Hormones – these are biologically active substances that are produced by the endocrine glands: the thyroid gland, the pituitary gland (it is located at the base of the brain), the adrenal cortex and the ovaries. During pregnancy, the body of the unborn child and the placenta are also involved in the production of biologically active substances necessary for the intrauterine development of the baby. Moreover, during this period, the concentration of hormones varies depending on the term of carrying the baby.
Therefore, assessing the risk of complications and the well-being of the future mother and her child, doctors are also guided by the level of biologically active substances in the woman’s body. Their shortage or excess is a signal of possible problems.
So what substances are responsible for the onset and successful development of pregnancy?
From the 4th day of the menstrual cycle in the right or left ovary among the follicles stands out the so-called dominant, in which the egg cell will mature. Under the influence of FSH – follicle-stimulating hormone, which is produced by the pituitary gland, – this follicle grows and, as it matures, it also begins to produce hormones – estrogens. Having reached a diameter of 15 mm, under the action of luteinizing hormone (LH), the dominant follicle is broken, and out of it comes a ripe egg, which is fertilized by spermatozoa.
The place where the egg came from, turns into a yellow body. It will produce progesterone under the influence of LH and prolactin.
Estrogens and progesterone prepare the uterine mucosa to “receive” a fertilized egg.
The yellow body “lives” only 12–14 days. If the pregnancy does not come, it will resolve, and menstruation will come in response to the decline in hormone levels. When fertilization occurs, the corpus luteum provides support for pregnancy by producing progesterone up to a period of 12 weeks.
Then this function will take over the placenta.
As soon as the fertilized egg has consolidated in the uterus and the egg has formed, the human chorionic gonadotropin (hCG), a hormone characteristic of developing pregnancy, begins to be produced. HCG, in turn, stimulates the corpus luteum so that it continues to produce progesterone.
It is possible to detect HCG in a woman’s body already from the 14th day after fertilization, even if there is still no menstruation delay. Normally, in a normally developing pregnancy, the level of this hormone should increase every 2–3 days. According to the dynamics of this indicator it is possible to judge the development of the ovum before the period of 8-10 weeks.
Then the level of hCG decreases and remains constant throughout the child’s birth. Low concentrations of hCG or lack of growth may indicate inferiority, as well as the death of the ovum.
This is the main hormone of pregnancy. The corpus luteum, by producing progesterone, provides for the needs of a developing pregnancy to about 10–12 weeks. Determining the level of progesterone during these periods, the doctor can assess the activity of the corpus luteum and, if necessary, prescribe progesterone replacement therapy.
Stimulates the production of progesterone hCG. The more active the gestational egg produces human chorionic gonadotropin, the better the yellow body produces progesterone.
From the 15th week on, progesterone synthesizes the placenta and the concentration of this hormone increases dramatically. At the end of pregnancy, progesterone levels are at 8–10 times more than in the first trimester.
Before childbirth, when the contractile activity of the uterus is important, its content drops sharply.
The main task of progesterone is to prevent the rejection of the endometrium and to prepare it for implantation of a fertilized egg. In addition, this hormone is a powerful relaxant.
It relaxes the uterus and at the same time the bladder and blood vessels, which is why a pregnant woman may have frequent urination and lower blood pressure.
Outside of pregnancy, they produce the ovaries, in the first half of pregnancy – the corpus luteum, and in the second – placenta. The most active of them is estradiol.
The lack of estrogen at the beginning of the child’s birth leads to impaired development of the precursor of the placenta – chorion –and abortion. In the second half of pregnancy, estrogen levels increase 12 or more times, since the adrenal glands of the future baby and placenta are connected to the production of these hormones.
In the future, throughout pregnancy, the level of estrogen should smoothly grow.
Before giving birth, in 39–40 weeks, the concentration of estrogen compared with the initial increases to 50–100 times. It is necessary for the preparation of the birth canal and the “maturation” of the cervix.
It is produced by the anterior pituitary gland. During pregnancy, prolactin production is stimulated by high levels of estrogen. The main task of this hormone is to start and maintain lactation. Prolactin also affects the formation of embryonic lung tissue.
At the beginning of pregnancy, the level of this hormone is low, it begins to increase in the second half of the child’s bearing, and in some women colostrum can be released from the nipples. Prolactin inhibits the activity of the ovaries, so when a mother breastfeeds a baby, she usually has no menstruation.
After six months, its effect weakens, and menstruation may reappear.
The posterior lobe of the pituitary is involved in its production. It is the most powerful stimulator of uterine contractions.
It is believed that before the birth of his level rises sharply, which is not quite so. In fact, before childbirth, it is not the hormone level that increases, but the number of receptors to it, that is, sensitivity to oxytocin increases.
Therefore, the longer the gestation period, the more clearly the woman feels the contraction of the uterus.
It is believed that the child gives the signal to the onset of labor, and it begins thanks to oxytocin and prostaglandins. By the way, “hormones of joy” influence the production of oxytocin. – endorphins and “hormone of fear” – adrenaline: the first increase the level of oxytocin, the second – reduces.
Conclusion: do not be intimidated during childbirth and do not shrink from fear when contractions begin, but enjoy the process of the birth of the baby.
If the generic activity is weak, oxytocin is used to stimulate it. After the birth of the baby, due to oxytocin, the uterus gradually returns to normal size.
By the way, it is lactation and the process of breast sucking by a child that increases the production of its own, endogenous, oxytocin and contributes to the contraction of the uterus.
These include 2 thyroid hormone: T3 (triiodothyronine) and Tfour (thyroxin), synthesized by the thyroid gland, and TSH (thyroid stimulating hormone), which is produced by the pituitary gland and regulates the functioning of the thyroid gland. Both thyroid hormones can be as in free (free T3 and tfour), and in related (common T3 and tfoura) with a protein state, but the biological activity of hormones is manifested only in the free fraction.
For normal, including the intellectual development of the future child, a strictly defined level of thyroid hormones is necessary. Low or elevated concentration increases the risk of abortion and can lead to impairment in the development of the baby. That is why all future mothers in the early stages of pregnancy determine the level of TSH and free Tfour.
These parameters are called the “mirror of the health of the thyroid gland.” Common T levels3 and tfour during pregnancy, normally always elevated, so it makes no sense to define them.
In order for these hormones to be sufficient, iodine must be administered to the woman’s body. So iodized products are a good prevention of problems with the intelligence of an unborn child and with pregnancy.