Low Amniotic Fluid

According to the March of Dimes, approximately 8 percent of women develop oligohydramnios, or low amniotic fluid, at some point during their pregnancy. In women who are still pregnant two weeks past their due date, the rate jumps to 12 percent.

During pregnancy, your body produces an increasing amount of amniotic fluid until about 28 to 32 weeks, at which time you have about one quart. You maintain this level of fluid until 38 to 40 weeks, when your baby is considered full-term and the fluid level normally begins to decrease. Amniotic fluid is essential for proper fetal development and provides your baby with protection and buoyancy. The effect of oligohydramnios on the baby depends on the cause, the stage of pregnancy during which it occurs, and how little fluid there is.

If it occurs in the first half of the pregnancy, oligohydramnios can cause fetal abnormalities of the lungs and limbs, poor fetal growth, and increases the risk of miscarriage, preterm birth and stillbirth. Your baby "breathes" the fluid into its lungs and swallows it, promoting healthy growth of his or her lungs and gastrointestinal tract. Too little fluid for a prolonged period may cause abnormal or incomplete lung development, called pulmonary hypoplasia. The amniotic fluid also promotes normal development of muscle and bone by allowing your baby to move around within the uterus.

Oligohydramnios that occurs late in the third trimester may cause the umbilical cord to become compressed during labor and delivery, which cuts off the baby's oxygen supply. It may also cause your baby to breathe in thick meconium (your baby's first bowel movement) during or shortly after birth. The inhaled meconium can irritate and partially or completely block your baby's airways, making it difficult for her to breathe. You may have a higher risk of developing oligohydramnios if you have certain conditions; however, the majority of pregnant women who develop this condition have no identifiable risk factors. Some of the most common causes of oligohydramnios include:

Leaking or ruptured membranes

A small tear in your amniotic sac can allow some fluid to leak out. This can happen at any point in your pregnancy but it is more common as you approach delivery. You may notice you are leaking fluid, or your practitioner may discover it during an exam. Occasionally, a tear will heal on its own, the leaking will stop, and your fluid will return to normal levels.

Placenta problems

A problem with your placenta, such as a partial abruption, may prevent it from supplying enough blood and nutrients to your baby, which can cause him or her to stop recycling the fluid, and levels to drop.

Certain medical conditions

Certain maternal health conditions, such as chronic high blood pressure, preeclampsia, diabetes, and lupus, can cause your amniotic fluid levels to be low.

Carrying twins or multiples

If you are carrying twins or multiples, you are at an increased risk for low fluid levels. Oligohydramnios is common in the case of twin-to-twin transfusion syndrome in which one twin suffers from too little amniotic fluid while the other twin creates too much.

Fetal abnormalities

Low amniotic fluid levels in your first or second trimester may be caused by a fetal abnormality. For instance, if your baby's kidneys aren't developing properly or did not develop at all, or his urinary tract is blocked, your baby won't produce enough urine to maintain a healthy level of amniotic fluid.

Post Date Pregnancy

Doctors use various methods to measure amniotic fluid levels, but the most common test is an amniotic fluid index evaluation, or deep pocket measurement. Your doctor will measure the largest pockets of amniotic fluid in four different sections of your uterus and evaluate the combined measurements against the amniotic fluid index (AFI). A normal level for a woman in her third trimester is between 5 and 25 centimeters (cm). Oligohydramnios is suspected if an AFI shows a fluid level of less than 5 centimeters (or less than the 5th percentile), the absence of a single fluid pocket 2 to 3 cm in depth, or a fluid volume of less than 500mL at 32 to 36 weeks gestation. The treatment for oligohydramnios varies depending on gestational age. If you are not full tem yet, your doctor will monitor you and your fluid levels very closely and may perform tests such as non-stress and contraction stress tests to monitor your baby's activity. If you are close to full term, your doctor may recommend you be induced and deliver your baby early. Other treatments include:

• Amnio-infusion during labor using an intrauterine catheter. This process injects fluid directly into the uterus to help cushion the umbilical cord during delivery and lower the chances of a cesarean delivery.
• Injection of fluid prior to delivery through amniocentesis. Although oligohydramnios often returns soon after this procedure, it can help your doctor visualize the fetal anatomy and accurately determine fetal development.
• Maternal re-hydration with oral fluids or IV fluids has shown to help increase amniotic fluid levels.

If you are diagnosed with oligohydramnios, it is important that you continue to eat well, drink lots of fluids (water is best), rest as much as possible, avoid smoking and report any signs of preterm labor to your health care provider right away.