Acid-base balance studies of amniotic fluid in rhesus monkeys

Acid-Base and Gas Tension Studies of the Amniotic Fluid in Human Gestation

“…Extremes of maturity in these studies prevent definitive conclusions and, despite the valuable data recently provided by Seeds and H ellegers [22], information has been sparse concerning gas tensions and acid-base balance of human amniotic fluid at intermediate gestational intervals between 26 and 36 weeks. Studies of gas tensions and acid-base balance in amniotic fluid from monkeys [23,24] also suggest a gradual acculation of hydrogen ions in the nearly neutral, slightly alkaline medium as gestation advances. Species variations appear to exist however, as the studies of Moss and Rettori [26] suggest a declining [H+] in sheep while the work of McCance and W iddowson [25] shows an identical mean pH of 7.20 in pigs at 67 and 90 days of gestation.…”

“…With excep tion of the study of Seeds and Hellegers [22], the few amniotic fluids from early human gestation were collected at time of therapeutic abortion and, with a single exception [11], P C 02 measurements in all of these studies have been calculated from pH determinations using either the Astrup technique [30] or H enderson-H asselbalch equa tion [31]. In contrast, studies in sheep [26,27], monkeys [23,24], pigs [25], and rabbits [28] have spanned the later half of gestation and direct pH and P C 0 2 measurements have suggested a linear relation ship of both parameters with gestational age. It has also been sug gested by several of these authors that acid-base composition and oxygen tension of amniotic fluid may reflect fetal compromise in both human and other mammalian pregnancies [7,9,12,16,18,20,24,29].…”

“…Prompted by the early studies of Sjostedt and his associates [6][7][8][9], several investigators have examined the acid-base status and oxygen tension of amniotic fluid in both human [10][11][12][13][14][15][16][17][18][19][20][21][22] and other mammalian gestations [23][24][25][26][27][28][29], In the human, most of these studies were performed immediately prior to the term delivery of a mature fetus. With excep tion of the study of Seeds and Hellegers [22], the few amniotic fluids from early human gestation were collected at time of therapeutic abortion and, with a single exception [11], P C 02 measurements in all of these studies have been calculated from pH determinations using either the Astrup technique [30] or H enderson-H asselbalch equa tion [31].…”