In the second and third months, baby development has started to become evident rapidly. In this article, we will examine baby development week by week.

Baby development in the second and third months: 

In the second and third months, baby development has started to become evident rapidly. In this article, we will examine baby development week by week.

  • 5 – 6 weeks:  

Your baby is now the size of a tiny sesame seed. This living thing, up to a point in your blood, is called an embryo . It is located in the amniotic sac, surrounded by amniotic fluid. The amniotic fluid protects it from danger. Beta HCG level in pregnancy tests is around 1500-2400 mg/dl. The amniotic sac can be seen with transvaginal ultrasound. It grows 1-2 mm every day. The pregnancy cord (yolk sac) located close to the gestational sac is formed. Shopping continues.

In the embryo, the circulatory system begins to come into play. In its most primitive form, veins begin to form. Heartbeats may not yet be heard on ultrasound, but they begin to beat weakly.

The cells in the embryo line up in a row and the neural tube is formed. The neural tube is the structure that will form the brain and spinal cord. It is one of the most important parts of embryo development. Problems that occur in any part of this developmental stage cause a series of congenital anomalies called neural tube defects. It is one of the most common congenital anomalies.



The opening at five different points in the neural tube development process closes within weeks. Neural tube defects have problems closing these openings. Anomalies develop according to the region where the problem is experienced. If the closure problem is somewhere along the canal from the tail part of the neural tube, spina bifida may develop, and if it is in the head part, anencephaly may develop. Neural tube closure problems can mostly be due to folic acid deficiency, high fever, drugs or agents that harm the development of the fetus called teratogens.

As of this week, she has focused on doing the placenta task. The baby starts to grow well in the 6th week. exceeded 4 mm. On average, it is the size of a lentil. It continues to grow rapidly and triples at the end of the week.

The heartbeat is more regular and can go up to 150 beats per minute. The body is bent in a C shape. The buds from which the arms and legs will develop become evident. The nose, mouth and ear structure begins to take shape. Intestines are formed. Lungs are forming. The vertebrae are prominent in the back.

From the 6th week, the expectant mother begins to feel the pregnancy well. His belly is growing. Nausea, vomiting may occur. Pregnancy symptoms are seen due to hormonal changes.

  • Week 7 – 8:  

The length of the embryo has reached around 9-13 mm. At the end of the 8th week, it will exceed 20 mm. The uterus is the size of an orange. It starts to press on the surrounding tissues, and there may be complaints such as frequent urination. Pregnancy symptoms are starting to show themselves.

The head part is more prominent than the other parts. The brain and face are developing rapidly. Eyes and nostrils begin to appear. The auricle, liver and upper lip begin to form. The heart rate increases. It is around 120-160 beats/minute. If the heart rate drops below 85, there is a problem with the pregnancy. It should be well evaluated. At the end of the 8th week, your baby growing in the womb is now called a fetus .

  • Week 9: 

The fetus has reached 2-3 cm in length and 3 grams in weight. His feet and toes are now starting to emerge. Fingers and toes are developing with a web between them. The arms are slightly bent at the elbow.

Vital internal organs of the fetus have now begun to take shape. Pancreas, liver, spleen, thymus begin to work. A connection begins to be established between the brain and the nervous system. Although hand and arm movements are no longer felt by the expectant mother, they can be seen. The baby’s facial features begin to become clear. Nostrils, mouth, eyes, eyelids, earlobes are about to finish their development.



Although it still provides oxygen exchange from the mother through the placenta, the heart valves and chambers of the fetus are also developing. Since the nape of the fetus develops, it can hold its head a little higher and turn it.

  • Week 10:

The fetus is starting to look more like a human now. Bone and cartilage tissues begin to form. Knee and elbow bends are formed. The arms continue to grow. Vital organs such as brain, liver, intestine, kidney take their final shape. Digestion begins, urine is produced. The heart is fully developed. Fine hair growth has started on the scalp. Gums and jaw structure are formed. The size of the fetus is around 3-4 cm. On average it is the size of an apricot.

  • Week 11:

Although the gender of the baby cannot be determined by ultrasonography yet, it begins to become evident. Hair begins to form, tongue and palate are seated in the mouth. Ears begin to appear. Head structure is forming. The head is one-third of the whole body. He can close his hands open. The baby is mobile, its length is around 4 cm.

  • Week 12:

At the end of the 12th week, the first trimester of pregnancy is over and the risky period when organ development is intense is over. The baby reaches 4-7 cm in length and 15-20 grams in weight. Fingers and toes are separated from each other, sucking movements have started in the mouth. All internal organs are working, urine is produced, the baby swallows amniotic fluid. The baby is visible by ultrasonography, but the gender cannot be determined.

  • Week 13:

Your baby is now completing the first three months. After this week, as he has passed the risky parts of his developmental stages, he will have a stronger defense against the dangers from the outside. The belly of the expectant mother is growing and she feels her baby growing in her belly. Pregnancy-related complaints have decreased considerably.

This week, the baby’s fingerprint is formed. Gender is well defined, it can be seen with good observation in ultrasonography. The movements of the baby can also be monitored in ultrasonography. Previously, the imbalance in the body-to-head ratio begins to decrease gradually.