Babies with a birth weight of less than 3,000 grams reach puberty months earlier than other babies, and the earlier the puberty, the higher the chance of the child developing breast or testicular cancer in the future. Researchers therefore suggest that pregnant women should pay attention to nutritional balance during pregnancy. A long-term study shows that babies born with a birth weight of less than 3,000 grams reach puberty months earlier than other babies, and the earlier the puberty, the higher the chance that the child will develop breast or testicular cancer in the future. Researchers therefore suggest that pregnant women should pay attention to nutritional balance during pregnancy. The researchers believe that one of the reasons for the increasing number of underweight newborns in affluent countries is that some mothers have adopted dieting measures during pregnancy to avoid gaining too much weight. For this reason, they urge pregnant women to pay special attention to nutritional balance during pregnancy, and to understand that quitting smoking can also help prevent babies from being born underweight. Studies have shown that infants with a birth weight of less than 3,000 grams reach puberty an average of seven months earlier than the general population, and that girls have their first menstruation earlier. The timing of a girl’s first menstruation has a significant impact on the risk of breast cancer, and in principle, the later the risk, the lower the risk. Six months after the first menstruation, the risk of developing breast cancer in the future is reduced by 4% to 5%. Early puberty in boys, on the other hand, increases the risk of testicular cancer.