Fetal biometry, with the help of ultrasonography (USG) provides the most reliable and important information about fetal growth and well-being.
Frequently used parameters for fetal measurements by this method are the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL)..
Fetal biometric parameters are antenatal ultrasound measurements that are used to indirectly assess the growth and well being of the fetus..
Fetal biometry is the measurement of the fetus and various segments of the fetal anatomy.
Every part of the fetal anatomy may be imaged, but fetal head, abdomen, and femur measurements are the most commonly used, as well as the crown-rump length in early gestation..
In centimeters (cm), the median (average) ranges for fetal biometry measurements at around 20 weeks gestation are: Head circumference (HC): 17.5cm.
Abdominal circumference (AC): 14.9cm.
Biparietal diameter (BPD): 4.9cm..
The normal ratio of femur length to BPD (FL/BPD ratio) was found to be 79 +/- 8%.
Effective uses of the FL/BPD ratio include its use as a quality control check on femur length and BPD measurements and its use to diagnose short-limbed dwarfism, hydrocephalus, and microcephaly..
Biparietal diameter (BPD) is one of the basic biometric parameters used to assess fetal size.
BPD together with head circumference (HC), abdominal circumference (AC), and femur length (FL) are computed to produce an estimate of fetal weight..
Between 20 and 36 weeks of gestation, the HC/AC ratio normally drops almost linearly from 1.2 to 1.0.
The ratio is normal in the fetus with symmetric growth restriction and elevated in the infant with asymmetric growth restriction.
Another important use of ultrasound is estimating the amount of amniotic fluid..
Between 20 and 36 weeks of gestation, the HC/AC ratio normally drops almost linearly from 1.2 to 1.0.
The ratio is normal in the fetus with symmetric growth restriction and elevated in the infant with asymmetric growth restriction.
Another important use of ultrasound is estimating the amount of amniotic fluid..
Biometry, also commonly called biostatistics, is the application of mathematical and statistical models to biology.
Biometrics is a powerful tool for researchers, allowing generalizations and patterns to emerge from large data sets..
Head circumference/abdominal circumference (HC/AC) ratios of the fetus are accepted as a means of distinguishing different patterns of growth retardation with a high ratio implying malnutrition of the fetus..
Furthermore, no amount of laboratory testing can help to determine the base rate.
Threat modeling can assist in developing estimates of imposter base rates and is discussed in the next section.
Security considerations are critical to the design of any recognition system, and biometric systems are no exception.
The most frequently used biometric parameters for assessing fetal weight include:
Implicit in all biometric systems are estimated probabilities of the sameness and difference of source of samples and stored references, separately for presenters of different types, such as:
This leads to the explicit use of ratios of probabilities in some biometric recognition algorithms.
Probability distribution
