The individual fetal weight/estimated placental weight ratios in monochorionic twins with selective intrauterine growth restriction.
OBJECTIVE
To evaluate the individual fetal weight/estimated placental weight ratios (F/P ratio) of the two fetuses in monochorionic (MC) twins with selective intrauterine growth restriction (IUGR).


METHODS
MC twin with selective IUGR was defined as an estimated fetal weight below the 10th percentile in one twin of MC pregnancy. The estimated individual placental weight was obtained by cutting the placenta along the vascular equator into two territories. A total of 15 MC twins with selective IUGR and 18 MC twins without selective IUGR were included in this study.


RESULTS
The individual F/P ratio in the IUGR twin is significantly higher than that in the appropriate for gestational age (AGA) one in MC twin with selective IUGR (6.4 vs 4.0 respectively, p < 0.001). In MC twin without IUGR, the F/P ratios are not significantly different between the two fetuses (5.4 vs 5.1, respectively).


CONCLUSIONS
The high F/P ratio in the IUGR twin in MC with selective IUGR may be due to the placental reserve phenomenon, so that a smaller placental territory may suffice to perfuse the IUGR twin. In other words, in MC twin gestations with an IUGR twin, the fetal weights are not proportional to the placental masses.
Chang
Yao-Lung
YL
Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, 5, Fu-Shin Street, Kweishan, Taoyuan 333, Taiwan, ROC. j12054@cgmh.org.tw
Chang
Shuenn-Dyh
SD
Chao
An-Shine
AS
Hsieh
Peter C C
PC
Wang
Chao-Nin
CN
Tseng
Ling-Hong
LH
D002823:Chorion; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis*; D020567:Fetal Weight; D005865:Gestational Age; D006801:Humans; D010920:Placenta / Q000503:physiopathology*; D011247:Pregnancy; D011446:Prospective Studies; D014430:Twins, Monozygotic