The general situation is about 8 weeks of pregnancy when the germ is 17mm, which may vary slightly depending on individual circumstances. For women who usually have irregular menstrual cycles, the estimation of pregnancy time based on the last menstrual period may have a large error. The gestational week can be roughly calculated based on the size of the fetal bud in the ultrasound test result, the formula is fetal bud (cm) + 6.5 as the gestational week, according to the formula, the fetal bud is about 8 weeks of pregnancy when 17mm. Since the development of the embryo is related to the genetic and personal condition of the parents, the germ may be large or small, but it is usually normal, as long as the development is normal. The most accurate way to determine the gestational age is to measure the head and hips of the fetus at 11-13 weeks + 6 days of pregnancy. At 8 weeks of pregnancy, the embryo has already taken shape, but the placenta has not yet formed, so it is still a dangerous period. At this time, pregnant women need to pay attention to rest, avoid strenuous activities or heavy physical labor, follow the doctor’s instructions to take appropriate amounts of folic acid to prevent fetal neural tube malformations, pay attention to the diet to supplement nutrition, can be appropriate to eat more fish, shrimp, lean meat and eggs and milk food, avoid spicy stimulation.