Hiccups in the fetus are neither hungry nor full, they are a way of exercising the breathing function of the lungs. Hiccups are a normal phenomenon in fetuses. Since the lungs of fetuses are not fully developed, they need to practice lung breathing by swallowing amniotic fluid in the womb, so as to prepare for breathing after birth. Swallowing of amniotic fluid usually occurs at around 28 weeks of gestation, causing the alveoli to expand in the amniotic fluid and producing hiccups. The thick muscular membrane between the chest and abdominal cavities, called the diaphragm, undergoes spasmodic and paroxysmal contractions, resulting in hiccups. Fetal babies can hiccups can cause the lungs to open and close, which can be jittery, which in turn can promote the maturation of the lungs. In addition, if the hiccups of the fetus baby appear abnormal need to seek prompt medical treatment.