Although approximately half of the fetuses with abnormal AFVs have comorbidities, the deleterious effects of nonnormal AFVs are independent of the presence of comorbidities and occur in fetuses that are normal except for the aberrant AFV ( 59, 80, 100). These aberrations are associated with a wide variety of pregnancy complications and poor outcomes that lead to lifelong disease ( 36, 68, 75– 77, 86, 93). Presently, AFVs outside of the normal range occur in 5–10% of the ~4,000,000 births in the United States each year. Furthermore, AFV function curves and amnioinfusion function curves provide new insights into the relative efficacy of the stimulator and inhibitor of IMA.Īn amniotic fluid volume (AFV) in the normal range promotes the development of a healthy fetus. In the 2010s, it was demonstrated that a renally derived stimulator and a fetal membrane-derived inhibitor are present in amniotic fluid that regulate IMA rate and hence are the primary determinants of AFV. Over the next 25 years the concept of IMA evolved from being a passive process to being an active, unidirectional transport of amniotic fluid water and solutes by vesicles within the amnion. However, by the late 1980s, IMA was discovered to be a “missing link” in understanding the regulation of AFV. In the early 1980s, it was not known whether AFV was regulated. To put these concepts in perspective, this review 1) discusses the evolution of discoveries that form the current basis for understanding the regulation of AFV, 2) reviews the contribution of IMA to this regulation, and 3) interprets experimentally induced shifts in AFV function curves and amnioinfusion function curves in terms of the activity of the amniotic fluid stimulator and inhibitor of IMA. In turn, IMA rate is dependent on the concentrations of yet-to-be identified stimulator(s) and inhibitor(s) that are present in amniotic fluid. Recent advances in understanding the regulation of amniotic fluid volume (AFV) include that AFV is determined primarily by the rate of intramembranous absorption (IMA) of amniotic fluid across the amnion and into fetal blood.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |