Is an amniotic fluid index of 90 mm at 40 weeks of pregnancy normal?

In general, at 40 weeks of pregnancy, which falls within the late stages of gestation, the normal amniotic fluid index (AFI) ranges from 80 to 180 mm. An AFI measurement of 90 mm at this stage is considered normal. The detailed explanation is as follows:

The amniotic fluid index is calculated by dividing the uterine cavity into four quadrants using the umbilical horizontal line and the abdominal midline as reference points. The deepest vertical pocket of amniotic fluid in each quadrant is measured by ultrasound, and the sum of these four measurements constitutes the AFI. Typically, at 40 weeks of gestation, a normal AFI ranges between 80 and 180 mm. Since an AFI of 90 mm falls within this normal range, it indicates a healthy level of amniotic fluid. If test results show abnormalities, it is important to determine whether there is polyhydramnios (excess amniotic fluid) or oligohydramnios (low amniotic fluid), both of which may require prompt medical intervention.

In summary, an amniotic fluid index of 90 mm at 40 weeks of pregnancy is normal. Routine care such as adequate rest and sufficient hydration is usually sufficient. However, if other discomforts or symptoms arise despite a normal AFI, it is advisable to consult a healthcare professional promptly.