After knowing what happens in week 1 and week 2 of pregnancy we continue to move forward with our series of posts about pregnancy week by week with the week 3 of pregnancy, the magical moment in which fertilization occurs.
We have commented that the duration of pregnancy is 40 weeks from the date of last menstruation (FUM) or 38 weeks from fertilization, so if we talk about a regular cycle of 28-30 days, in the week 3 of pregnancy It is when the union of the ovum and sperm happens that will start a new life. It's really when you get pregnant.
The magic of fertilization
If you have frequent relationships during this week (and the end of the previous one, always talking about a cycle of 28-30 days in which the fertile days are the central ones, from 13 to 17) you are likely to get pregnant.
As in this series we will talk about the weeks of pregnancy, we will assume that you have been fortunate that the 25% chance of becoming pregnant has fallen this month on your side. Always depending on the age of the woman; From 30 years of age the percentage drops to 15%, from 35 years to 8% and from 38 years, the probability is 3%.
You have been lucky enough to occur the miracle of fertilization. With each ejaculation an average of more than 200 million sperm are released, which should be able to survive the acid in the vagina, pass the cervix, fool the white blood cells that attack any invader of the body, trace the path dangerous and narrow of the fallopian tubes and finally reach the ovule.
The first sperm that reaches the ovule penetrates the external barrier until it enters its nucleus and achieves the fertilization that it gives rise to a new being.
At the moment when both gametes fuse, each contributing its 23 chromosomes, there is a unique genetic combination that determines the baby's DNA, and of course, its sex.
From ovule and sperm to embryo
Approximately 30 hours after joining the ovule and sperm begins cell multiplication, also known as segmentation.
He zygote resulting is divided into two, then four, eight, and so on, to form a mass of embryonic cells that make up the morula, which subsequently evolves to blastula or blast.
The blast is composed of two groups of cells, one external and one internal. The internal group will become the embryo, and the outside, in the membrane that will protect and nourish it during pregnancy, the placenta.
Depending on the number of fertilized eggs and when the zygote division occurs, there are different types of twins. They will be bicigotic twins or twins (triplets, quadruplets, etc.), that is to say two (or more) embryos with different genetic load that are gestated at the same time, or monozygotic twins, which will share the same genetic load as it has been the zygote which "by accident" has resulted in two or more embryos.
Between the fourth and seventh day after fertilization it is implanted in the womb, but that would be in the following week, the week 4 of pregnancyor, that is when menstruation should occur, but it won't because you are already pregnant.
First week of gestation
The week 3 of pregnancy is then the first week of baby's pregnancy, which will have a total of 38 weeks, 40 weeks or 280 days counting from the date of the last menstruation (FUM).
In the previous two weeks, the woman's body has been preparing to produce the magical moment in which a new life is lit.
