Low heart rate in newborns is mostly seen in hypoxia and congenital hypothyroidism. 1. Hypoxia: It may be due to the fact that hypoxia exists in the fetus in the mother’s body, which can easily cause low heart rate. It is also possible that hypoxia occurs during the viability period, for example, when the umbilical cord is wrapped around the neck or the duration of labor is too long, which may also lead to low heart rate in newborns. 2. Congenital hypothyroidism: the incidence of this disease is relatively high, the child will often have insufficient secretion of thyroid hormone, catecholamine sensitivity will also be reduced, resulting in low heart rate. Low heart rate in newborns may also be caused by other reasons, and it is recommended to go to the hospital in time to find out the cause and actively treat it if necessary.