Fetal hiccups indicate that the diaphragm or stomach muscles are not well developed, while the indicator of lung maturity is mainly the ratio of lecithin to sphingomyelin, and the two are not very related. Fetal hiccups are regular contractions of the diaphragm, usually caused by the fetus swallowing amniotic fluid, usually appearing after 28 weeks of gestation, about 2 to 3 seconds once, once lasts about 5 minutes. The maturation of the fetal lungs, usually after 36 weeks of pregnancy, the ratio of lecithin to sphingomyelin in amniotic fluid is greater than 2 suggesting that the fetal lungs are mature, and the ratio is less than 1 generally suggests that the fetal lungs are immature, these two substances are mainly secreted by the alveolar cells, and have nothing to do with the fetal hiccups. If the fetus hiccups, usually a normal phenomenon, do not have to worry too much, if there are other symptoms of discomfort should be timely consultation and treatment.