Appropriate dating age formula
A Cochrane review concluded "There is insufficient evidence to determine whether SFH measurement is effective in detecting IUGR. We cannot therefore recommended any change of current practice. Many regression equations are available using various combinations of parameters to estimate the gestational age. Some clinicians use the unweighted mean of the 4 most commonly used biometric parameters ( biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) ) to establish a gestational age  Ultrasound Estimate of Fetal Weight In practice the most common equations for calculating the estimated fetal weight (EFW) are reported to be the Shepard and Hadlock formulas [5,8,9]: Shepard: Log 10 (weight) = -1.7492 0.166*BPD 0.046*AC - 2.646*(AC*BPD)/1,000 Hadlock 1: Log 10 (weight) = 1.304 0.05281*Ac 0.1938*FL -0.004*AC*FL Hadlock 2: Log 10 (weight) = 1.335-0.0034*AC*FL 0.0316*BPD 0.0457*AC 0.1623*FL Hadlock 3: Log 10 (weight) =1.326-0.00326 *AC*FL 0.0107*HC 0.0438*AC 0.158*FL Hadlock 4: Log10 (weight) =1.3596 -0.00386* AC * FL 0.0064*HC 0.00061*BPD*AC 0.0424*AC 0.174*FL Regardless of the formula used the accuracy of the sonographic estimate of the EFW is affected by supoptimal imaging and biological variation . al., Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters.
Measurement of the symphysis-fundal height (SFH) is a common screening method used to estimate the gestational age and fetal growth after 24 weeks gestation. TABLE 2 70% of infants born below the 10th percentile are not at risk for adverse outcomes . The difference in size between babies is most often due to constitutional causes such as the size of the baby's parents, ethnic background , or the sex of the baby . Very small and very large babies have higher mortality and morbidity rates than infants of normal size . al., Evaluating the thresholds of abnormal second trimester multiple marker screening tests associated with intra-uterine growth restriction. Because early detection of growth abnormalities may help to prevent fetal demise and manage perinatal complications more appropriately , monitoring of fetal growth is an important part of antepartum care. The suggested results are not a substitute for clinical judgment.
The distance from the top of the pubic bone (symphysis pubis) to the top of the pregnant uterus (fundus) is measured in centimeters (cm).