Your Baby's Development

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Now that you are pregnant a process has started inside of you that has repeated itself through the ages, but this doesn’t mean it’s any less complex. From two cells, your egg and your partner’s sperm, a new human being is going to develop: your baby.

Your Baby's Development During Your Pregnancy

Now that you are pregnant a process has started inside of you that has repeated itself through the ages, but this doesn’t mean it’s any less complex. From two cells, your egg and your partner’s sperm, a new human being is going to develop: your baby.

So that the complex process of the creation of a new being takes place, a set of biological circumstances have to take place, among them, an increase in the levels of certain hormones in pregnancy that may have certain side effects like nausea or other discomforts. But along with this discomfort you are going to experience new unforgettable experiences, especially if this is your first pregnancy. Feeling your baby move for the first time, noticing how your belly reacts when you speak to it is something very unique and special.

Every week you will be able to follow the changes and growth your baby undergoes from the day of conception until the moment he is ready to be born. You will know when he can listen to the sounds that come from the outside, when his brows have formed or if he is already sucking its little thumb

Welcome to this wonderful process of the creation of life inside of you.


  • At some time during this week a very special event has taken place inside your body: your egg and your partner’s sperm have met in one of your fallopian tubes, and fertilization has occurred.
  • Just a few days ago, your ovule and your partner’s sperm met and fused together to conceive your baby. Your baby is still very, very tiny. In fact, it’s still not considered a baby but an embryo. Its size is barely the size of the tip of a pencil.
  • Although you won’t be able to hear it yet with any device, at some time this week the baby’s heart will start beating, and will continue to do so throughout its life.
  • Your baby is starting little by little to look like a human being. Right up to now she looked more like a bean. It only measures a ¼ of an inch, or six millimeters, but its heart keeps pumping blood hard.
  • The extremities like the arms and legs have developed enough for your baby to even have elbows already. In a few weeks when, when her joints are developed she will love to bend them and move them around.
  • Now that he already has arms and legs, the cartilage and bones of his limbs and body are developing. His fingers and toes are more shaped, although they are still short and have yet to reach their full development.
  • Most of her joints and limbs are now developed, which means that the little one has started to move around bending and extending her arms and legs. In fact, she loves to move and if you have a chance to see your baby in an ultrasound around this time, you’ll see she doesn’t stop moving.
  • This is an important week because your baby is going from being an embryo to being officially a fetus. It’s a medical term which means the most critical part of the development of the baby has almost come to an end.
  • This week the placenta will probably start to function and will provide the baby with nutrients as well as removing waste products. The amniotic fluid that surrounds the baby is increasing which means that the kidneys are going to start to function.
  • Although the gender of the baby was determined from the moment of conception, it’s now when the genitals are taking shape. The intestines are settling further into the abdomen and the pancreas, a very important organ, is already producing insulin.
  • If you haven’t heard it yet, this week you will be able to clearly hear your baby’s heartbeat. From this week on the placenta will be the one in charge of providing the baby with all the nutrients she needs to grow.
  • The development of the sexual organs continues. In females the ovaries are settling in the pelvis while males are developing the prostate gland. Along with the sexual organs, there is another vital organ which has just developed and has started to function at this time: the thyroid gland.
  • Your baby’s limbs keep growing and finally her body is larger than her head. This, added to the fact that your baby is moving more often, may enable you to start feeling her movements during these weeks...
  • Your baby’s gender is already apparent, although he or she must be in the appropriate position in order for the technician or doctor performing the ultrasound to actually see it. Not only can the sex be determined, but you will be able to see the baby sucking her thumb...
  • Your baby keeps swallowing amniotic fluid where waste cells are found. This material accumulates in your baby’s bowels forming what is called meconium, which will be the first feces of the baby and are very dark in color.
  • Your baby’s digestive system continues functioning, storing the meconium you will see in the first diaper it soils. Aside from this, the main organs keep fine-tuning their functions and you will be able to see her internal structures clearly...
  • Your baby keeps moving nonstop, but now he has grown so much that, it's very likely his limbs will brush against the walls of your uterus. For this reason, these weeks are the ones in which you will feel the baby’s first movements.
  • The sensory cells responsible for the different senses; taste, touch and smell are developing in your baby’s brain. Her sense of hearing is already developed and she’s likely to get scared if very loud outside noises reach her.
  • The rapid growth your baby experienced in the previous weeks is slowing down a bit. On one hand your baby is now fine-tuning the functions of each and every organ and on the other hand storing fat.
  • Your baby’s brain is developing fast, an amazingly fast growth that will continue up to the first couple of years of its life. Another extremely important organ is the liver, which is now processing a substance called bilirubin. It’s a job the liver still does with a little of your help.
  • Your baby now looks like a newborn although thinner because she still doesn’t have enough fat stored under its skin to give it the plumpness she will have at birth. The eyes are already where they will be at birth and her eyelids are formed...
  • The fat your baby is storing is filling out his body proportionally, making him look more like the newborn you’ll have in your arms in a few weeks.
  • In a very short time your baby’s lungs will have blood vessels, a very important step in her development. In addition, the bone structure of the spine is already forming to house the bone marrow.
  • By the end of this week your baby’s lungs will have developed alveoli, tiny, capillary-rich sacs in the lungs where the exchange of oxygen and carbon dioxide takes place. Your baby’s nostrils will even be open, although he still would need help breathing if he were to be born preterm.
  • The baby’s lungs are now secreting a gaseous substance called surfactant, a substance which will help her air sacs inflate as she exits your body. Your baby continues to practice breathing movements.
  • Although some fat is being stored under your baby’s skin, she is plumper mainly due to the growth of the muscle tissues and bones. You will probably feel your baby’s kicking more intensely as weeks go by. This is because your baby has more muscle tissue.
  • More and more your baby looks like a newborn. The skin, which until now was wrinkled, is starting to smooth out due to the fat he is storing and muscle tissue build-up. Both the nails on his hands and toes are completely formed and keep growing.
  • Your baby keeps moving in your belly although she still hasn’t positioned herself upside down, as she will in the coming weeks. Her head keeps growing to adapt to her fast growing brain and now she spends much of its time opening and closing her eyes.
  • Your baby’s hands are now coordinated and can grab the umbilical cord easily. Most of his internal organs are fully developed, with the exception of his lungs. If a preterm labor were suspected or had to be induced for any reason, they would probably administer surfactant...
  • Your baby doesn’t have much room left in the uterus to move freely, so you might feel her movements differently now. Nevertheless, if you experience any change that you might consider abnormal, you must contact your doctor immediately.
  • Starting this week your baby may position himself upside down, in the birth position, but it’s also possible he will change position several times. You will notice that your baby is in a different position because you may feel his kicking more strongly around the rib area.
  • During these weeks a very important process is taking place for your baby’s health after birth: the transfer of the antibodies you have in your blood for the illnesses you suffered in the past, to the baby’s blood.
  • Your baby’s body is accumulating fat fast, especially on her arms and legs and is acquiring that chubby look newborns have on their limbs. Due to the lack of space in the uterus, her arms and legs are flexed most of the time and if she stretches them out even slightly, you will feel it.
  • Your baby’s lungs are the only organ that continues developing at this point. All the other organs are ready to start functioning and assume the bodily functions of your baby once the umbilical cord is cut.
  • If your baby were to be born right now she would be considered mature, or that she has reached its full development. Your baby keeps breathing amniotic fluid to practice the breathing motion, which will enable her lungs to finish maturing if she isn’t ready to be born yet.
  • In these final weeks your baby’s growth has slowed down, at least in length, although numerous neurons and brain connections continue developing. His lungs keep producing surfactant so they can expand when the baby takes his first breath once he is born.
  • The production of surfactant is increasing this week, getting ready for birth. The vernix, the waxy coating that protected her skin from the amniotic fluid during gestation is starting to disappear, although there will still be some remaining at birth.
  • The amount of amniotic fluid is starting to decrease in preparation for birth and the functions of the placenta are also decreasing. Nevertheless, your baby might not be ready to be born and it may still have a few weeks more left of gestation to do, depending on when you first got pregnant, in which case these functions will still go on.
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