Gestational Age Does Not Match The Size Of The Fetus?
Hello, Today I have an ultrasound pregnancy and the results of an ultrasound show that my uterus is only 33 weeks old and my fetal weight is 2,100gr (if measured from 32 weeks old) but if the actual gestational age is at 34 weeks 5 days ( almost 35mgu) Please explain why this condition is dangerous and what is the solution. Thanks Sarni
Hello Sarni Mangopang,
Estimates of gestational age and estimated date of delivery can be determined by various methods based on the first day of last menstrual period (HPHT), measurement of uterine fundus height, and also ultrasographic examination of the uterus. The HPHT method is based on the first menstrual date, for example you menstruate in December from December 1-5, meaning that your HPHT is December 1 and the gestational age is calculated from that date to today, which means the estimated gestational age is 12 weeks 3 days. Also based on this HPHT method can vary 1-2 weeks from the time of actual conception, especially if you have irregular menstrual cycles.
Uterus fundus height measurement methods can be used for rough calculations of gestational age, for example in mothers who forget their HPHT. For example, at the age of 20 weeks, the top of the uterus can be touched as high as the navel, while at 36 weeks of pregnancy the height of the fundus of the uterus can be 1-2 fingers from the lower border of the breastbone. This method can also be inaccurate, if the size of the uterus is greater than the actual pregnancy, for example due to more than normal amniotic fluid (polyhydramnios) or twin pregnancies.
Determination of gestational age on ultrasonography utilizes the results of fetal anthropometric measurements, such as head circumference, distance from head to tip of buttocks, femur length, fetal abdominal circumference. Ultrasound examination performed in the third trimester (> 28 weeks) is no longer accurate to determine the age of the fetus or determine the estimated date of delivery. The reason is because the size of the fetus is usually already greater than the ability of a tool to measure all parts of the fetus, such as head circumference. The results of fetal age and fetal weight estimates also adjust the anthropometric measurements. For example, the estimated fetal weight is low so the age of the fetus displayed will be younger.
Ultrasonography performed in the third trimester generally aims to monitor fetal weight gain, placental condition, amniotic fluid volume, monitor fetal heart rate and fetal position. Variations in fetal age obtained from ultrasonographic results in the third trimester can range from + - 21-30 days from the actual age of the fetus.
The age of the fetus obtained from ultrasonography that is much younger (different> 21-30 days) from the actual gestational age (based on HPHT) can be caused by:
Intrauterine growth restriction: the baby does not grow according to the normal fetal growth curve. Can be caused by malnutrition in pregnant women, impaired blood-oxygen circulation to the fetus Wrong HPHT date Inaccurate ultrasound measurements In your case the difference is still 2 weeks from HPHT, this is natural, even if the fetal weight of the ultrasonographic examination results is still within limits normal for 32-34 weeks pregnancy. When the gestational age is> 37 weeks, it is expected that the fetus has reached> 2,500 grams. Even at birth, the baby will be tested for maturity to estimate the age of the baby whether or not enough in the womb based on physical maturity and neuromuscular maturity.
Please consult further with an obstetrician if you still want to ask more fully about the condition of your pregnancy. Thus the explanation from me, hopefully useful.