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Amniotic fluid is removed from the mother by an amniocentesis procedure, where a long needle is inserted through the abdomen into the amniotic sac, using ultrasound guidance such that the fetus is not harmed. Amniocentesis is a low risk procedure, with risk of pregnancy loss between 1 in 1,500 – 1 in 700 procedures.
In the first trimester, the main sources of amniotic fluid are fetal lung secretions, transportation of maternal plasma across the fetal membranes, and the surface of the placenta. By the second trimester, the fetal kidneys start to produce urine which becomes the main source of the amniotic fluid for the remainder of the pregnancy. [4]
The lecithin–sphingomyelin ratio is a marker of fetal lung maturity. The outward flow of pulmonary secretions from the fetal lungs into the amniotic fluid maintains the level of lecithin and sphingomyelin equally until 32–33 weeks gestation, when the lecithin concentration begins to increase significantly while sphingomyelin remains nearly the same.
3. To check the color of the fluid. If there is a suspicion of the presence of meconium (the contents of the baby's bowel), certain preparations must be made. Suctioning must be set up and more personnel are required to be in attendance. 4. To avoid having the baby aspirate the contents of the amniotic sac at the moment of birth.
The fetal membranes separate maternal tissue from fetal tissue at a basic mechanical level. The fetal membrane is composed of a thick cellular chorion covering a thin amnion composed of dense collagen fibrils. The amnion is in contact with the amniotic fluid and ensures structural integrity of the sac due to its mechanical strength.
Some degree of weight gain is expected during pregnancy. The enlarging uterus, growing fetus, placenta, amniotic fluid, normal increase in body fat, and increase in water retention all contribute weight gain during pregnancy. The amount of weight gain can vary from 5 pounds (2.3 kg) to over 100 pounds (45 kg).
Usual follow-up steps include (1) a prenatal ultrasound exam to look for fetal abnormalities and/or (2) measurement of AFP in amniotic fluid obtained via amniocentesis. Maternal serum AFP (MSAFP) varies by orders of magnitude during the course of a normal pregnancy. MSAFP increases rapidly until about 32 weeks gestation, then decreases gradually.
The amniotic fluid increases in quantity up to the sixth or seventh month of pregnancy, after which it diminishes somewhat; at the end of pregnancy it amounts to about one liter. [ citation needed ] The amniotic fluid allows the free movements of the fetus during the later stages of pregnancy, and also protects it by diminishing the risk of ...