Each month, the ovaries release an egg, approximately 14 days before the first day of the period occurs. It is what is known as ovulation, and consists of the natural detachment of a mature egg from the ovary which, after passing through the fallopian tube, passes to the uterus, at which time it can be fertilized.
At the time of ovulation, when unprotected sex is maintained, the sperm can join with the ovum, and when this occurs it is what is medically known as fertilization. That is to say, it is the moment in which the sperm and the ovum meet, and a single sperm penetrates in the ovum, giving rise to an embryo.
Therefore, if you have unprotected sex, the chances of the woman becoming pregnant can occur at any time from 5 days before the day of ovulation, and including the day of ovulation itself.
When this occurs, the fertilized egg travels through the fallopian tubes until it reaches the uterus, where it attaches to the wall (this is what is known as implantation). It is in this place where the embryo begins to create and develop.
This fecundation takes place in the Fallopian tube. In fact, when the ovum leaves the follicle it takes less than 24 hours to reach the fallopian tube.
If we take into account that from the vagina to the fallopian tube there are about 18 centimeters long, it is normal that only the most capable and better-looking sperm get to do the whole journey. Even when this occurs, the sperm must fertilize the ovum through the egg wall with its head.
When this is achieved, the so-called zona pellucida hardens almost immediately, in order to prevent any other sperm from entering the interior of the ovule.
Cell multiplication and the birth of the embryo
When the sperm and the ovum come together, a new and unique cell is formed, destined to become the baby. It is what is known as the embryo.
The embryo begins to divide. The first cell is divided into two cells, and then those two cells are divided into four ... and so on in succession. At the same time, the embryo begins to migrate through the fallopian tube until it reaches the uterus.
The different hormonal changes that occur in the woman's body during the release of the ovum affect the endometrium (uterus membrane), which is prepared in order to accommodate the embryo in case of conception.
How does the embryo grow inside the uterus?
Once implantation occurs (which is when the embryo detaches from its cortex and adheres to the membrane or uterine wall), it begins to produce human chorionic gonadotropin (hCG for its acronym in English).
Given that hCG is a hormone produced by the embryo itself from the moment in which implantation occurs, it tends to be detected first in the mother's blood. For this reason during the first days after conception, the only sure test capable of confirming pregnancy is the beta hCG exam .
They have to spend a few more days for part of this hormone to pass to the kidneys, and finally end up in the urine (at which time it is safe to perform a urine test ).
What changes occur in the body of the future mom?
During the first weeks of pregnancy, the most common is that you do not look different. Yes, it is possible that little by little they can begin to emerge first symptoms of pregnancy , but at the moment it is still early for your body to notice some drastic change.
There are moms who say that, in the first days of pregnancy, they feel internally as if a major change occurs inside them. As if, somehow, they felt 'connected' to that embryo that is beginning to grow and develop within them. But although these changes may or may not be felt internally, externally during the first weeks there is no change.
What is the best age to try the conception?
It is well known that the age at which a woman becomes pregnant with her first baby is increasing in practically all countries, especially among those considered as developed countries. Specifically, while in Germany it can reach 30 years, in the United States it tends to be somewhat smaller (around 25 years).
If we bear in mind that a woman's fertility begins to fall little by little as she ages, it is normal that many women who want to have children worry about the age factor.
It is considered that the best age to attempt conception is between 23 and 31 years. During this stage, it is considered that the woman has reached her fertility peak. So, from then on, fertility begins to decline little by little.
For example, starting at age 31, fertility tends to begin to fall by around 3% each year. Thus, at 40 years, the average probability that a woman can achieve pregnancy with a cycle is only 5%.
Probabilities of getting pregnant according to the number of months trying to conceive
In the following table we indicate what are the probabilities of a woman getting the conception, and therefore becoming pregnant, the function of the number of months trying to conceive: