It coincides with week 10 of embryo development. The embryonic period is beginning, all the organs and systems of the embryo have already formed. From now on, the baby's organs enter a phase of intense growth and maturation. to begin functioning correctly. Although fewer malformations occur in the baby during this new period, we must not let our guard down: it remains essential to maintain all the recommendations regarding healthy nutrition, responsible use of medication y avoid toxins that they indicated to us at the beginning of the pregnancy.
Week 12 of pregnancy How is the baby?
At 12 weeks of pregnancy, the fetus measures around 6 centimeters from head to rump. and weighs between 9 and 14 grams. The baby's appearance is entirely human: the head, chest, abdomen, and limbs are clearly distinguishable. Although the proportions are not yet balanced, the The head represents approximately half of the total length.From now on, the development of the head becomes slower compared to the rest of the body, which will grow very quickly.
The baby's skin is still very thin and reveals the blood vessels that's underneath. The muscles are formed, but they need exercise to strengthen, so the baby is already actively moving inside the uterus: It stretches, curls its legs, moves its arms, turns its head, and opens and closes its mouth.These movements are frequent, even if the mother doesn't yet notice them. This exercise contributes to muscle development and neuromuscular maturation.
On the face, the eyes, which initially formed on the sides of the head, are now almost in their final position, although the eyelids remain fused To protect the surface of the eye, the eyes will not open until well into the second trimester. The ears are in the process of moving into their final position on either side of the head, so they may still appear somewhat low or primitive, which is completely normal at this stage.
The fetus's internal organs continue to mature at great speed. The intestines, which until now were partially within the umbilical cord, are moving into the abdominal cavity, where there is now space for them. The digestive system, which began as a simple tube, has grown and curved until it has differentiated into the esophagus, stomach, small intestine, and large intestine. The baby's kidneys have already begun to produce urine., which is stored in the bladder and released into the amniotic fluid; this swallowing and elimination cycle contributes to the development of the digestive and urinary systems.
The lungs are still developing: the airways branch out and the lungs continue to form. bronchiolesalthough it will still be many weeks before they are ready to breathe air. They also form vocal chordsFingernails and toenails begin to appear, and a fine line begins to form. very soft hair in certain areas of the body. The pituitary gland initiates the production of several important hormones that regulate many bodily processes.
As for the external genitalia, they have already differentiated into male or female. In male fetuses, the development of the... scrotum and the glans of the penis; in female fetuses the clitoris, labia majora, and labia minoraAlthough the general shape is defined, the size is still small and the position of the fetus can make it difficult to see them clearly, so It is not always possible to determine the baby's sex with certainty in this week's ultrasound..
At this stage the placenta is already well formed and secretes a sufficient amount of progesterone and other hormones to maintain the pregnancy and ensure the proper exchange of nutrients and oxygen between the mother and the baby.
What does the mother notice in the 12th week of pregnancy?
Generally, nausea and vomiting They will gradually decrease in intensity starting this week. A period of greater physical and emotional tranquilityIt can even be scary to feel so well after a first trimester filled with discomfort. However, every pregnancy is different: some women continue to experience digestive symptoms for several more weeks.
It's normal that you don't yet have a very obvious baby bump, although it's common to start noticing that the The waistband of the pants is tight And it's uncomfortable. The uterus begins to protrude above the pelvis, and that can result in subtle changes in the shape of the abdomen.
You may notice a feeling of sharp pains or tightness in the lower abdomen and swelling. This is due to the growth of the uterus and the distension of the ligaments that hold it upUnless intense, persistent pain, bleeding, or general malaise occurs, these discomforts are usually completely normal and temporary.
Hormonal changes can also produce other symptoms: breast enlargement and increased sensitivity, increased sebum production in the skin (with a brighter appearance, although sometimes with some acne), more sensitive gums that are prone to bleedingNasal congestion and even minor nosebleeds. Increased blood flow and hormonal activity can also promote the appearance of small, visible blood vessels on the skin and increase the risk of sun spots (chloasma gravidarum)Therefore, it is advisable to use sunscreen daily.
In terms of digestion, it is possible to notice heartburn, indigestion, and abdominal bloatingLeg cramps, especially at night, may also occur, related to venous compression and circulatory changes. Staying well-hydrated, moving frequently, and doing gentle stretches can help relieve these symptoms.
Checks you will have in week 12 of pregnancy
It's time to do the first important ultrasound From a medical point of view: the 12th week of pregnancy ultrasound. It is performed when the length of the embryo from head to rump (crown-rump length or CRL) is between 45 and 84 mm, which corresponds approximately to the interval between weeks 11 and 13 and a few days.
The exploration can be done via the abdomen or via the vaginaBoth methods are valid and safe. Abdominal ultrasound offers slightly lower resolution but allows for a better examination of the fetus's overall structure; vaginal ultrasound provides a more detailed image, although probe movement is more limited. Many specialists combine both methods depending on the specific assessment required in each case.
In this ultrasound, the specialist will measure the baby to confirm the gestational age and adjust the gestational age and expected delivery date If necessary. The date calculated from the last menstrual period does not always coincide with the actual development of the fetus, and the crown-rump length measurement allows for correction with a margin of error of less than one week. The number of babiesSometimes the surprise is significant when we're told: there are two! In multiple pregnancies, it's also assessed whether the fetuses share a placenta or amniotic sac, a key piece of information for planning follow-up.
In addition, a first review of the fetal anatomyThe ultrasound checks for the presence of all four limbs, the correct position of internal organs (stomach, bladder, heart), the spine, the skull, and bone ossification, as well as the absence of organs outside the body. Although the most comprehensive morphology scan is performed around week 20, some serious malformations can be detected at this stage.
One of the most important aspects of this ultrasound is the screening for chromosomal abnormalitiesThe sonographer will measure the nuchal fold or nuchal translucencyThis is a small accumulation of fluid at the back of the fetus's neck. When this measurement is higher than expected for gestational age, it increases the risk of Down syndrome or other genetic disorders, so the case will need to be studied in more detail. Other markers are also assessed, such as... presence of the nasal bone, the flow in the ductus venosus or the functioning of the tricuspid valve cardiac.
On this date, the well-known triple screening or combined first trimester screeningWe will have a blood sample taken to determine the levels of two proteins produced by the placenta (PAPP-A and free beta-hCG). This data, combined with the nuchal translucency measurement, other fetal measurements, and maternal age, allows us to calculate the statistical risk that the baby will have Down syndrome, Edwards syndrome, or other chromosomal abnormalitiesIt is important to remember that this is a screening test, not diagnostic testIt offers a risk calculation, but does not absolutely confirm or rule out the presence of an alteration.
As an alternative or complement, it is also possible to carry out the fetal DNA detection test in maternal blooda non-invasive test with a very high reliability for some common trisomies. If combined screening or fetal DNA testing indicates a high risk, the specialist may recommend invasive diagnostic tests, such as the chorionic biopsy and amniocentesis, which allow direct study of the fetus' chromosomes.
This week's ultrasound also assesses the uterus and maternal ovariesTo rule out the presence of fibroids, cysts, or other abnormalities, the placenta, umbilical cord, and the amount of amniotic fluid are examined. In many centers, this appointment is also used to perform the preeclampsia screening, measuring the flow of the uterine arteries using Doppler and, together with other clinical data, estimating the risk of developing hypertension in the second half of pregnancy.
Although the baby's sex can sometimes be seen in this ultrasound, Few specialists venture to confirm it categorically.because the margin of error remains high except in very favorable positions. It is usual to wait for the second-trimester ultrasound for more reliable confirmation.
You will likely have an appointment with your obstetrician to discuss all the results, answer any questions, and review your symptoms. It is also important to attend the first trimester maternal education talksIf you haven't already, you can take the following classes, which are usually given by the midwife at the Health Center. These classes cover care, warning signs, and healthy habits.
And from now on, with the main organs formed and a first major check-up completed, the second trimester begins, a stage in which many women They enjoy pregnancy more Thanks to the decrease in discomfort and the increase in energy, while the baby bump begins to show and the ultrasounds allow us to see more and more clearly that baby that grows day by day.
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