my son started 打"C EGG" when few days old..the reg nurse in health clinic told me that it is normal..because some systems of new born baby's body are still developing... for example:digestive system..and she also said babies打"C EGG"are not very uncomfortable as adult...it will disappear after a while or after crying, etc
by the way,my baby sometimes 打"C EGG" but it disappear very soon