title: Doppler evaluation of umbilical venous and arterial blood flow in the second and third trimesters of normal pregnancy.
abstract: Duplex Doppler ultrasound was used to measure umbilical venous blood flow in 209 normal pregnant women between 20-40 weeks' gestation. The relationship between umbilical venous blood flow and gestational age increased with gestational age, and is described by the equation y = -187.02 + 12.7x. The relationship between flow per kilogram fetal weight and gestational age (y = 198.629 - 2.24x) yielded values of 153 mL/minute/kg at 20 weeks, 131 mL/minute/kg at 30 weeks, and 108 mL/minute/kg at 40 weeks. Doppler ultrasound was also used to evaluate umbilical arterial waveforms (systolic/diastolic ratio) in 171 normal pregnant women between 20-40 weeks. The relationship between systolic/diastolic ratios and gestational age (y = 6.46 - 0.12x) decreased with advancing gestational age, yielding mean systolic/diastolic ratios (+/- 2 SD) of 4.1 (5.6, 2.6) at 20 weeks, 3.6 (5.1, 2.1) at 24 weeks, 3.1 (4.6, 1.6) at 28 weeks, 2.6 (4.1, 1.1) at 32 weeks, 2.1 (3.6, 0.6) at 36 weeks, and 1.7 (3.1, 0.1) at 40 weeks.
mesh_terms: D001783:Blood Flow Velocity; D005260:Female; D005865:Gestational Age; D006801:Humans; D009200:Myocardial Contraction; D011247:Pregnancy / Q000502:physiology*; D012016:Reference Values; D012212:Rheology; D014469:Umbilical Arteries / Q000502:physiology*; D014471:Umbilical Veins / Q000502:physiology*