First of all, there can be a reading error by the ultrasonologist.
If the ultrasound measurement of the amniotic fluid index (AFI) is less than 5cm, this is considered as low leve of amniotic fluid. To treat this, you have to find the cause. The causes can be fetal or maternal. Fetal causes include bilateral renal agenesis (Potter's syndrome, kidneys not formed), polycystic kidneys, or obstruction to genitourinary system. Maternal causes include dehydration, uteroplacental insufficiency, or use of angiotensin converting enzyme. Cause can also be idiopathic or no cause. Ultrasound can detect most of these abnormalities. Usually increasing mother's fluid intake by mouth or through intravenous route improves the amniotic fluid level. Chances of fetal abnormalities are high. If no abnormalities are detected, then the pregnancy can carry forward and you can give birth to a normal baby. Please discuss you’re your doctor. Take care!