At 16 weeks of gestation, the fetus has entered a period of rapid development, the fetus weighs about 150g, the development of the head, bones and abdominal organs has already appeared, and the growth of the fetus is clearly visible under ultrasound examination. The length of the fetus’s legs exceeds that of the arms, and the hands have begun to develop, with movement of the knuckles and complete fingernails. In addition, the fetal heart rate can reach 120-160 beats per minute, the reproductive organs are taking shape, and the sex of the fetus can be distinguished during the ultrasound examination. At 16 weeks of pregnancy, the physical condition of pregnant women is basically stable. During this period, pregnant women should pay attention to maintenance and supplement high-quality protein foods such as soybeans, lean meat, fish and soy products. In addition to the general prenatal checkups, the most important one is the Down syndrome screening, which is mainly used to check whether the fetus has chromosomal abnormalities.