In the third trimester of pregnancy, around 12 weeks, the baby is usually 9-10cm long and weighs around 20g. During the third trimester the baby is already differentiated and the baby’s limbs, thorax, and head can be distinguished, and the sex organs have also started to develop at this time. This time period can be roughly judged by the sex organs is gender, but because the development of sex organs is still relatively small, so the accuracy is not high. Fetal development in the third trimester of pregnancy gradually increases, and the mother’s uterus also increases in size, like the size of a fist, and the uterus is about 1cm above the pubic bone union. An inconspicuous slight bulge begins to form in the abdomen and the pregnant woman may feel a sense of pressure in her lower abdomen. If the baby’s weight deviates from the normal range when the pregnant woman is in her third trimester of pregnancy, it is recommended that she seek medical attention in time, under the guidance of the doctor, improve the relevant examinations, clarify the cause of the disease and treat the symptoms.