When the biparietal diameter of the fetus is small, it means that the development of the fetus is slow, so you can adjust your diet and eat more protein and calcium-rich food to enhance nutrition and promote the development of the fetus. When the biparietal diameter of the fetus is small, it means that the fetus is malnourished. Pregnant women can adjust their diet to replenish nutrients for the body, promote the absorption of protein and calcium for the fetus, and promote the development of the biparietal diameter, and at this time, they can eat lean meat, chicken, milk and other foods, which are easy to absorb the protein and calcium. When the fetus has a small biparietal diameter, it is necessary to go to the hospital in time, and under the guidance of the doctor to take appropriate methods of intervention to promote the full development of the fetus. Pregnant women should also do relevant examinations to observe the growth and development of the fetus.