Individualized norms of optimal fetal growth: fetal growth potential.
OBJECTIVE
To demonstrate that individualized optimal fetal growth norms, accounting for physiologic and pathologic determinants of fetal growth, better identify normal and abnormal outcomes of pregnancy than existing methods.


METHODS
In a prospective cohort of 38,033 singleton pregnancies, we identified 9,818 women with a completely normal outcome of pregnancy and characterized the physiologic factors affecting birth weight using multivariable regression. We used those physiologic factors to individually predict optimal growth trajectory and its variation, growth potential, for each fetus in the entire cohort. By comparing actual birth weight with growth potential, population, ultrasound, and customized norms, we calculated for each fetus achieved percentiles, by each norm. We then compared proportions of pregnancies classified as normally grown, between 10th and 90th percentile, or aberrantly grown, outside this interval, by growth potential and traditional norms, in 14,229 complicated pregnancies, 1,518 pregnancies with diabetes or hypertensive disorders, and 1,347 pregnancies with neonatal complications.


RESULTS
Nineteen physiologic factors, associated with maternal characteristics and early placental function, were identified. Growth potential norms correctly classified significantly more pregnancies than population, ultrasound, or customized norms in complicated pregnancies (26.4% compared with 18.3%, 18.7%, 22.8%, respectively, all P<.05), pregnancies with diabetes or hypertensive disorders (37.3% compared with 23.0%, 28.0%, 34.0%, respectively, all P<.05) and neonatal complications (33.3% compared with 19.7%, 24.9%, 29.8%, respectively, all P<.05).


CONCLUSIONS
Growth potential norms based on the physiologic determinants of birth weight are a better discriminator of aberrations of fetal growth than traditional norms.


METHODS
II.
Bukowski
Radek
R
Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555, USA. rkbukows@utmb.edu
Uchida
Tatsuo
T
Smith
Gordon C S
GC
Malone
Fergal D
FD
Ball
Robert H
RH
Nyberg
David A
DA
Comstock
Christine H
CH
Hankins
Gary D V
GD
Berkowitz
Richard L
RL
Gross
Susan J
SJ
Dugoff
Lorraine
L
Craigo
Sabrina D
SD
Timor
Ilan E
IE
Carr
Stephen R
SR
Wolfe
Honor M
HM
D'Alton
Mary E
ME
D000328:Adult; D001724:Birth Weight; D006063:Chorionic Gonadotropin / Q000097:blood; D004964:Estriol / Q000097:blood; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000503:physiopathology; D007265:Inhibins / Q000097:blood; D010925:Placental Function Tests; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000503:physiopathology; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011446:Prospective Studies; D012016:Reference Values; D016216:Ultrasonography, Prenatal
D006063:Chorionic Gonadotropin; C422362:inhibin A; D007265:Inhibins; D011266:Pregnancy-Associated Plasma Protein-A; D004964:Estriol