If the pregnant mother often stay up late for a long time on the fetus may cause fetal dysplasia, fetal irritability after birth and other effects, once in a while to stay up late generally does not affect the fetus, do not be too nervous. 1. Fetal dysplasia: Pregnant mothers often stay up late may lead to elevated prolactin, has been the secretion of estrogen, progesterone, thus affecting the blood supply of the placenta, the development of the fetus has a negative impact. 2. Fetal irritability after birth: due to the biological clock disorders during pregnancy, it will also have a certain impact on the sleep rhythm of the fetus after birth, resulting in poor sleep habits of newborns, easy to irritability, crying. Pregnant mothers who stay up late once in a while usually do not affect the fetus, do not have to be too nervous. It is recommended that pregnant mothers maintain healthy and regular sleep habits, which is not only beneficial to the growth and development of the fetus, but also very important to their own health. Pregnant women during pregnancy should pay attention to do a good job of prenatal checkups, actively listen to the advice of professional doctors to do a good job of comprehensive care and health care, pay attention to rest, at the same time should be relaxed, to avoid nervousness, anxiety, there is any discomfort should be timely to the hospital, by the doctor to clarify the diagnosis, and cooperate with the doctor to deal with the symptoms.