There are two main reasons why eating bird’s nest may cause precocious puberty in children: 1. If children eat a lot of bird’s nest for a long time, it will cause an increase of estrogen level in their body, resulting in precocious puberty. 2. The nutritional value of bird’s nest is very high, which can easily cause children’s overnutrition and obesity. The main reason for obesity is fat, which is converted into part of estrogen, which can also cause precocious sexual maturity.