally no problem. 2.Fetal abortion: after the hormone level drops after embryonic abortion, the feeling of breast swelling and pain may disappear, along with the disappearance may also have early pregnancy gastrointestinal reactions, such as nausea, vomiting, etc. At this time, ultrasound examination can be done to clarify whether the fetal heartbeat and fetal bud are normal, and if necessary, blood can be drawn for HCG test to assess whether it is normal according to the doubling of HCG and comparing with the reference range of the same pregnancy week. If the diagnosis of embryonic abortion is confirmed, it is recommended to terminate the pregnancy by abortion or medication abortion, and if possible, it is better to have the aborted embryos examined for chromosomal examination to find the cause of the abortion. The fetus is not growing at a particularly fast rate, so there is no need to enhance nutrition too much. A normal diet can achieve the nutrients needed for fetal growth.