It is usually normal for a 30 week fetus to be around 3 pounds. The weight of the fetus is also related to genetics, the eating habits of the pregnant woman, and whether the pregnant woman is suffering from any illnesses. If both parents are short in stature, the weight of the fetus inside the body will usually be lighter compared to fetuses of the same age in the same month. On the contrary, the weight will be relatively heavier. Some pregnant women have serious early pregnancy reaction, which will seriously affect the appetite, resulting in reduced intake of nutrients, which will affect the growth and development of the fetus, compared with the same age of the fetus weight is a little lighter. On the other hand, excessive intake of nutrients by pregnant women will lead to overweight fetus. Pregnant women who suffer from gestational hypertension, diabetes mellitus, etc., usually have certain dietary restrictions during pregnancy, which may affect the growth and development of the fetus in the body, thus leading to light or heavy fetal weight. If the weight of the fetus at 30 weeks is significantly lower or higher than the above range, it is recommended to consult a doctor in time, under the guidance of the doctor, improve the relevant examinations, clarify the cause of the disease and treat the symptoms.