[Digestive physiopathology of the fetus]

The evolution en enzymatic activity in the amniotic fluid follows the various stages of development of the gastrointestinal tract during pregnancy. Before 12 weeks of amenorrhea, no enzymatic activity can be detected, as this period corresponds to the persistence of the pharyngeal and anal membranes. At 13-14 weeks, a very high level of enzymatic activity is suddenly observed in the amniotic fluid, reaching its peak at 16-18 weeks. This phase corresponds to the opening of the pharyngeal membrane, the appearance of swallowing and the opening of the anal membrane. After 18 weeks, the digestive enzyme level progressively decreases until 22-24 weeks, after which date no gastrointestinal enzymatic activity can be evidenced in normal fetuses (probably because of functional anorectal obstruction). We have determined the enzymatic anomalies related to some gastrointestinal deformations (duodenal atresia, cystic fibrosis, atresia of the bile ducts, anorectal atresia).