The development of the fetus can usually be initially observed through ultrasound examination at 40-50 days after pregnancy. After a woman is pregnant, it usually takes about 7 days for the gestational sac to come to bed, and then the gestational sac starts to develop and differentiate. On about 40 days of pregnancy, the gestational sac can be observed through ultrasound to determine whether it is an intrauterine pregnancy, so as to exclude ectopic pregnancy, gravida and other abnormalities, and after 45 days of pregnancy, the germ and heart of the fetus can be determined through ultrasound for any abnormalities. In the early stage of pregnancy, pregnant women should have regular maternity checkups and take folic acid according to medical advice, which can effectively prevent neural tube abnormalities in the fetus and facilitate the healthy growth of the fetus. In the first three months of pregnancy, sexual intercourse should be forbidden to avoid adverse consequences such as pre-eclampsia miscarriage. In the early stage of pregnancy, the fetus is unstable, pregnant women should pay attention to rest, avoid strain, stay up late, eat more fresh vegetables and fruits, supplement protein and vitamins, to achieve a reasonable diet and balanced nutrition. At the same time, pregnant women should ensure a relaxed mood, not anxiety, fire, pay attention to personal hygiene, to avoid infection.