Prediction of intrauterine growth restriction with customized estimated fetal weight centiles

ABSTRACT

1-To determine the value of third trimester customized estimated fetal weight centile ranking in the prediction of' infants born with anthropometric features of intrauterine growth restriction [IUGR]. 2-To compare the performance of customized centiles with fetal growth velocity in the prediction of IUGR. Prospective observational study. Two hundred women with low risk pregnancy were enrolled in this study. Third trimester estimated fetal weight customized centiles were obtained after adjustment for gestational age at the time of ultrasound measurements biparietal diameter [BPD], femur length [FL], fetal abdominal circumference [AC], H/A ratio, F/A ratio, and estimated fetal weight [EFW]. Fetal growth velocity was calculated using the increment in the fetal abdominal area over a mean 28-day interval. [Fetal abdominal area growth velocity was expressed as a standard deviation [Z score]]. Receiver Operator Characteristics curves employed to determine an optimal cut off point for velocity to predict IUGR fetus. After delivery all neonates were subjected to the following anthropometric measurements fetal body weight, length, head circumference, mid-arm circumference, and triceps and subscapular skin fold thickness. Gestational age was assessed using Ballard scoring system. Ponderal index [PI] was calculated and velocity standard deviation [Velocity Z score] was determined for BPD, AC and FL. The neonatal anthropometric measures were used to define IUGR subscapular or triceps skin-fold thickness<10th centile, PI<25th centile, mid-ami circumference to occipito-frontal circumference<-1SD. The ability of estimated fetal weight customized centiles<5th centile and cloth centile to identi and growth restriction was determined by calculating likelihood ratios. Sixteen [8%] and eight [4%] infants had adjusted birth weights below the 10th and 5th centiles, respectively. 30 infants had one or both skinfold thickness measurements below the 10th centile, 36 had a ponderal index below the 25th centile and 16 had mid-arm circumference to occipito-frontal circumference<-1SD. The mean and range of estimated fetal weight [EFW] customized centiles was 39.3 [0.6-99.8]; the mean and range of interval between gestational age at calculation of the EFW customized centiles and delivery was 12 days [0-60]. The customized EFW centile of 5 or less had likelihood ratios [95% CI] of 4.9 [2.7-6.3], 6.8 [4.5-10.6] and 62 [17-14] for skinfold thickness<10th centile, ponderal index<25th centile and mid-arm circumference to occipito-frontal circumference<-1 SD, respectively. An EFW customized centile of 10 or less had likelihood ratios of 405 [2.6-8.6], 4.1 [2.5-7.2] and 7.1[3.5-24] for skinfold thickness<10th centile, ponderal index<25th centile and mid-arm circumference to occipitofrontal circumference<-1 SD, respectively. In the prediction of a ponderal index<25th centile, the fetal abdominal area velocity likelihood ratio for a positive test is higher than the likelihood ratio for the 10th EFW centile [r=0.04] but is not significantly higherforthe other outcomes. Serial ultrasound fetal abdominal circumference measurement is a good indicator for IUGR. Skin fold measurement and neonatal ponderal index are better indicators for IUGR than do birth weight alone. So for better detection of IUGR cases, serial ultrasound measurement during pregnancy even in low risk population is needed to pick up probably growth retarded infants, so possible fetal and/or neonatal complications could be dealt with