Oligohydramnios is the condition of having too little amniotic fluid.
What causes it?
Birth defects – Problems with the development of the kidneys or urinary tract which could cause little urine production, leading to low levels of amniotic fluid.
Placental problems – If the placenta is not providing enough blood and nutrients to the baby, then the baby may stop recycling fluid.
Leaking or rupture of membranes – This may be a gush of fluid or a slow constant trickle of fluid. This is due to a tear in the membrane. Premature rupture of membranes (PROM) can also result in low amniotic fluid levels.
Post Date Pregnancy - A post date pregnancy (one that goes over 42 weeks) can have low levels of amniotic fluid, which could be a result of declining placental function.
Maternal Complications - Factors such as maternal dehydration, hypertension, preeclampsia, diabetes, and chronic hypoxia can have an effect on amniotic fluid levels.
Ok, so now for the real post - Should you be induced because your doctor performs an ultrasound and says you have low fluid? Hmmmm..
It depends (as usual). How low is low? An AFI (amniotic fluid index) that is less than 5-6 = oligohydramnios, but...
On the other hand, a low AFI (oligohydramnios) at or near term may be an indication for delivery, either by induction or C-section. If there were to turn out to be a normal amount of fluid with rupture of membranes during an induction, then the low AFI that prompted the induction was either temporary or wrong. - http://www.gynob.com/biopamfl.htm
Notice the word temporary.
Notice the word wrong.
Some interesting information:
It is important for parents to know that this is likely an inaccurate assessment. What the ultrasound technician is doing could be compared to viewing an adult in a see-through plexiglass bathtub from below the tub. In such a scenario, it would be difficult to assess how much water is in the tub above the body that is resting on the bottom of the tub. You might be able to get an idea of the water volume by measuring how much water was showing below the elbows and around the knees, but if the elbows were down at the bottom of the tub, too, you might think there was very little water. This is what the technician is trying to do in late pregnancy—find pockets of amniotic fluid in little spaces around the relatively large body of an 8 lb. baby who is stuffed tightly into an organ that is about the size of a watermelon (the uterus). If most of the amniotic fluid is near the side of the uterus closest to the woman’s spine, it can not be seen or measured. - Gloria Lemay's Blog
Now, how do you know whether is a true case of "Oligo" or not? Well, there are several things that should be taken into account.
What gestation is your pregnancy?
If you are post dates, is the fluid "low" because the baby is big and the assessment is wrong? How do you tell? Why not get some IV fluids and then get another ultrasound? If you were borderline low, is it back into a normal range now? Maybe you could go home and drink drink drink and come back in the morning for another ultrasound?
Is the baby in any distress? Are you doing kick counts and getting 10 movements in an hour?
What if you are only 38 weeks and your AFI is showing 1? Way too low. And induction is probably very necessary.
So, here's the point. If your doctor says, "Your fluid is low, we need to induce.", don't blink blindly and say, "ok". Ask some questions.
What is my AFI?
Did you do a Biophysical Profile, and what are the results?
Can I get some fluids (IV, etc.) and retest?
Can low fluid be dangerous? Of course! And for that reason you should always pay attention to any diagnosis you are given. Oligohydramnios is more dangerous in the 2nd trimester. It is sometimes associated with other dangerous pregnancy complications. True low fluid in post dates pregnancies is associated with labor complications.
The problem is that it is very often hard to determine "oligo" with certainty.
As usual, be an active participant in your pregnancy and birth. There is nothing wrong with asking questions, even if you decide to take your doctors recommendations.