Fetal Femur Length in Assessment of Gestational Age in Third Trimester in Women of Northern India (Lucknow, UP) and a Comparative Study with Western and Other Asian Countries.

ABSTRACT

Introduction: Gestational age (GA) estimation is the most important part of obstetric practice and ultrasonic study plays an important role in its accurate estimation. Fetal femur length (FL) is one of the parameters used for estimation of GA along with biparietal diameter, head circumference and abdominal circumference (AC). Objective: This study is an attempt to correlate fetal FL with GA and to ascertain if fetal FL can be used as a parameter to calculate the GA in third trimester of pregnancy in Indian women with moderate accuracy. Findings have been compared with the work of sonologists from other countries. Material and methods: Pregnant women in the third trimester of pregnancy with single live fetus and having no other complication either in mother or fetus, were selected for the study, fetal FL along with other parameters was measured. The results were analyzed for accuracy in estimation of GA by FL and were compared with findings of other workers. Result: GA estimated from FL in 512 cases between 27-39 weeks of gestation showed that quadratic model has a good fit to the data and r2 = 0.785 with standard error + 8 days. There was a significant difference with Iranians and Bangladesh women in comparison to our findings. The paired t-test between Indian and Bangladesh, women was significant, (p < 0.001). The findings in our study were similar to the results of Western fetal FLs. Conclusion: The data can be useful in estimation of GA by FL. Our error was + 8 days. A bigger study involving same number of cases in each week of gestation in third trimester is necessary to get an accurate formula for assessment of GA by FL.