During the entire pregnancy (with the exception of its earliest stages), the fetus is surrounded by amniotic fluid, or amniotic fluid. This environment, in which the baby hovers, like an astronaut in open space, not only protects him from external influences and maintains the necessary temperature, but also participates in the metabolism. Amount of amniotic fluid for nine months is constantly changing, but for each period of pregnancy there are norms of the volume of the amniotic fluid. Deviations in one direction or another may mean that the fruit is not all right.
Norm of amniotic fluid during pregnancy
The volume of amniotic fluid can be 600-1500 ml. The amount of an amniotic fluid less than 500 ml is considered to be anhydrous, more than 1,5-2 liters is a polyhydramnios. The ultrasound can help to make an accurate diagnosis.
During the ultrasound procedure, a specialist visually determines the amount of liquid by means of transverse scanning. If there is a lot of amniotic fluid, polyhydramnios are diagnosed, if there is little - water. At any deviation from the norm, the doctor conducts a more thorough examination - counting the index of the amniotic fluid. For this, the uterine cavity is conventionally divided into 4 equal parts by two lines, one of which passes vertically, along the white line of pregnancy, and the other - horizontally at the navel level. In each part, the maximum vertical pocket (free space between the uterine wall and the fetus) is measured, the results are summarized, yielding an index of amniotic fluid.
For each period of pregnancy there are norms of this indicator. For example, the index of the amniotic fluid is normal at a period of 22 weeks of 14.5 cm, or 145 mm (possible fluctuations should fit within a gap of 89-235 mm). And at 32 weeks the index of amniotic fluid will be 144 mm, with deviations in the range of 77-269 mm. Values for different terms of pregnancy can be found in the index table of the amniotic fluid index .
Amniotic fluid index - abnormalities
About deviations from the norm say in the event that the index of the amniotic fluid is lower or higher than indicated in the table values. Both polyhydramnios and oligohydramnios indicate possible pathologies in the development of the fetus or during pregnancy.
In case of polyhydramnios, the child often occupies an incorrect position in the uterus, and sometimes turns around the umbilical cord. Excess amniotic fluid can provoke their premature discharge and premature birth. Overgrowth of the uterus is worse in delivery and in the postpartum period, which can lead to weakness of labor and development of bleeding.
The main causes of polyhydramnios are:
- malformations (of the nervous and digestive systems) and chromosomal abnormalities of the fetus;
- fetoplacental insufficiency;
- pregnancy due to rhesus-conflict;
- infectious disease of the pregnant woman;
- diabetes mellitus in pregnant women.
If the index of the amniotic fluid indicates a marked lack of water in the second trimester of pregnancy, then a life-threatening situation may arise-the compression of the umbilical cord. In addition, the child is trapped in the uterus, his movements are limited. Such babies often have problems with the spine and hip joints after birth.
The development of malnutrition can lead to:
- malformations of the fetus (excretory system and kidneys);
- hypoxia and fetal hypotrophy;
- fetoplacental insufficiency;
- a premature pregnancy;
- infection;
- hypertensive disease of the pregnant;
- smoking.
Contrary to the beliefs of some women, the amount of liquid they drink does not affect the change in the volume of amniotic fluid in the placenta.