Date of the first day of menstruation indicates the beginning of a cycle of oocyte maturation, which subsequently fertilized and lead to pregnancy. It is believed that pregnancy occurs 2 weeks after the beginning of the menstrual cycle, because most ovulation occurs on day 14 of the cycle, and it is in this day a woman can get pregnant. If the woman does not remember when was my period, the period is determined by the other leading factors. Sometimes, the pregnancy, but there is about month, in this case, the date when it was spotting, does not affect the period of fetal development.
At statement on the account of pregnant obstetrician necessarily carries out a pelvic exam. The vulva of a pregnant acquire cyanonet (bluish tint) at 6-8 weeks of pregnancy.
When pregnancy is characterized by persistent areas of redness on the cervix (Chadwick symptom). Gynecologist palpates uterus, determining its size. At each period of fetal life the genital organ has a certain size. For example, in 7 weeks of pregnancy the uterus approximately with the average chicken egg, for 10 weeks it has a size of 110 by 80 mm, etc.
Fetal ultrasound gives the most accurate information about the pregnancy. Doctor with ultrasound in the first trimester of pregnancy measures the display apparatus of kopchik-parietal size of a fetus, biparietal size of the embryo and diameter of yolk sack. With 5-6 weeks of pregnancy experienced uzist-gynecologist will distinguish the length of the body of the embryo, which is 3-6 mm, then the fetus grows and the size increases. With 8 weeks of fetal development is determined by biparietal head size of the fetus at this period it is approximately 6 mm. Diameter of yolk sack is determined 6 weeks and is 3 mm3 by the end of the first trimester, it increases up to 6 mm3, and then begins to decrease.
The doctor uses special tables or programs in which the dimensions and their corresponding deadlines. As a rule, three parameters of the fruit correspond to the same time and not have differences. The increase in the biparietal size indicates pathology of the fetus and untimely development of yolk sack an indirect indication of intrauterine infection, as it practically performs the function of the liver. With infections of the yolk SAC failed in its purpose and does not correspond to the expected sizes.
In the second and third trimester of pregnancy, the doctor at the ultrasound determines the size of the large bones (thigh, shoulder), which also correspond to a certain period of fetal development. Do not forget that the fetus is a living organism, not a programmed machine, so the size of the bones in a child whose parents are tall, be longer than the norm.
The first movement of the fetus occurs more frequently in nulliparous at term of 20 weeks, and those who mother is not the first time, perturbation felt at 18 weeks. From these rules there are exceptions, for example, in case reduced, a high sensitivity threshold, or if the woman is severely complete, the stirring she feels later.
All the collected data, an obstetrician-gynecologist determines the approximate duration of the pregnancy, but the more he relies on us data.