The development of the fetus at 31 weeks varies from one baby to another due to various factors. Usually, the development of the fetus at 31 weeks is about 1600g to 2000g, the average biparietal diameter is about 8.06±0.60cm, and the fetus can see and hear and breathe on its own during this period. As the baby continues to grow, the space in the uterus gradually becomes smaller, so the fetal movement is less than before. For 31 weeks pregnant mothers due to the increase of the uterus, they should control their diet in moderation to prevent the fetus from being too big to affect the delivery. They can eat more high quality protein food, such as fish and shrimp food, and also eat more fresh vegetables and fruits. In addition, the weight of the fetus on the birth certificate is only an approximate reference indicator, the actual birth weight of the fetus sometimes varies, and it is not always accurate to guess the size of the fetus based on the size of the pregnant woman’s belly, because some pregnant women’s belly is large does not necessarily mean that the baby’s weight is large, some may be more amniotic fluid or the pregnant woman’s belly fat, the actual birth of the fetus may not be heavier than the pregnant mother whose belly looks smaller. The actual baby delivered may not necessarily be heavier than the baby delivered by a pregnant woman with a smaller belly. In short, as long as the indicators in the maternity checkup are probably normal or within the reference range, don’t worry, regular maternity checkups are fine, but be prepared for an early delivery.