Amniotic fluid infections
Sterile amniotic fluid is important for your unborn baby's health, but it can become infected
What is amniotic fluid?
Amniotic fluid is usually sterile, and contained in the sac that surrounds your baby throughout pregnancy. It helps to protect and cushion, and also plays an important part in developing many of your baby's vital internal organs, such as the lungs, kidneys and gut.
The normal amount may vary, but there's usually a slow increase until about 36 weeks of pregnancy - then a slow decrease. Most women carry about 500 ml of amniotic fluid. The fluid is produced by the inner lining of the sac (amnion) as well as a contribution from your baby's lungs and kidneys - it is continually taken up by your baby's swallowing, and is also sent across the afterbirth (placenta) into your own circulation.
Occasionally, it can become infected, and the condition is called intra-amniotic infection or acute chorioamnionitis (AC).
Intra-amniotic infection/acute chorioamnionitis (AC)
This is a general term for infection - by bacteria of various types - of the amniotic fluid and membranes/sac (the placenta and sometimes the umbilical cord can also be involved) and is the most common cause of premature (pre-term) labour. This is because the infection weakens the membranes, resulting in their premature rupture.
The condition is said to occur clinically - where it can be demonstrated in some form - in between one to five births in every 200. Sometimes, there may even be a 'silent' amniotic fluid infection, where the mother-to-be has no evident symptoms. This may well explain some of the apparently 'unexplainable' causes for early losses of the developing pregnancy - in the form of a miscarriage.
Sometimes infection can affect the area of the attachment of the placenta and this will result in a reduced blood flow between the mother and her baby. This will affect the oxygen supply to, and the clearance of waste from, the baby, causing 'foetal distress' - a term so often heard during pre-delivery checks - and, once again, may precipitate premature labour.