THE INDIVIDUALIZED BIRTH-WEIGHT RATIO - A NEW METHOD OF IDENTIFYING INTRAUTERINE GROWTH-RETARDATION

Objective To assess the effectiveness of the newly developed individua lised birthweight ratio in identifying growth retarded infants. Design Prospective observational study. Setting Obstetric unit, City Hospita l Nottingham. Subjects Two thousand eight hundred and thirty-five wome n delivered between December 1991 and July 1992 and the infants of 616 of these selected by virtue of their birthweight for gestation and in dividualised birthweight ratio centile positions. Main outcome measure s Skinfold thickness and ponderal index measurements, occurrence of ab normal fetal heart rate patterns, operative delivery due to fetal dist ress and the need for neonatal resuscitation. Results Using an individ ualised birthweight ratio less than the 10th centile as a cut-off resu lts in 25% of those less than the 10th centile of birthweight for gest ation being reclassified as normally grown. A slightly larger group ar e reclassified as small; significantly more of these infants have abno rmal ponderal indices and skinfold thicknesses, suffer abnormal fetal heart rate patterns, operative delivery for fetal distress and need ne onatal resuscitation than do those who are reclassified as normally gr own. Conclusion The individualised birthweight ratio combines the simp licity of birthweight measurement with the accuracy of clinical measur ements in the identification of the growth retarded baby.