Two days ago, a little sister who had just become pregnant asked: "Since the fetus has lived in amniotic fluid for ten months, why does it not choke on water in amniotic fluid, and it will choke on water after birth?" "It's something that a lot of people are curious about.
The so-called amniotic fluid refers to the fluid of the amniotic cavity of the uterus during pregnancy. Throughout pregnancy, it is an indispensable and important component in maintaining the life of the fetus.
More than 90% of the amniotic fluid is water, and it also contains minerals, urea, uric acid, creatinine, fetal epithelial cells, etc.
There is so much water in the amniotic fluid, so how does the fetus breathe in it?
As we all know, oxygen is the gas that human beings rely on for survival, we usually inhale oxygen through the mouth and nose, and then input it into the lungs by the trachea, and enter the blood vessels through the balloons and bubbles in the lungs to transmit oxygen to the body.
The fetus does not breathe in the womb without the nose, the mother's oxygen enters the fetus through the placenta and umbilical cord, and the carbon dioxide produced by the fetal metabolism also enters the mother through the placenta and is excreted through the mother. Moreover, the lungs during the fetal period are solid and cannot perform respiratory functions.
After the fetus is born, with the first cry, the baby's airway is opened, the alveoli expand, and spontaneous breathing is formally established.
In addition, from 16 weeks of pregnancy, the fetus can practice amniotic fluid swallowing exercises in the uterine cavity to exercise respiratory function. But this breathing movement is not true fetal breathing.
Pregnant mothers will also ask such questions: "That baby swallows in amniotic fluid, will the amniotic fluid not be sucked in from the mouth and nose, choked into the trachea and lungs?" ”
In fact, there is no need to worry about Ha, because although the mouth will swallow amniotic fluid when the baby is in the stomach, but because the trachea and lungs at this time have some fluids, these liquids are used to protect the trachea and lungs, and the lungs at this time are solid, and the alveoli have not been opened, so there will be no cough.
Therefore, the fetus does not choke on water when living in amniotic fluid.
So why does the fetus need to live in amniotic fluid?
1. Keep the temperature in the uterine cavity constant, so that the metabolic activities in the fetus can be carried out under normal and stable conditions.
2. The fetus can rely on amniotic fluid to protect its fluid balance. When the fetus has too much water in the body, it is excreted into the amniotic fluid in the form of fetal urine; when dehydrated, the amniotic fluid can be swallowed in addition to moderate drainage to compensate.
3. Amniotic fluid has the effect of balancing external pressure, which can significantly reduce the impact of external violence and protect the fetus. Appropriate amounts of amniotic fluid also avoid fetal hypoxia caused by direct fetal compression of the uterine wall and the umbilical cord by the fetus.
4. At the time of labor, the uterus contracts, the intrauterine pressure increases, the amniotic fluid can conduct pressure on the uterine neck, the anterior amniotic fluid sac is formed before the fetal head is first exposed, the inside and outer mouths and the vagina are dilated, and the cervical and vaginal damage caused by the direct compression of the maternal tissue by the fetal limbs is too long.