It is a momentous experience in a woman´s life. For approximately nine months, the female body becomes a home for the formation and development of the fetus until it is ready for birth. A period which both the woman´s body and baby undergo significant changes and transformations.

We explore how it develops month by month and what changes manifest themselves on a physical level, in order to accommodate and offer the baby everything that it needs at all times.


• First Month: the magic moment

The beginning the pregnancy is marked by conception, whether naturally or by embryo transfer if reproductive techniques are used. At this early stage, the embryo is only a group of cells, but its DNA already contains everything it needs for its development. Approximately eight days after ovulation, the embryo Will be implanted in the uterus and begin to release the hCG hormone, which is used to detect pregnancy.

Due to this hormone, many women may start to experience some mild symptoms, such as fatigue, modo swings or even light bleeding, which can be confused with the onset of menstruation.


Second Month: formation of crucial organs

As the second month begins, gastrulation takes place: the cells of the embryonic disc give rise to three different layers (ectoderm, mesoderm and endoderm) that form the primitive organs. The baby experiences rapid growth and development. The central nervous system, eyes, ears and organs such as the heart (which is already starting to beat), kidneys, the brain, lungs and digestive system all are formed. Although still small, the embryo becomes a fetus and is already moving, although the mother does not feel it.

The mother may notice symptoms such as nausea, vomiting, breast tenderness, increased frequency of urination and changes in appetite. Sometimes, there are no apparent symptoms, which does not indicate any type of complication. Externally, there are no noticeable changes.


• Third Month: taking shape and defined features

This is the beginning of the fetal period, when the baby grows up to seven or eight centimeters. This month marks a crucial moment in the development. The central nervous system develops quickly and the fetus begins to show reflexes. Facial features begin to become defined. The organs continue to form. Fingers and toes separate and their nails begin to be formed.

The mother may see a decrease in symptoms from the first few weeks, however for some women, nausea may continue.


• Fourth Month: accelerated growth and “kicking”

The fetus undergoes a quick and significant growth period. It is covered with lanugo, a fine hair on the skin that allows it to conserve body heat. The size of the fetus becomes more evident and the mother may start to feel the first movements, something which is a very exciting moment. Even though the eyes remain closed, the shape of the face is now defined and a neck is formed. Fingerprints emerge and the fetus reaches 18cms long and weights about 100g.


• Fifth Month: the senses awaken

During this period, the senses of the baby are active and sharpened. The ears are developed enough so noise can be heard from the outside world, including the mothers voice. The cardiac chambers (atria and ventricles) are delimited and the heart beats strongly.

The mother can sometimes feel more energetic during this month and experience changes in her hair and nails. Moreover, it is possible that some dark patches may appear in the skin, due to the increase of melanin production.

It is possible that, when the mother is lying down, the fetus will move more, because when standing up, the fetus fits into the pelvis. This is why movement is limited when standing up. The navel may flatten or begin to protrude. In any case, it will return to its normal appearance after delivery.


• Sixth Month: Response to external stimulations

The fetus continues to grow, reaching a rough size between 25 and 35cms, even weighing up to 750g. Its activity also increases. The fetal movements become stronger and respond to external stimulations, for example light and sound. Eyebrows, hair and eye lashes begin to form. And the skin changes colour. It begins to experiment with gestures, opening and closing the eyes or sticking out the tongue. Body proportions tend to even out, so that the size of the head no longer stands out as much.

The pregnant belly is large now. Because of this, the mother may experience symptoms such as swelling of the feet and ankles, tiredness, increase of blood pressure and problems sleeping due to being uncomfortable.


• Seventh Month: maturing of organs and weight increase

The start of the last trimester. The baby continues to accumulate grease under the skin, which helps to control the body temperature. The skeleton begins to solidify too. Its internal organs continue to mature and its immune system is strengthened.

The mother may notice an increase in weight, resulting in more intense movements of the fetus. The space within the uterus begins to be more limited and there is an increase of urinating and shortness of breath, due to the pressure exerted by the expanding uterus.


• Eight Month: preparation for birth

The baby is almost completely formed and continues to gain weight: It will reach almost 50% of the desired weight needed for birth. Although it is practical formed, the lungs are still not mature. During this period, it moves itself into the birthing position, normally with the head down.

The mothers body begins to prepare itself for the birth. It may experience more discomfort, due to the increase of size of the uterus. Digestion can become more difficult, slower and heavier. It is possible that she experiences contractions known as Braxton Hicks: sensations of tensing and relaxing of the uterus which helps prepare the body for the birth. Tiredness increases, not only because of the weight of the baby and the size of the belly, but also due to difficulties resting and sleeping.


• Ninth Month: the final wait

In the final month of pregnancy, the baby’s formation is completed and ready for birth. It can measure up to 50cms and weigh 2.5kgs.

The baby places itself into the mother’s pelvis. Its skin is softer now, thanks to the increase of grease and the lanugo has now disappeared. It now moves less due to the increase of size and weight. However, the mother should not pass 1 day without feeling its movement, which will feel rougher, like kicking, now that the baby has little space around it.

The body of the woman prepares itself even more ready for the birth, and contractions can happen more often and become more regular. If after 42 weeks the baby still has not been born, the normal process is for a doctor to induce the birth, as there may be a risk if the baby stays in the mother´s womb longer than necessary.