Gestational age estimation using fetal foot length and transcerebellar diameter - A prospective study.

The present study will be undertakenin the Dept. of Obstetrics & Gynaecology at Pondicherry Institute of MedicalSciences, Pondicherry. Pregnant women satisfying the inclusioncriteria, after obtaining a written informed consent, will be enrolled into thestudy between 8 + 0 weeks and 12 + 6 weeks. Fetuses will be scanned in the first trimester for the estimation of gestational age by measurement of crown-rump length (CRL), and then subsequently at monthly intervals for fetal biometry from 18 weeks onwards till 40 weeks. All scans will be performed by theprimary investigator or co-investigator. The following ultrasound measurements willbe obtained at all visits: Biparietal diameter (BPD), Head circumference (HC), Abdominalcircumference (AC), Femur length (FL), Transcerebellar diameter (TCD) and Fetal Foot length (FFL). Patients will be followed up until delivery and birthweight will be noted.   Data will be entered in Microsoft Excel spread sheet and analysed using SPSS software. Linear regression models for estimation of gestational age will bederived from the biometric indices, fetal foot length and transcerebellardiameter. Correlation tests will be applied to measure the correlation between FFL, TCD and gestational age;and to compare them with the other biometric parameters.