Remember that ultrasound is safe for the fetus and has no limitations in pregnancy. In the case of favorable course of pregnancy this kind of prenatal diagnosis you will be assigned three times.
Note that different timeOh pregnancy doctor available amount of information about the fetus, and the period of pregnancy is set according to strictly defined criteria. Therefore, a so-called screening and defined periodand that ultrasonographic examination is more accurate, for this important time period information. For example, the gestational periode 2-3 weeks in the uterine cavity is visualized only the ovum is, roughly speaking, a doctor can give the conclusion she is pregnant or not. With 4 weeks of gestation experienced ultrasound doctor can see the body of the embryo (the average size of the ovum will be in this period of 3-4 mm). At 4-5 weeks, you record the heartbeat of the baby. Separate movements of the baby are visualized with 7 weeks of fetal life.
Head as a separate anatomical education is defined from 8 weeks, and of course with 9 weeks of pregnancy. During this period, the doctor evaluates the size of the middle inner diameter of the ovum (SVD) and kopcik-parietal size of the embryo (CTE) and compares the received data with tabular or program ultrasound scanners, and determines a period of pregnancy with an accuracy of ± 6 days. At the end of the first trimester of development (11-12 weeks) you can scan a particular structure of the brain of the unborn child. It was at this time the ultrasound said period of pregnancy, is determined by the number of fetuses, measure the nuchal translucency thickness and nasal bone for exclusion of chromosomal defects.
Be aware that in the future your little one on the ultrasound display apparatus will be more and more like a real person. Each time during the study doctor will carry out the measurement of key indicators of biophysical development of the fetus, namely biparietal (between the parietal tuber) and labanotation sizes of head, chest circumference, abdominal circumference, length of the nasal bone, length of femur. Developed specific tables and embedded programs for ultrasound devices, which can determine the period of pregnancy with an accuracy of ± 1 week.