Ultrasound Measurement of Placental Thickness in Normal Singleton Pregnancy

Abstract

Objective To establish a normative data of placental thickness in normal fetus across gestation.

Methods A prospective longitudinal study of 134 pregnant women recruited from the antenatal clinic was performed. They were randomized into 4 groups (A, B, C and D). Each group had first transabdominal ultrasound examination done at 18, 19, 20 and 21 weeks, respectively. The follow-up scan was then performed at 4-week interval until term. The estimation of gestational age has confined to the used of BPD, HC, AC and FL. Placental thickness was obtained by scanning perpendicularly through the thickest part of placenta. All newborns were proved to be normal at birth. The data was analyzed for mean, standard deviation, the 5th, 50th and 95th percentile. The best fit mathematical model was derived using SPSS computer program.

Results The total number of measurements were 683. The number of measure ments at each gestational week ranged from 2 to 44. The best regression model between gestational age and placental thickness obtaining from random sampling of single measurement in each patient was observed to be linear : Placental thickness (mm) = 14.5927 + 0.719 Gestational age (weeks), r = 0.483.

Conclusion The nomogram for placental thickness of our population was established. This may be a useful aid in the prenatal diagnosis of fetal growth restriction and hydrops fetalis.