Frog legs refers to the natural bending of the baby’s legs at birth, similar to the capital M. The reasons for frog legs include two aspects, on the one hand, the mother’s late pregnancy, the space in the stomach is getting smaller and smaller, the baby can only take the bending position; on the other hand, the natural bending is a kind of self-protection, the position, the baby’s hip joint pressure is minimal, which is conducive to the growth and development of the hip joint. Therefore, if parents find that the baby’s legs have been in a bent state, the practice of straightening and tying their legs is not advisable. Parents should give the baby wear one-piece or sleeping bag clothes, so that its limbs naturally stretch.