What is biparietal size?
The biparietal size of the baby's head (or BDP of the fetus), the table of which any doctor specializing in ultrasound diagnostics should know, is one of the most accurate indices of gestational age. It is determined by the results of ultrasound. The maximum informative value of this indicator is observed at 12-28 weeks of pregnancy.
BDP - the distance between the inner and outer contours of both parietal bones, that is, the line that connects the outer contours of the parietal bones. It must pass over the thalamus. This is the so-called "width" of the head, which is measured from the temple to the temple along the minor axis.
For any gestation period, there is a certain value of the index under consideration in the norm. As pregnancy develops, this indicator also increases, but by the end of gestation its growth rate is significantly reduced. Deviation from the accepted measurement rules often leads to a distortion of the results obtained, due to which the period of pregnancy is incorrectly determined.
Table of biparietal size of fetal head
Below is the BDP table. It reflects the indices of the index from 11 to 40 weeks of gestation, since it is at this time that ultrasound specialists measure it at each study.
This index should not be estimated autonomously, but together with the frontal-occipital size. They are measured in one plane and vary in direct proportion to the period of intrauterine development. For maximum accuracy, the circumference of the abdomen and the length of the thigh are also measured.
Measurement of BDP allows to identify certain disorders in the development of the baby, namely: intrauterine growth retardation, hydrocephalus, excessive weight of the baby (if this is exceeded) or microcephaly (if they are deficient). In this case, the results of other measurements are necessarily taken into account.