Serial measurements of serum human placental lactogen (hPL) and serial ultrasound examinations in the evaluation of fetal growth

Serial serum hPL measurements and serial ultrasound fetometry were compared in the evaluation of fetal growth by relating these two parameters to size at birth and to clinical factors known to influence size at birth. The dat a were from a prospective study of 1000 consecutive pregnant women consider ed to be at risk for fetal growth retardation with retrospective analysis. Serum hPL was measured by radioimmunoassay and fetal weight estimated by ul trasound every 3 weeks during the last trimester. hPL values were expressed as multiples of the median (MoM) and linear regression analysis of the hPL MoM values was carried out fur each pregnancy to find the slope of the lin e (hPL-slope); at least 3 serum hPL values were required. The estimated fet al weight and weight-fur-age at birth was expressed in Z-scores. The indivi dual intrauterine growth velocity was calculated by regression analysis and expressed as change in Z-score for 12 weeks. At least two ultrasound measu rements over an interval of at least 42 days were used to estimate the feta l growth velocity. In 588 women the file was complete. The main outcome mea sures were the individual mean hPL, hPL-slope, fetal growth velocity, birth weight deviation, smoking in pregnancy and diagnosis of preeclampsia. A si gnificant correlation was found between the hPL-slope and the intrauterine fetal growth velocity (r = 0.33), and between hPL-slope and birth weight de viation (r = 0.32). Mean hPL was correlated to birth weight deviation (r = 0.27), but only very weakly to intrauterine growth velocity (r = 0.08). hPL -slope and intrauterine growth velocity independently predicted birth weigh t deviation. Heavy smoking which was stopped before the third trimester was not associated with low intrauterine growth velocity, but with a low hPL-s lope. Preeclampsia was associated with a trend towards low and decreasing h PL and with an increasing intrauterine growth velocity and birth weight dev iation. In conclusion the rate of change of serial hPL measurements correla ted well to intrauterine fetal growth velocity in the third trimester as es timated by ultrasound and to the deviation in birth weight, but hPL seems t o have a separate physiological significance, since it did not pick up when smoking was stopped and growth velocity was normalised and it did not at a ll detect the increased growth associated with preeclampsia. (C) 2000 Elsev ier Science ireland Ltd. All rights reserved.