title: Gastric emptying cycles in the human fetus.
abstract: OBJECTIVE
  Fetal swallowing contributes greatly to amniotic fluid homeostasis and fetal somatic development. Despite the absorption and recirculation of significant volumes of amniotic fluid, little is known about the rates of fetal gastric emptying or gastrointestinal absorption. We sought to determine the patterns of human fetal gastric emptying cycles across gestation.
  
  
  METHODS
  The gastric emptying cycle of 80 normal human fetuses at 12 to 39 weeks of gestation was studied. Real-time ultrasound examination of the fetal stomach (defined as the largest gastric area inclusive of the pylorus) was recorded continuously for a minimum of 1 hour (60-112 minutes). Images were replayed with measurements of gastric size every minute. The gastric area ratio was defined as the ratio of the fetal gastric area divided by the area of the fetal abdominal transverse section. The changes in gastric area ratio of all subjects were analyzed with the discrete Fourier transform method. The calculable maximum cycle was 60 or 112 minutes, and the minimum cycle was 2 minutes. The highest and second highest peaks of all power spectrum were recorded, and each cycle was converted from frequency of each peak.
  
  
  RESULTS
  The gastric emptying cycles of the highest peak before 24 weeks of gestation were scattered between 30 and 100 minutes with low power. At 32 to 35 weeks of gestation, cycles were focused at approximately 40 minutes with increased power. At term, the cycles increased to >80 minutes. The gastric emptying cycles of the second highest peak were constant at 20 minutes, with stronger power after 24 weeks of gestation.
  
  
  CONCLUSIONS
  Fetal gastric emptying cycles normalize during the early third trimester. The near-term evidence of delayed emptying may contribute to newborn infant feeding satiation.
authors.affiliation: Department of Reproductive, Pediatric, and Infection Science, Division of Medicine for Maternal and Child Health, Yamaguchi University School of Medicine, Japan. mikeross@ucla.edu
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Sase
authors.forename: Ichiro
authors.initials: I
authors.lastname: Miwa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sumie
authors.forename: Masahiko
authors.initials: M
authors.lastname: Nakata
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sugino
authors.forename: Kouichi
authors.initials: K
authors.lastname: Okada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Osa
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Miike
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ross
mesh_terms: D000328:Adult; D003679:Deglutition / Q000502:physiology; D005260:Female; D005333:Fetus / Q000502:physiology*; D005746:Gastric Emptying / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D010528:Peristalsis / Q000502:physiology*; D011247:Pregnancy; D013270:Stomach / Q000196:embryology*