Umbilical artery Doppler studies in small for gestational age babies reflect disease severity

Objectives To determine: 1. whether abnormal umbilical artery Doppler studi es were independently associated with newborn morbidity; and 2. whether sma ll for gestational age babies with normal umbilical artery Doppler studies had small mothers and a low rate of newborn malnutrition and morbidity. Design Prospective observational study. Setting National Women's Hospital, a tertiary referral centre, Auckland, Ne w Zealand. Population One hundred eighty-six women and their small for gestational age babies (birthweight < 10th%) who had been participants in one of two rando mised controlled trials of small for gestational age pregnancies between 19 93 and 1997. Methods Newborn morbidity and morphometry were compared between small for g estational age babies with normal and abnormal umbilical artery Doppler stu dies (resistance index > 95th%). Maternal demographic characteristics and m orbidity were also compared. Results Compared with small for gestational age babies with normal umbilica l artery Doppler studies (n = 109), small for gestational age babies with a bnormal umbilical artery Doppler studies (n = 77) were diagnosed earlier in pregnancy as being small for gestational age (30.3 vs 32.9 weeks, P < 0.00 1), were smaller in all body proportions at birth (median Z score birthweig ht -1.82 vs -1.70, P = 0.004, Z score length -1.86 vs -1.36, P < 0.0001, Z score head circumference -1.31 vs -0.89, P < 0.0001) and were more likely t o experience newborn morbidity. When birthweight and gestation were entered into a logistic regression model, an abnormal umbilical artery Doppler stu dy was not an independent predictor of prolonged newborn nursery admission or hypoglycaemia. Of small for gestational age babies with normal umbilical artery Doppler studies, 53 (49%) had low ponderal indices, 26/98 (26%) wer e hypoglycaemic and 38 (35%) required admission to the newborn nursery. The re was no difference in maternal height, weight and ethnicity between the a bnormal and normal umbilical artery Doppler groups. Conclusions Abnormal umbilical artery Doppler studies reflect earlier onset and more severe growth restriction and are not independently associated wi th newborn morbidity. Small for gestational age babies with normal Doppler studies have a high rate of newborn nursery admission and malnutrition at b irth and are not all just normal small babies.