Construction of fetal charts for biparietal diameter, fetal abdominal circumference and femur length in Bangladeshi population.

Infants born for small for date (SFD) fetuses have an increased risk of perinatal mortality and morbidity. Different methods have been applied to identify these fetuses including history, clinical examination and ultrasonography. Ultrasonography has a better predictive value and majority of such fetuses can be identified. Measurements of the fetal biparietal diameter (BPD), abdominal circumference (AC) and femur length (FL) charts are widely used in dating pregnancies and follow-up of pregnant women in assessing fetal growth, identification of small for date (SFD) and growth retarded fetuses. This prospective study was performed to construct fetal chart for BPD, AC and FL at different gestational weeks from the Bangladeshi pregnant women. Seven hundred and ten women had ultrasonic measurements of fetal BPD, AC and FL between 12 to 42 weeks of pregnancy. Centiles, mean and the standard deviation (SD) were calculated for BPD, AC and FL. Mean maternal age was 24.73 +/- 4.48 (Mean +/- SD) and 310 (43.7%) were primigravidae. There was a gradual increase of the BPD (outer-inner), AC and FL measurements of 5th, 10th, 50th and 90th Centiles upto 38th weeks of gestation with a gradual increase of SD showing increasing dispersion of data. In cases of BPD and AC, After 38th weeks of gestation the Centiles showed a slower growth rate towards 42 weeks of pregnancy. This slower growth rate from 38 weeks of pregnancy was not noted in case of femur length. Fetal charts with the raw data for each measurement with superimposed fitted lines derived from polynomial (quadratic) regression were constructed. Quadratic model showed good fit to the data during construction of fetal charts. The new fetal measurement charts of BPD, AC and FL are unique for the Bangladeshi population and have not been found similar in the later weeks of pregnancy to those published for other Caucasian populations. These charts will help the clinicians and sonographers in dating pregnancy, identifying SFD and growth retarded fetuses.