The approximate duration of pregnancy is 280 days of gestation, or what is the same 38 weeks from the moment of fertilization of the ovule and 40 weeks from the date of the last menstruation (FUM).
Next, we will take a fascinating tour of the gestation of the human being week by week, from the moment of conception until the day of birth. You will be able to know how your baby grows and the changes that occur in the mother's body throughout pregnancy.
Week 1 of pregnancy
Week 1 of pregnancy you're not really pregnant yet, since during that week you will have the rule.
Vaginal bleeding is caused by the desquamation of the functional layer of the endometrium that has been prepared to house the fertilized egg. Since there is no fertilized egg, menstruation occurs.
It is the preoccupational stage, variable from one woman to another, that begins with the first day of the period.
Week 2 of pregnancy
In week 2 of pregnancy your body prepares for ovulation that will occur, depending on each woman, this week or later. The egg that will be fertilized by a sperm will be released giving rise to a new life.
Fertile days are the days when you are more likely to get pregnant. The woman's cycles usually cover 28 or 30 days, so the central days of the cycle will be the most conducive to getting pregnant: 14 or 15 days after the first day of menstruation.
Week 3 of pregnancy
In week 3 of pregnancy occurs the magic moment of fertilization. It's really when you get pregnant.
The first sperm that reaches the ovum penetrates the external barrier until it enters its nucleus and achieves the fertilization that 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.
Week 4 of pregnancy
In week 4 of pregnancy, four to seven days after fertilization, embryo implantation occurs on the walls of the mother's womb, where it will continue to develop until the day of her birth.
On some occasions, when the embryo is implanted in the uterus, the endometrial tissue erodes causing slight bleeding that, when coinciding with the time when the period should be lowered, can be confused with menstruation. This bleeding is known as implantation bleeding.
Week 5 of pregnancy
If you have not yet felt the first symptoms of pregnancy, you are likely to begin to notice them now in week 5 of pregnancy, along with the absence of the period. Swelling and hypersensitivity of the breasts, nausea, desire to urinate frequently, tiredness and drowsiness ... are some of the signs that you are pregnant.
Menstruation has not arrived, with a week of delay (in regular cycles) it is time to take the pregnancy test if you have not done so before.
In this week the embryo is barely three weeks old (corresponding to week 5 of pregnancy) and is about one millimeter wide and four-five millimeters long. It already begins to have more differentiated parts in its characteristic “C” shape: the upper and lower part, the left and right, the front and the rear are differentiated.
Week 6 of pregnancy
In week 6 of pregnancy the heart of the embryo starts beating regularly, although it is probably not yet detected on ultrasound.
Make spontaneous movements, but there are still many weeks to begin to notice them, because at this point we speak of a small embryo of a few millimeters: it is about a centimeter long.
Week 7 of pregnancy
In the 7th week of pregnancy the embryo measures around one centimeter long and weighs less than one gram. The buds or buds of arms, the plate of the hand and the lower limb in the form of a shovel are visible. The brain transforms into five areas and some cranial nerves are visible.
We are in the period of organogenesis, because from the different layers of the embryo the body's organs are forming. The exposure of the embryo to teratogens (agents that can induce or increase the possibility of congenital malformations) during these weeks (4 to 8), constitutes the most critical period of its development.
Week 8 of pregnancy
The embryo in the 8th week of pregnancy has an age of 6 weeks since fertilization occurred. The length from the crown to the buttocks is around 15-20 millimeters, and the weight is around three grams. And although it is so small, it is already extremely complex.
The external appearance of the embryo has been modified by the formation of the brain, liver, somites, limbs, ears and eyes. At this time we can say that It already has characteristics that give it a human appearance.
Week 9 of pregnancy
The embryo in week 9 of pregnancy continues to develop, change and grow. It is already the size of a grape, about two and a half centimeters. Very small yet for us to notice but for him, the growth is vertiginous. The tail at the end of the back disappears: our son is increasingly looking like a human being.
The embryo can already move even if it does so involuntarily. The development of your nervous system increases and sometimes, as I told you, the embryo is not there anymore, but it can be detected that it trembles. Your brain does not control these movements., but they are spasms that indicate that it is forming connections correctly.
Week 10 of pregnancy
In the 10th week of pregnancy there is a change in the way the baby is named. When the 10th week of pregnancy ends we stop using the word embryo to call it a fetus.
Now all its organs have formed and heart, brain, liver, kidneys and intestines are functioning. They will grow and develop continuously until birth but it is already possible to recognize them perfectly defined.
Week 11 of pregnancy
At 11 weeks of pregnancy the baby weighs approximately 8 grams and weighs between 4 and 6 centimeters.
His fingers are already separated, the membranes that united them have disappeared. Although your head is still half of your body it is completely normal at this time. The ears are migrating to their final position and the little one can now open and close his hands.
12 week of pregnancy
Ideally, the first ultrasound should be scheduled in the 12th week of pregnancy, although a previous one may have been performed to confirm the pregnancy.
Our baby, in the 12 week of pregnancy, is already the size of a kiwi. It will measure 6 centimeters and weigh about 14 grams, we could make a cot in the palm of your hand.
He does not stop moving, kicking and shaking his arms and head, already formed perfectly, it even seems as if he is pushing himself when he touches the walls of the uterus with his feet.
Week 13 of pregnancy
In the 13th week of pregnancy, your head is still disproportionate but each time we will see how the relative size is more balanced with respect to the rest of the body.
The baby's fingers are already perfectly separated, he has flexibility in his knees and elbows and he even gets to be able to suck his finger perfectly.
The intestines are already in the internal part of the body, inside the abdomen of the fetus and not inside the umbilical cord.
Week 14 of pregnancy
At 14 weeks pregnant It will weigh about 30 grams and will measure approximately 10 centimeters. It looks like a miniature baby.
His facial features are becoming increasingly evident and we could even see how he gestures with the muscles of his face, he sucks his finger and his little hand.
He drinks amniotic fluid and pees inside his belly, waves his arms and legs and seems to feel happy in his intrauterine life.
15 week of pregnancy
Starting this week, the skin, which is practically transparent, begins to cover the lanugo, a layer of very fine hair that we can see at birth and that, as you will have heard or have told you, is normal and then falls alone.
The eyes are approaching the position they will finally have and, although they are still closed, they begin to be sensitive to the changes of light that reach through the belly. The ears begin to have some of their characteristic folds.
Week 16 of pregnancy
In the week 16 It already measures between 10 and 11cm. The legs are already longer than the arms and some joints begin to differentiate, such as the knees, ankles, elbows and wrists.
It begins to open the fingers of the hands and also begins to close them in what appears to be the beginning of the grip reflex. Thanks to him he begins to take his feet, the umbilical cord, or his hands, one with the other. Nails also appear on hands and feet.
Week 17 of pregnancy
In the 17th week of pregnancy, when the baby has been training for 15 weeks, it measures about 11-13 cm and weighs about 100 grams.
It continues to grow and especially its legs, since the head now grows less. The fatty tissue layer begins to form under your skin, which will then serve to protect you from the cold. Your ear is more developed and can move abruptly if there are loud sounds outside.
18th week of pregnancy
In the 18th week of pregnancy it measures about 13-15 cm and weighs about 150 grams. His femur is now about 2.7 cm and the circumference of his head is about 15.4 cm.
The heart is maturing, being divided by the two atria and the two ventricles. The atria are still communicated with each other, passing blood from the right to the left through the so-called oval foramen, as a measure to prevent the passage of blood to the lungs. The moment the baby is born, when he has to start using them and starts breathing, that hole closes.
Week 19 of pregnancy
Your head, arms and legs already have a size provided with the rest of the body and has started to grow hair in the head. The ears and eyes are almost in their final position.
It's amazing, but if you're expecting a girl, her little ovaries that won't be bigger than a button already contain primitive eggs that will give rise to the ovules.
20th week of pregnancy
In the 20th week of pregnancy the baby measures 16 centimeters and about 350 grams.
His lungs begin to practice the exercise of breathing and his digestive system does the same by swallowing amniotic fluid. Your brain rapidly develops areas destined for the senses, and already has 30,000 million neurons.
Around the 20th week of pregnancy a high resolution ultrasound called morphological ultrasound, of great importance in prenatal control. The specialist in performing it thoroughly analyzes the baby's organs to detect possible malformations, although not with 100% reliability.
21 week of pregnancy
It already moves vigorously inside your gut making you notice with kicks, stretches and turns that it does inside the uterus, where it still has room to move comfortably.
It moves around 50 times per hour, but at the moment that you notice more its movements is when you lie down to rest, especially if you have eaten before, the baby is activated. During the day, when you are also on the move you cannot feel them so much.
Week 22 of pregnancy
In the 22nd week of pregnancy (20 weeks from conception) your baby It measures 27 centimeters and weighs almost 500 grams.
You can perceive your eyelids, nails and eyebrows, although the latter still have no color, they are white fluffs that are seen above the eyes.
Looking at it, it almost looks like a full-term baby, but you still need to gain weight. Your body fat represents 1% of your body, but from now on you will gain layers of fat, which will help you regulate your body temperature.
Week 23 of pregnancy
You may notice that your skin is a thin layer that covers your body, but it is no longer translucent, but begins to look reddish and wrinkled. The layers of fat will be deposited under the skin.
His eyes are completing his development, although its color is not yet the color with which it will be born because its iris is not pigmented. It will not even be the final color, because until about six months and even until the first year of life it may not be defined.
24 week of pregnancy
Your baby is about 30 cm in total (about 21-21 cm from the head to the culete) and weighs about 600-700 grams. It is increasingly likely to survive in the event of premature delivery as the lungs begin to produce the pulmonary surfactant that would allow it to breathe out of the uterus.
Your baby still has enough space inside the uterus and can move freely and change position often. Although he still sleeps about twenty hours a day, he has frequent short periods of activity in which he will do more and more articulated somersaults.
25th week of pregnancy
This week the baby is already 34cm in total, about 22 cm from the head to the ass, and weighs between 700 and 800 grams. His hair begins to be defined and has a certain color and texture, although these may still change when he is born.
Although your eye color is not fully defined, since it needs light for the pigments to finish forming, your baby already has eyelashes and can open and close the eyes. His ear continues to develop rapidly and he can perceive sounds from outside as well as those he produces when moving in your uterus.
Week 26 of pregnancy
As he still has space in the uterus to float and move, he is quite active and coordinates his movements better and better. On ultrasound you can see him "pedaling" with his legs and press the uterine wall with your feet. The cuffs also have more strength and can catch the cord.
Although it is not very common, maybe the kicks will hurt in the ribs, in that case it is best to change position, lying on your side.
27th week of pregnancy
The baby is quite thin yet, although from now on you will accumulate more fat and gain weight considerably. The length from the crown to the buttocks would be about 24 centimeters (about 36 centimeters in total), and the weight is close to reaching one kilogram.
From this week there are more chances that the baby will survive if born prematurely. But there are 13 weeks left until the end of pregnancy, so it continues to develop.
28th week of pregnancy
The fetus already measures about 26 centimeters from the crown to the buttocks (about 36 centimeters in total) and weighs about 1100 grams. He would already have chances of surviving in case of premature delivery, although his lungs that begin to work are not yet prepared to breathe air and the regulation of his body temperature would be deficient.
Brain growth during this month is spectacular, the fetus increasingly feels more stimuli from the inside and those that get dimmed from the outside.
Week 29 of pregnancy
Fat accumulation continues and the baby is large enough to determine its presentation, that is, its orientation in the uterus (buttock or cephalic). However, you will still have time to change this position during the next month.
The adrenal glands of the fetus produce androgenic substances that circulate in their blood and when they reach the placenta they become estrogen (estriol), to stimulate the production of prolactin in the mother's body (and that the breasts prepare to give breast to baby).
30th week of pregnancy
The bones are already developed, but they are still soft and flexible. To give them firmness, the baby begins to store iron, calcium and phosphorus.
You can already differentiate between sweet and savory flavors. Your respiratory system continues to mature, and in fact, your baby rehearses respiratory movements and has hiccups every day. But above all the biggest change we will find in the maturation of the baby's nervous system.
Week 31 of pregnancy
The lungs are practically formed, although they cannot still breathe outside the mother. Its skeleton is in full growth and its bones continue to store calcium, phosphorus and iron.
You can turn your head and "see", not only distinguish the light from the darkness and your kidneys are fully functional and eliminate more than half a liter of urine a day.
Week 32 of pregnancy
Your baby's brain is practically formed, so much so that many doctors do not see differences between the brain of a newborn and that of a 32-week-old. Its weight is around 1,900 grams and its height is about 42 centimeters and if it were born at the moment it would have an 85% chance of survival, but its lungs are not yet mature.
Week 33 of pregnancy
In this week it is possible that, if you have not already turned around to put yourself in a cephalic position, do it or start “thinking” about doing it. Now you can still, but in a few weeks your size will make it more difficult to turn.
It has been seen that fetuses of this age make some rapid eye movements (REM) They are like the ones we do when we dream. For this reason it is believed that 33-week-old fetuses already dream when they sleep. The question that surely we all ask ourselves is, and what do they dream of? Question that has no answer, obviously, because it is impossible to know.
Week 34 of pregnancy
The baby measures approximately 46 centimeters and weighs about 2,200 grams. Their lungs are almost completely formed and their bones have been hardening but they are still very flexible, including those in the head.
His skull is not yet completely closed, which allows him to adapt more easily to the birth canal at birth. Therefore, some babies are born with a cone-shaped or crushed head, but this is reversed within a few days of birth.
Week 35 of pregnancy
Already It measures about 46 cm from head to toe and the weight is about 2,500 grams. The skin begins to smooth, fat begins to settle and the lanugo begins to disappear.
Your kidneys are now fully developed and the liver is also starting to function. Most of his basic physical development is already complete. In the coming weeks it will be dedicated to gaining weight.
36th week of pregnancy
Your baby's skin is getting pinker due to the accumulation of fat and in most cases it will already be upside down and fitted. You are also losing the hair that covered you and the vernix caseosa which is a creamy, whitish substance that has covered your skin the entire time it has been inside you. All this will be swallowed and is what will form the meconium, which will be the first bowel movements of the baby (it is a very sticky black paste).
37th week of pregnancy
In the 37th week of pregnancy It measures about 46-48 cm and weighs about 2,900 grams. His femur is now about 7.2 cm and the circumference of his head is about 33 cm.
If everything has gone as planned, by now you will be in a cephalic position, that is, face down, ready to be born. Being already a trained baby, what happens inside the belly is an increase in height and weight to arrive in better conditions, in addition to continuing to receive immune cells from the mother. It is estimated that, in addition, increases about 15 grams of fat per day, which will serve to better regulate the temperature outside.
Week 38 of pregnancy
Your baby It measures approximately 50 centimeters and weighs about 3,200 kilos. His little hands can already grab, in fact he already does it with the umbilical cord that has been his toy inside the uterus.
His head is covered with hair and he looks like he will be born with. Some babies are born with a lot of hair while others are born almost bare, but it is something that can then be reversed. The hair with which it is born usually falls over the first months of life.
39th week of pregnancy
In the 39th week of pregnancy the baby's length is about 36 centimeters from the crown to the buttocks (about 52 centimeters in total) and the weight is around 3250-3300 grams.
Still receiving many nutrients from the mother, through the umbilical cord, which is approximately 1.3 centimeters thick. Antibodies also cross the placental barrier and strengthen the baby's immune system by the time it is born, and continues to accumulate fat.
40th week of pregnancy
You will finally meet your baby! What will it look like? When the baby is born, it has a bruised color, it may be pulling pinkish or yellow. The skin appears covered with waxy vernix, blood and lanugo remains ... High hormonal levels make your genitals appear swollen.
Maybe the head has something deformed by having crossed the birth canal, but it is normal and little by little the baby's head will take its final form.
Photos | iStockphoto, Raelene Gutierrez, pixydust8605, Footloosiety on Flickr CC
