10th week of pregnancy

The condition of the fetus at 1 month of pregnancy

Pregnancy begins during fertilization , namely the meeting of the oocyte and a spermatozoon. Once inside the oocyte, the nucleus of the spermatozoon increases in volume, just like the nucleus of the oocyte. The two come together and end up merging: thus the zygote is born, the first cell at the origin of all life. This egg carries all the genetic material needed to build a human being.

Thirty hours after fertilization begins segmentation: the zygote divides several times, while migrating towards the uterine cavity. Nine days after fertilization, implantation takes place: the egg implants itself in the uterine mucosa.

At the 3rd week of pregnancy , the egg has become an embryo, her heart begins to beat. It then measures 1.5 mm and its cells continue to divide and begin to differentiate according to the organs.

At the end of this first month of pregnancy, the 1-month-old embryo measures approximately 5 mm. It has a distinct “head” and “tail”, the buds of its arms, inner ear, eye, tongue. Organogenesis has started and the foeto-maternal circulation is in place. Pregnancy is visible on ultrasound at 1 month and heartbeats perceptible (1) (2).

Changes in the 1 month pregnant mom

As a life begins in her body, the mother ignores it throughout the first month of her pregnancy . It is only with the delay of menstruation at 4 SA that pregnancy is suspected. The 1-month-old embryo , which will become a fetus, is already two weeks old.

Very quickly, however, the mother’s body will undergo intense transformations under the effect of pregnancy hormones: hCG secreted by the trophoblast (outer layer of the egg) which in turn keeps the corpus luteum active. (from the follicle) which secretes progesterone, essential for the good implantation of the egg.

This hormonal climate can already lead to various pregnancy symptoms during the first month :

  • nausea
  • sensitivity to odors
  • a swollen and tense chest
  • some irritability
  • drowsiness during the day
  • frequent urination

The uterus grows: from the size of a walnut outside of pregnancy, it is now the size of a clementine. This increase in volume can cause tightness, even pain in the lower abdomen during the first month of pregnancy . 

The belly of the 1 month pregnant woman is not yet visible, but it will gain volume month by month throughout the pregnancy.

1st month of pregnancy, things to do or prepare

  • Take a pregnancy test after your period is a few days late
  • 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 1st trimester but it is advisable to consult before.
  • continue vitamin B9 supplementation if prescribed during a pre-conception visit


  • 1 month pregnant , in case of bleeding, severe pain in the lower abdomen or on one side, it is important to consult in order to rule out any suspicion of miscarriage or ectopic pregnancy.
  • if this was not done during the pre-conception check-up, it is advisable to carry out an oral check-up in order to avoid any complications during pregnancy.
  • Even if the pregnancy is not known at the beginning, as a precaution it is advisable to avoid risky practices: consumption of alcohol, drugs, tobacco, exposure to X-rays, taking medication. This is all the more important since at the stage of organogenesis , the embryo is very sensitive to teratogenic agents (substances that can cause malformations).
See also  10 things not to do when you are pregnant

In fact, alcohol consumption during pregnancy can lead to fetal alcohol syndrome, which can disrupt the growth of the 1-month-old embryo . This syndrome leads to malformations, developmental disorders at the neurological level and growth retardation. The baby is more likely to be born prematurely. Tobacco is harmful for everyone and even more so for pregnant women, even 1 month , and the foetus. Before getting pregnant, smoking decreases fertility. During the first month of pregnancy, smoking increases the risk of miscarriage and premature birth. In addition, smoking must be prohibited throughout these 9 months, but in particular for the 1 month fetus.. It compromises his good in-utero development. The future baby can be born with malformations. In addition, smoking during pregnancy increases the risk of respiratory problems in the baby after birth. 

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