When the embryo is 15mm in size according to the color Doppler ultrasound, you should generally be more than 40 days pregnant, about 7 weeks pregnant. Around 7 weeks of pregnancy, the fetus is still relatively small, about 15mm in size, and the most that can be seen on examination is the fetal buds and the fetal heart. If the fertilized egg is deposited late, the fetal buds and the fetal heart may not be seen, and these are all normal situations, and it is recommended to go to the hospital after some time for a recheck to see if the fetus is developing normally. After pregnancy, pregnant women need to observe their physical symptoms. If symptoms such as bleeding or abdominal pain occur, it may be a case of pre-eclampsia, and they need to go to the hospital for timely consultation. At about 7 weeks of pregnancy, the embryo has not yet developed, and it is probably at about 12 weeks of pregnancy that the various organs of the body will slowly begin to form. During pregnancy, you should pay attention to rest, maintain a good mood, get enough sleep, eat more fresh vegetables and fruits, avoid abusing drugs, stay away from radiation, and go to the hospital regularly for pregnancy checkups, which are beneficial to both the pregnant woman and the fetus.