The first month of pregnancy is a key period of pregnancy with different crucial stages: fertilization of course, then segmentation, implantation and the beginning of organogenesis. Under the effect of the hormones of pregnancy, the body of the future is already undergoing intense transformations in order to grow this new life.
Pregnancy weeks are counted from fertilization. The first month corresponds to the period of 1 to 4 weeks of pregnancy.
The weeks of amenorrhea (SA) are counted from the first day of the last period. Fertilization takes place around 2 weeks; the first month of pregnancy therefore corresponds to the period of 2 to 6 weeks.
The state of the fetus
Pregnancy begins during fertilization, namely the meeting of the oocyte and a spermatozoon. Once penetrated into the oocyte, the sperm nucleus increases in volume, just like the nucleus of the oocyte. The two come together and eventually merge: thus born the zygote, the first cell at the origin of all life. This egg carries all the genetic material necessary for the construction of a human being.
Thirty hours after fertilization begins segmentation: the zygote divides several times, while migrating to the uterine cavity. Nine days after fertilization, implantation takes place: the egg is implanted in the uterine lining.
At the third week of pregnancy, the egg has become embryo, her heart begins to beat. He then measures 1.5 mm and his cells continue to divide and begin to differentiate according to organs.
At the end of this first month of pregnancy, the embryo measures about 5 mm. He has a distinct “head” and “tail”, the buds of his arms, the inner ear, the eye, the tongue. Organogenesis has started and maternal-fetal circulation is in place. At 6 SA, pregnancy is visible on ultrasound and the heartbeat noticeable (1) (2).
Changes at the mom
As a life begins in her body, the mother ignores it at the very beginning. It is only with the delay of 4 SA rules that pregnancy is suspected. The future fetus has already two weeks of life.
Very soon, however, the mother’s body will undergo intense transformations under the effect of pregnancy hormones: the hCG secreted by the trophoblast (outer layer of the egg), which in turn keeps the corpus luteum active. (from the follicle) that secretes progesterone, essential for the good implantation of the egg.
This hormonal climate can lead to different signs of pregnancy:
an inflated and tense breast
a certain irritability
somnolence during the day
frequent urges to urinate
The uterus grows: the size of a nut outside pregnancy, it is now the size of a clementine. This increase in volume may cause tugging in the lower abdomen.
Things to do or prepare
Take a pregnancy test after a few days of delay
if the test is positive, make an appointment with a gynecologist or midwife. The first compulsory prenatal examination (3) must take place before the end of the first trimester but it is advisable to consult before.
continue vitamin B9 supplementation if prescribed during a pre-conception visit
Even if the pregnancy is not known at first, as a precaution it is necessary to avoid risky practices: consumption of alcohol, drugs, tobacco, exposure to X-rays, medication. This is all the more important in the stage of organogenesis, the embryo is very sensitive to teratogens (substances that can cause malformations).
if bleeding, severe pain in the lower abdomen or on one side, it is important to consult to rule out any suspicion of miscarriage or ectopic pregnancy.
If this has not been done during the pre-conceptional assessment, it is advisable to perform an oral assessment to avoid complications during pregnancy.