Sonographic assessment of gestational age in Nepalese population

Abstract

Introduction: Knowledge of gestational age is important for the management of pregnancy.Ultrasonography is a safe and reliable method for accessing gestational age. However, since built and stature are differ amongst various ethnic groups, nomograms based on western population may not be relevant to our community. This study is carried out to determine gestational age of Nepalese women, to compare with previously published charts and to standardize the gestational age charts for Nepalese population.

Methods: Nepalese women with a history of amenorrhea coming for ultrasound scan in the Department of Radiology and Imaging, TUTH were included in this prospective study. About 630 patients fulfilling the criteria were screened for BPD, HC, AC and FL during one year from 15thAugust 2004 to 14th June 2005. A gestational chart was made from the data and it was compared with the previously published charts.

Results: All fetal biometric parameters showed an increase with gestation. When compared with that of Hadlock’s nomogram, our values were similar at 20-21 weeks. After 21 weeks, our estimated values decreased gradually with a difference of 3-5mm in BPD, 3-24mm in HC, 1-21mm in AC and 1-4 mm in FL.
Conclusions: There was earlier flattening of growth starting from 22 weeks. The nomogram of Hadlock significantly overestimated gestational age in the later part of third trimester from 34 weeks onwards. This supported the argument that there is a need to have our own nomogram.