The intrauterine ponderal index in relation to birth weight discordance in twin gestations.
OBJECTIVE
To establish the relationship between the fetal ponderal index and birth weight discordance in twins.


METHODS
The fetal ponderal index (estimated fetal weight divided by femur length3) was calculated in 86 pairs of twins delivered within 2 weeks of the last sonography and analyzed in relation to birth weight discordance.


RESULTS
A weak but significant correlation between fetal ponderal index and birth weight (r = 0.26, P < 0.0007) but no correlation with gestational age (r = 0.035, P = 0.65) were found. Members of concordant pairs (< 15% birth weight difference) had a significantly higher fetal ponderal index compared with members of mildly (15-25%) discordant pairs (P < 0.02), but not as compared with members of severely discordant (> 25%) pairs.


CONCLUSIONS
The characteristics of the fetal ponderal index in twins are similar to those in singletons. Fetal size seems to be diminished in severe but not in mild discordants. However, in its present form, the fetal ponderal index is a poor predictor of discordant growth and therefore should be employed cautiously in twin gestations.
Department of Obstetrics and Gynecology, Kaplan Hospital, Rehovot, Israel.
I
I
Blickstein
M
M
Manor
R
R
Levi
R
R
Goldchmit
A
A
Weissman
D001724:Birth Weight; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000502:physiology*; D014427:Twins; D016216:Ultrasonography, Prenatal