Amniotic fluid volumes in normal pregnancies

One hundred and eighty-seven amniotic fluid determinations were performed on 115 patients from 15 to 42 weeks' gestation by the para-aminohippurate method of Charles and Jacoby. Our results show a wide normal range which increases as pregnancy progresses. The significant variations in individual trends are shown. The mean volume rises from 239 ml. at 15 to 16 weeks to 669 ml. at 25 to 26 weeks and 984 ml. at 33 to 34 weeks; it then decreases slightly to 836 ml. at term and 544 ml. at 41 to 42 weeks. The role of amniotic fluid volume in relation to interpreting amniotic fluid constituents is discussed.