Normally a single fetus in the 2nd month of pregnancy does not become a twin. Twin fetuses may occur when two eggs are fertilized separately to form two fertilized eggs that are implanted in the uterine lining, or when one egg and sperm combine to form a single fertilized egg, but the fertilized egg splits into two embryos early in its development to form a twin fetus. These are determined early in the pregnancy and will not turn a single fetus into a twin in the 2nd trimester. Early pregnancy should pay attention to rest, do not do strenuous exercise, avoid staying up late, coitus, heavy physical activity. During pregnancy, you should also pay attention to strengthening nutrition, so as to achieve a diversified diet, meat and vegetables, a reasonable diet. Pay attention to regular obstetric examination, observe the development of the fetus, if there is any abnormality, timely medical treatment, under the guidance of the doctor to deal with.