Obstetrician-gynecologist has at its disposal several ways to determine the duration of pregnancy Determination of gestational age - which method is most accurate? . First of all, it receives data in questioning the woman, then spends her inspection and, finally, uses data further examination, including ultrasound.

What makes a woman questioning

Gestational age can be determined according to the questioning women. First of all, the doctor finds out the date of the first day of the last menstrual period. Knowing this date is very important for that every woman should keep a diary of menstruation. The easiest way to determine the time of pregnancy if a woman has a regular menstrual cycle. Ovulation is known, is in the middle of the menstrual cycle and fertilization can occur only during the day after ovulation. When the 28-day menstrual cycle The menstrual cycle - that occurs in different phases?   Ovulation should occur 14-16 days after the first day of the last menstrual period, so by that date, added to two weeks.

In the second trimester gestational age can be determined by fetal movements: in nulliparous women the first stirring of the fetus occurs in 19-20 weeks, multiparous - at 17-18 weeks.

Clarified in the process of interviewing women information (history) allows you to compare pregnancy with a history with objective data obtained as a result of a pelvic exam.

What does a pelvic examination

What a woman is pregnant, a gynecologist may have to assume a period of one to two weeks, as the walls of the vagina and cervix become bluish tint. Furthermore, cervix loses its density and becomes softer.

Gestational age at the gynecological examination can be determined, since the five weeks. In this period the uterus is pear-shaped and round takes slightly increased. At eight weeks, the size of the uterus is approximately the size of a fist woman at 12 weeks - the size of a fist average man. By 12 weeks the top edge of the uterus (the bottom) is at the level of the pubis.

Starting from the second trimester (13 weeks), the uterus is already possible to probe through the abdominal wall and the gestational age is determined by the height of standing uterus above the pubis towards the navel and the xiphoid process (lower end of the sternum - the bone to which the ribs are attached in the front):

• at 16 weeks of gestation the fundus is located in the middle between the navel and the pubis or 6 cm above the pubis;
• 20 weeks fundus is at pubis or 20 cm above the pubis;
• 28 weeks - 25 cm above the pubis or 5cm above the navel;
• 32 weeks - in the middle of the distance between the navel and the xiphoid process, or at a distance of 30 cm from the pubis;
• 36 weeks - at the level of the xiphoid process, or at a distance of 35 cm from the pubis;
• 40 weeks fundus is lowered by 5 cm, and is located midway between the navel and the xiphoid process.

Pregnancy at 40 weeks is different from the 32-week around the circumference of the abdomen, the navel and the peculiarities of the size of the fetal head. Thus, at 32 weeks abdominal circumference less than 85 cm, no bulging stomach, fetal head diameter - no more than 10 cm. At 40 weeks, abdominal circumference greater than 90 cm, jutting stomach, fetal head diameter of approximately 12 cm.

In the 40 weeks of the height of standing uterus in nulliparous and multiparous women is different. So, in nulliparous women in whom the anterior abdominal wall muscles are not yet stretched, elastic, with omission of the stomach muscles do not give it to bulge forward, so the height of standing uterus corresponds to 32 weeks of pregnancy, or even be somewhat higher. Multiparous muscles of the front wall can not hold the uterus and it bulges forward, whereby fundal height may be even lower than at 32 weeks.

How else can you determine the time of pregnancy

There are various formulas for calculating the length of the pregnancy the fetus and the size of his head. For example, the method Jordania calculated by the formula X = L + C, where X - Term gestation in weeks, L - the length of the fruit in cm, C - diameter of the fetal head in cm.

Advanced version of the calculation - Skulsky method in which the gestational age calculated by the formula X = (L x 2) - 5/5, where X - the gestational age in months, L - the length of the fetus in the uterus multiplied by 2; number 5 in the numerator - the thickness of the uterine wall, the figure 5 in the denominator - a special factor.

Today, for the calculation of the pregnancy ultrasound is widely used. In the first trimester of pregnancy is measured by the distance between the coccyx and the neck of the fetus (coccyx-rump length), the second and third trimester - the diameter of the head, the length of the femur and the diameter of the stomach.

Using these methods, an obstetrician-gynecologist can determine the gestational age with errors up to a week, at a later date error may be larger, but allows the use of ultrasound in these cases to accurately determine the gestational age.

Galina Romanenko

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