A day after having been fertilized, the ovule divides for the first time. The division keeps occurring and at the 5th day, the cells start to form two groups. The external group of cells will form the placenta, while the inner ring of cells will form your baby. Right at the end of the first week, the fertilized ovule descends to the uterus, where it will stay for the oncoming nine months.
Most moms don´t know yet they are pregnant, although some may start noticing the first symptoms of pregnancy, such as fatigue and morning nausea.
After the second week, the embryo starts to develop. It has a big head, a stem, and a sort of tale. The eyes and ears begin a first facet of development. Additionally, a neural tube starts to form. The organ that will feed the baby starts to shape, the placenta. The volume of blood of the mother increases up to a 50%, to tailor the growing need for oxygen.
By the 4th week, the embryo has the size of a small bean. It grows about a millimeter a day, and different layers of tissue can be identified. Two small black dots can be seen, the future eyes of the baby. Small bulges that will later constitute the legs and arms appear on the embryo. So long, the tiny fast-beating heart has only one chamber.
Although it barely has the size of a lentil, the embryo starts to acquire a more defined shape. The head is big, the neck can be identified, and the arms and legs still don´t protrude much. During the 6th week, the growing process is very fast. Intestines, lungs, and muscle tissue start to appear.
All of a sudden, your baby already has eyelids and upper lip while nose and ears are about to start developing. Future legs and arms can be easily recognized. The heart and the liver are already functioning, and the skeleton, which is yet a soft cartilage, can be seen through the translucent skin.
Officially, your future baby is no longer considered an embryo but a fetus by the second month, and it is when the placenta begins feeding your child to be. Start paying attention to everything you ingest now!
What characterizes this stage, is the fast growth of the neurons: about 250.000 new nerve cells per minute! With about 4 cm in length and weighing about 5.5 grams, you baby´s nails start to grow, as well as the external sexual organs. But don´t expect an echo to detect the gender of your baby yet!
Although not fully developed, all main body systems and organs are already formed. Vocal cords appear, and kidneys start to function. At this point, your baby weighs about 14 grams and is 6 centimeters long.
Finally, the body of your child begins to be larger than the head. At this stage, the brain starts to control the baby´s movements. Furthermore, even when you may still don´t notice, the baby starts to move legs and arms. Right now, babies can even start holding their hands or feet, and begin to perceive the light. Gaunt hair starts growing in the head. Now your baby can reach 80 grams weight.
Congratulations! You are already in the middle of your pregnancy. From now on, your baby´s weight will augment over ten times, reaching about 3 kilograms weight, and will double the height from 25 to average 50 centimeters. It is now when the baby starts hearing, although the amniotic fluid distorts the sounds. Now your baby moves, swallows, urinates, Over 20 centimeters long, and weighing about 250 grams, your baby still has to grow a lot. However, even being this small, the baby already shows the shape and proportions of a newborn.
It is now when the baby starts developing the senses, specially touch, and taste. A greasy protective substance called vernix covers the skin of the baby providing protection against the amniotic fluid. The baby´s limbic system is in development, and it will be the responsible for controlling the future feelings of your baby. And, in the following weeks, the baby will experience mood changes! The baby is now 20 cm long and weights 340 grams.
You will be now feeling more movements. Your baby will be sleeping most of the day, but when awake he will have more energy and be more alert on what happens around. He will extend his arm and legs as a protective mechanism when hearing sudden intense sounds. Important reflexes such as suctioning begin to show up and your baby will, for instance, start suctioning his fingers. The baby´s weight should be around 1 kilogram now.
Some fatty tissue starts growing under the baby´s skins. The senses are now much more awake, and the cerebral cortex allows some knowledge: you baby begins now to recognize your voice!
The amount of vernix over the skin is to increase. I will help the baby regulate body temperature. With 1.5 kgs and about 43 centimeters, most of the babies start seeking the definitive position with the head facing down.
By now, the lungs should be fully developed or quite close to that. Therefore, most premature babies born at the 32 don´t need any breathing support.
Your baby´s nails reach the fingertips now! With 2 kilograms weight, the brain development of your baby is now believed to be pretty much like that of a newborn. Furthermore, scientists now believe that at 32nd-week babies can start creating their first memories.
The baby´s brain is growing very fast. All five senses are working now. Your baby can see the liquid world around, taste the amniotic fluid that feeds him, feel his finger when suctioning it, and hear the heart and voice of the mother. Your baby is now already 37 centimeters long and weighs over 2 kilograms.
Brain connections are expanding rapidly, and the baby perceives more and more stimulus, being very attentive to everything around! The baby is around 50 centimeters long, and weighs 2 kilograms!
You won´t feel as many movements as before; your baby simply has no much room. Your child is already 50 centimeters long or more!
Yes, your baby is about to fit entirely, with the head on the cervix, getting ready to be born.
Now you are on the countdown! Stay alert! You may still be two weeks to go, but only 5% of the babies are born on due date!
Your child is ready to be born! (If he already didn´t). Most of the vernix (that greasy substance covering the skin) has disappeared, although some of it may still be there in the skin folds. Depending on many factors, genetic inheritance playing a significant role, your baby may be between 48 and 53 centimeters, and the weight between 3 and 4.5 kilograms.
What if you reached 41 weeks?
Don´t worry, this happens to many women, and it can be due to many reasons: wrong due date calculations, having already had previous pregnancies of over 40 weeks or environmental factors. If you go through the week 41, and your baby still seems reluctant to come out, your gynecologist will most likely induce birth.