Correlation between umbilical resistance index and fetal growth: Pilot study.
OBJECTIVE
To investigate normal pregnancies to determine whether there is a relationship between umbilical resistance and fetal growth.


METHODS
This prospective study was conducted in three academic departments. Third trimester routine prenatal ultrasonography was used to estimate fetal weight and measure umbilical resistance index (RI). After delivery the birthweight was noted, along with the time interval between the ultrasound and the delivery, and then the weekly weight gain was calculated. These data were then used to determine the relationship between fetal growth and umbilical artery RI.


RESULTS
Mean patient age was 32 ± 4.8 years; mean RI was 0.62 ± 0.07, and mean weight gain was 186.4 ± 63.9 g/week. Mean percentage weight gain relative to the estimated weight on third trimester ultrasound was 8.86 ± 3.8% per week. There was an inverse linear relationship between umbilical artery RI and fetal growth: percentage of weight gained per week relative to the estimated weight during third trimester ultrasound (%/week) = [31.3 - (36.1 × RI)] × 100.


CONCLUSIONS
In normal pregnancies there seems to be a linear relationship between umbilical RI measured at 31-34 weeks of gestation and average fetal growth in the third trimester. The greater the resistance index, the lower the weight gain.
C Department of Obstetrics and Gynecology, Tunis Maternity Center, Tunis El Manar University, Tunisia.
Mehdi
M
Kehila
C Department of Obstetrics and Gynecology, Tunis Maternity Center, Tunis El Manar University, Tunisia.
Omar
O
Touhami
C Department of Obstetrics and Gynecology, Tunis Maternity Center, Tunis El Manar University, Tunisia.
Rim Ben
RB
Hmid
C Department of Obstetrics and Gynecology, Tunis Maternity Center, Tunis El Manar University, Tunisia.
Hassine Saber
HS
Abouda
Department of Obstetrics and Gynecology, Farhat Hached Teaching Hospital, Sousse, Tunisia.
Khlifi
K
Abdeljelil
Department of Obstetrics and Gynecology, Bizerte Teaching Hospital, Tunis El Manar University, Tunisia.
Amira
A
Ayachi
Department of Obstetrics and Gynecology, Bizerte Teaching Hospital, Tunis El Manar University, Tunisia.
Mechaal
M
Mourali
Department of Obstetrics and Gynecology, Farhat Hached Teaching Hospital, Sousse, Tunisia.
Hédi
H
Khairi
C Department of Obstetrics and Gynecology, Tunis Maternity Center, Tunis El Manar University, Tunisia.
Mohamed Badis
MB
Chanoufi
D000328:Adult; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D010865:Pilot Projects; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging*
fetal growth; resistance index; ultrasound; umbilical Doppler