Q: What is amniotic fluid and is there a relationship between how much a mother drinks and how much amniotic fluid is in the uterus?
A: Amniotic fluid is composed of two major ingredients. The baby's urine is thought to be the major source of amniotic fluid. The baby's kidneys begin production at around 10 to 12 weeks into the pregnancy. Another source of amniotic fluid is fetal lung fluid. Lecithin and sphingimyelin are substances that are present in the baby's lungs while they are developing in the womb. Sometimes a small amount of amniotic fluid is aspirated from the uterus to test the ratio between these two substances. The L/S ( lecithin-sphingimyelin) ratio is considered a good indicator of the maturity of a baby's lungs. This might be done for someone who is having a repeat Cesarean section or someone who has been in preterm labor and a decision has to be made on when to take them off the drugs that are keeping them from going into preterm labor.
There is a wide range of amniotic fluid volumes during a normal human pregnancy. When there is too little or too much amniotic fluid this can be a sign that the pregnancy may have some complications. When there isn't sufficient amniotic fluid this is called oligohydramnios. Oligohydramnios complicates 3 to 5 percent of all pregnancies.
In all of the reference books that I used to research this subject, they all indicated that we still do not definitely know what regulates how much amniotic fluid is present in the uterus. There are many factors. We do know what normal amounts should be. The reason why a low amount of fluid is potentially dangerous is that is associated with stillbirth, fetal distress in labor, fetal anomalies and post mature babies.
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When the low amount of fluid is present for a long time it can lead to the baby not being able to move in the womb which can lead to orthopedic problems and lung growth development. Recent studies have shown that when a mother has a low amount of amniotic fluid, if she increases her fluid intake this can lead to an increase in amniotic fluid volume. The pregnant woman should increase her fluid intake whenever she feels thirsty (her body's way of giving her a signal about a need), when she exercises, in the summer when it is hot or if she should have diarrhea or lose fluids excessively. When a pregnant woman takes antihistamines she should first clear it with her physician and if it is OK then she should also increase her fluid intake. Another concern about a low amount of fluid is the possibility that the cord could be compressed.
Too much amniotic fluid is call polyhydramnios. Prior to the availability of ultrasound examination a diagnosis of polyhydramnios was made on the basis of an abnormal increase in the size of the uterus. Maternal diabetes mellitus is a known cause of polyhydramnios. When the baby has esophageal atresia (that is when the esophagus does not connect to the stomach) the baby cannot swallow, this may cause polyhydramnios, as will other upper gastrointestinal tract obstructive malformations. However these do not always lead to polyhydramnios but frequently they are related.
There are many mysteries as to why some people have complicated pregnancies and others do not. Amniotic fluid volume problems are not always easily explained. However we do know that if the mother has too little amniotic fluid, by increasing her fluid intake this can sometimes help increase the amniotic fluid. If there are no amniotic fluid problems and a mother increases her fluid intake it does not seem to affect the amniotic fluid volume. She just goes to the bathroom more.
The most important thing that all pregnant women need to do is to keep all of their prenatal visits with their medical provider. This helps assure a safe pregnancy for mother and child.
Katie Powers, R.N., is a board-certified lactation consultant and perinatal educator at Manatee Memorial Hospital's Family BirthPlace. Her column appears every other week in Healthy Living. Contact her at firstname.lastname@example.org.