Amniotic fluid is an important part of what keeps your baby protected in the womb. The amniotic fluid is created as soon as 12 days after the baby is conceived. In the beginning the amniotic fluid consists of water from the mother, but from around 20 weeks it is primarily composed of fetal urine. As the baby grows it will begin to move around in the amniotic fluid, and during the second trimester it will also begin to breathe and swallow the amniotic fluid.
There are cases where there can be too much or too little amniotic fluid, putting the baby in danger. Not enough amniotic fluid is referred to as oligohydramnios, too much fluid is called polyhydramnios.
What Exactly Is Polyhydramnios?
This is the condition where there is too much amniotic fluid in the womb. The amount of fluid in the womb can be measured a few different ways, usually using the amniotic fluid index which uses deep pocket measurements to find out approximately how much amniotic fluid is in the womb. The following can indicate high levels of amniotic fluid:
- Fluid level exceeding 25cm
- Fluid pocket 8cm or more in diameter
- Volume of over 2000mL
Polyhyrdamnios is a fairly rare condition, only effecting about 1-2% of pregnancies, and in most cases involve only slightly above normal levels of amniotic fluid.
Various conditions can cause high amniotic fluid levels, such as the following:
Congenital Defects: Usually higher levels of fluid mean an increase in the chance of a congenital defect. The build up occurs because the defect restricts swallowing which leads to a build up of amniotic fluid. Intestinal tract problems and neurological issues can also be the cause.
Rh Factor: In North America this isn’t a problem, since screening is done prior to the delivery of the first baby.
Diabetes: If the mother has diabetes this can lead to an increase in amniotic fluid.
Twing-to-twin transfusion syndrome – This complication only occurs in pregnancies involving identical twins, where issues with blood vessels and their connection to the placenta result in one baby getting too much blood while the other gets too little.
Other Reasons: Up to 65% of cases of polyhydramnios do not have a specific cause.
Risks Of Polyhydramnios
In most instances the higher levels of amniotic fluid in the womb are not enough to cause problems, but in cases where the level are extremely high there are the following risks:
- PROM – Premature Rupture of Membranes
- Placental abruption – placenta detaches from the uterine wall
- 26% chance of preterm labor and delivery
- IUGR – Intrauterine Growth Restriction which can lead to skeletal malformation
- Stillbirth – the risk for still birth in a normal pregnancy is 2 in 1000, with polyhydramnios the risk increases to 4 in 1000
- Increase in chance for a cesarean delivery
- Hemorrhage after delivery
Treatments For Polyhydramnios
Luckily the treatments designed to reduce polyhydramnios are simple and in most cases do not complicate the pregnancy, although close monitoring is required. Generally frequent sonograms are used to measure fetal growth at regular intervals, along with a biophysical profile and fetal assessment. Treatments include:
- Prior to 32 weeks: medication to reduce fluid levels, which is up to 90% effective.
- Amnioreduction: a process used through amniocentesis to remove excess fluid. However there is the possibility that fluid will just build up again, and this procedure carries a few risks.
- Delivery of the baby.