Lactate to creatinine ratio in amniotic fluid: a pilot study.

Measurement of amniotic fluid (AF) lactate concentration in complicated pregnancies may provide information on the extent of fetal acidemia. However, normalisation for AF volume may be necessary by calculating the lactate:creatinine (L:C) ratio. We measured these AF parameters and compared them to arterial cord blood lactate in 28 term and 10 preterm pregnancies. Cord blood lactate was not correlated to AF lactate, but was correlated to the L:C ratio in the complete study population (R = 0.54, p = 0.001) and the subgroups. Correlation was strongest in a preterm intrauterine growth restricted subgroup (n = 7, R = 0.83, p = 0.02). The L:C ratio is more accurate in estimating fetal lacticaemia than AF lactate.