Amniotic fluid: what is this fluid that envelops the fetus and what is it for
Amniotic fluid is a special liquid that protects the baby and that increases with its growth: it makes you feel that your baby is safe in your tummy protected and muffled from the outside world. The analysis of the amniotic fluid can reveal to you fundamental details about pregnancy. If you are expecting, find out how the baby grows in your belly, month after month, watching this really exciting video and foretaste the pleasure of hugging it!
The functions of the amniotic fluid: many and important
The amniotic fluid protects the fetus from external and internal agents (shocks, noises, temperature changes, infections, pressure on its anatomical structures); it allows him to develop his lungs, his stomach, his intestines, his muscles and his bones, without crushing and distortion, it works as a thermal insulator and contributes in part to its nourishment. Furthermore, with the enzymes it contains, it protects the fetus from possible infections and therefore also has an "important antibacterial function. The molecules of the foods ingested by the mother pass into the amniotic fluid and will influence her food tastes after birth. In this liquid, the baby is taken." moves in total freedom; only in the last few weeks does it position itself upside down. It is a special and perfect element, in which the child lives preparing to come into the world. And the mother warns that her little one is safe and protected in this comfortable environment created by nature for him. Amniotic fluid prevents the baby from squeezing the umbilical cord and at the same time also protects the mother's internal organs from fetal movements. This important fluid forms from 4 to 9 months of pregnancy above all the fetal kidney with a production of sterile urine, but also the placenta, the fetal skin, the respiratory and urinary tract are involved in this operation. ido during pregnancy must always be in the right amount for everything to go well for the fetus. The child continuously ingests liquid, which is then absorbed by his intestine and thus balances the amount of urine he produces, himself regulating the balance of the amniotic fluid.
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The amniotic cavity in which the fetus and this liquid are received develops in the first weeks of pregnancy. This cavity, delimited by the amnion or amniotic membrane, gradually expands until it comes into contact with the chorion, the outer membrane that surrounds and protects the embryo. Before the third or fourth month of pregnancy, amniotic fluid is mainly obtained from the passage of the fluids contained in the blood of the placenta (transudation) towards the amniotic sac. Later, it comes mainly from the fetus, its urine and its secretions of the respiratory system. The amniotic fluid always increases up to the eighth month, and then remains more or less the same until the end of gestation, when there is a marked decrease with an increase in the volume of the fetus. During the last three months of gestation the ratio between the two volumes decreases in favor of the fetal one. Amniotic fluid contains important stem cells, which can be stored in so-called stem cell banks in the hope that science can use them to find the right cure for serious, yet incurable diseases.
The "amniocentesis: an" invasive investigation of the amniotic fluid
Amniocentesis is an invasive technique for cytogenetic investigations, biochemical investigations for the diagnosis of cases of inborn errors of metabolism, dosage of alpha-fetoprotein, DNA analysis for the diagnosis of monogenic hereditary diseases that reassure the health of the fetus, to exclude all possible chromosomal abnormalities of the fetus, such as Down syndrome, genetic diseases, such as cystic fibrosis or infectious diseases. It is practiced by aspirating some amniotic fluid to be analyzed with a needle inserted into the mother's belly. The assessment of the amount of amniotic fluid is done through ultrasound. At the end of gestation it ranges from 8 to 20 cm. An excessive amount of fluid, the so-called polyamnios, could lead to suspect a fetal problem (related to the digestive system that makes it difficult to take fluids to balance the kidney) or a pathology of the mother, for example gestational diabetes, which alters the metabolism of the baby, causing him to produce an exaggerated production of urine, a twin or multiple pregnancy, difficulty in swallowing and absorption by the fetus, perhaps due to intestinal obstruction. If the liquid is less than normal, then oligoamnios could suggest suffering of the digestive system, placental dysfunctions, fetal abnormalities that prevent urine production, rupture of the amnion or pregnancy beyond the normal 40 weeks. Amniocentesis has a 0.5% risk of spontaneous abortion.
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When should this test be done?
Amniocentesis, that is to say the removal of amniotic fluid or to analyze it, is usually carried out between the 16th and 18th week of pregnancy. In this period, in fact, cells of epithelial tissues of the lower pathways can also be found in the amniotic fluid. urinary and trachea, which can give indications on chromosomal anomalies; the dosage of alphafetoprotein allows instead to exclude particular malformations such as anencephaly, spina bifida or meningocele. It is recommended if you fear that the fetus has an infection or pathologies not yet diagnosed, for the age of the mother, if over 35 years, for a previous pregnancy with chromosomal or genetic disease or for malformations seen during ultrasound. To assess the level of lung maturity can be carried out after the thirty-second week. The test does not require special preparation, but it may be necessary to do it with an empty or full bladder depending on the gestation period. The liquid is aqueous white to opal yellow in color and contains hormones, antibodies and proteins. It is renewed continuously: the fetus ingests it and eliminates it in the urine.
Before performing an "amniocentesis it is good to thoroughly evaluate the advantages and disadvantages of this diagnostic technique in an interview with the specialist. It is still routinely practiced today, but scientific progress in the medical field is reducing the need. In fact, now. to analyze the DNA of the circulating fetal cells it is only necessary to take a blood sample from the mother before the tenth week of pregnancy, a test that allows to exclude chromosomal abnormalities such as Down syndrome (trisomy 21), Patau (trisomy 13) and Edwards (trisomy 18). The transabdominal examination under ultrasound control is indicated for the study of the chromosomes of the fetus. In the human body there are 23 pairs of homologous chromosomes deriving in equal numbers from the father and mother. However, there may be chromosomes with anomalies in number or structure. The best known is Down Syndrome or Mongolism. In addition to those we have already mentioned before, we reorder the Monosomy X (S. of Turner). Before the "amniocentesis" an ultrasound is performed, to confirm other factors, such as number of fetuses, gestational period, quantity of amniotic fluid, position of the placenta . The amniocentesis is however performed under ultrasound control to avoid damage to the fetus, very rare anyway. Afterwards, 15 cc of amniotic fluid is aspirated, which will be analyzed in the laboratory. When it comes to twin or multi-twin pregnancies, if the operator is experienced and skilled with a single puncture in the uterus, he can carry out both samples, even though there are two different amniotic sacs.
The waters have broken!
When the woman is about to give birth, the amniotic sac breaks (in common parlance it is said "the waters have broken"). This break stimulates the prostaglandins, which initiate contractions and therefore dilation. Rupture of the amniotic sac can occur before going into labor or during labor. From the breaking of the waters you can wait from 12 to 24 hours, hoping for a natural start of labor. Otherwise, labor is induced through the safe and frequently used IV infusion of oxytocin. The amniotic fluid reaches its maximum volume, about 800 ml around the 34th week of gestation. At this point, the rupture of the amnion or part of it could occur and the woman begins to lose a warm, odorless and colorless liquid. A clear signal that the birth is imminent. Sometimes, especially in the presence of bacterial infections, the membranes can rupture before the 38th week of gestation; in these cases we speak of premature rupture of the membranes. Regardless of the period in which it occurs, after the breakdown of the water it is very important that the woman goes to the hospital to prevent the risk of infections.
Vernier
During gestation the fetus produces a lot of sebum, which goes to protect its skin. Yes, a layer of fat from prolonged contact with amniotic fluid, this layer is called vernix, smooth, but not oily, which, like a special cream, protects the skin of newborns, even when they are in the mother's womb; it is produced by the sebaceous glands and is composed of water and proteins. fats and vitamins. In addition to its protective function, it also has a moisturizing effect, defends the baby from viruses, bacteria and fungi, provides him with vitamin E. Furthermore, after delivery, thanks to this sebaceous film, the baby suffers less attacks from the external environment. In fact, while before the newborn child was thoroughly washed with the bath also to remove this cheesy varnish, perfumed and powdered to show it to the new mother, today in an era in which there is a lot of belief in skin to skin and the newborn baby rests on the mother's abdomen even before cutting the umbilical cord, this protective patina is not removed immediately after delivery, but it is expected that after days of delivery it will reabsorb itself autonomously.
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