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What happens in a woman's body during pregnancy?
Last reviewed: 04.07.2025
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Firstly, during pregnancy, the quantity and quality of hormones change. And you already know about one of them. This is chorionic gonadotropin. It is produced by one of the membranes of the fertilized egg after its implantation (fixation) in the uterus. It stimulates the corpus luteum to continue secreting progesterone - a hormone that ensures the maintenance of pregnancy. Progesterone is first produced by the corpus luteum, and then by the placenta.
Estrogens are also produced by the corpus luteum at the beginning of pregnancy, and then by the placenta after six to seven weeks. Their main role is to ensure the growth of the uterus, mammary glands, and fetus. The amount of estrogens is a criterion for assessing the function of the placenta and the development of the fetus. A sudden decrease in their amount is an indicator of a violation of this unity.
Placental lactogenic hormone affects fetal growth. It appears in the pregnant woman's blood five weeks after the last menstruation. If its amount is below normal, it is a risk for the developing child.
Oxytocin is produced by the pituitary gland and stimulates uterine contractions during pregnancy and labor. Early and increased secretion of it can cause premature labor.
In addition to the hormonal composition, changes also affect other organs and systems.
The uterus mass increases from 50 g in a non-pregnant state to 1 kg by the end of pregnancy. In addition to sheltering the embryo, the uterus has another role - to expel the fetus. Its muscle mass increases for this purpose. An enlarged uterus can lead to compression of the veins in the abdominal cavity, which worsens venous outflow from the lower extremities. This can cause varicose veins in the subcutaneous veins of the legs.
The respiratory system is also somewhat activated. Firstly, the developing fetus releases carbon dioxide (CO2) during its life cycle, which, when it enters the mother's blood, increases the overall level of CO2 in her blood. Because of this, the woman's breathing becomes deeper and more frequent. Secondly, the increase in the volume of circulating blood and the increased heart rate lead to faster and deeper breathing due to the constant ratio between the amount of blood flowing through the lungs and the volume of air inhaled. In addition, breathing becomes more frequent due to the increase in the size of the uterus, which presses on the lungs, reducing their volume.
The woman's weight increases by 10-12 kg. This is mostly due to the increase in fluid (up to 7 liters). If the mass increases too quickly and too significantly, then edema appears. This is a reason to sound the alarm and consult a gynecologist, since these are signs of toxicosis of pregnancy.
The cardiovascular system, or circulatory system, also undergoes changes: the volume of circulating blood increases, and the volume of plasma increases to a greater extent than the number of red blood cells. This is necessary for greater blood thinning (so that it flows better through the vessels). In this regard, pregnant women have a slightly lower hemoglobin (normally about 130 g / l, and in pregnant women - 105-110 g / l). At the same time, some gynecologists immediately make a diagnosis: anemia of pregnancy. (And it would be fine if they only made a diagnosis, but then they also begin to treat, and put you in the pathology department of pregnancy.)
The increase in the volume of circulating blood leads to greater than usual strain on the heart - tachycardia (increased heart rate) appears.
Blood pressure should remain the same throughout pregnancy. Therefore, if it increases towards the end of pregnancy, this is a reason to see a doctor. High blood pressure along with edema and the appearance of protein in the urine is a sign of toxicosis in the second half of pregnancy - preeclampsia.
Urination becomes more frequent due to the enlarged uterus, which begins to put pressure on the bladder.
Memory begins to suffer - along with the general increase in fluid in the body, its amount in the brain decreases. This causes a deterioration in memory, a decrease in some intellectual skills (it is more difficult to solve crosswords) and changes in the emotional sphere. At the same time, women very often want to sleep more. (And you should not deny yourself this.) And some want to cry all the time, they feel sorry for themselves - so "unhappy" and "abandoned" by everyone.