Baby growth week by week during pregnancy

Growing the baby week by week in pregnancy

Pregnancy is a journey full of incredible changes, both for the mother and for the baby that is forming. Over the course of approximately 40 weeks, the mother's body becomes the perfect environment for a tiny human to develop from one cell to a full newborn. In this article we tell you, week by week, how your baby is growing inside the womb, based on reliable and up-to-date medical information.

Evolution of fetal development from conception to delivery

First trimester: from week 1 to 12

During the first trimester, the embryo goes through fundamental stages of formation. Although it is still very small, decisive processes such as implantation, the formation of major organs and the onset of heartbeats are already occurring.

"During the first 12 weeks, the risk of miscarriage is higher, but it's also when the foundations of the nervous system, heart, spine and other essential organs are established."

• Week 1-2: Technically, you're not pregnant yet. The body prepares for ovulation and possible fertilization.
• Week 3: Fertilization occurs and the zygote is formed.
• Week 4: The embryo implants in the uterus.
• Week 5-6: The neural tube begins to form and the heart begins to beat.
• Week 7-8: Arm and leg sprouts appear.
• Week 9-10: Developing facial features and internal organs are already recognized.
• Week 11-12: The baby is called a fetus and is about 5-6 cm long. It moves, although you don't notice it yet.

Second trimester: from week 13 to 27

In this trimester, the baby grows rapidly and many women begin to notice its movements. Its organs mature and the body begins to resemble that of a miniature newborn.

• Week 13-16: Fingerprints appear. The baby may suck his thumb.
• Week 17-20: The senses are developed. You begin to notice the first movements.
• Week 21-24: The skin is very thin, but it already has eyebrows and eyelashes. The respiratory system begins to prepare.
• Week 25-27: It can open its eyes and responds to external sounds. The body gains weight and fat.

From week 20, many mothers feel the baby's first movements

Third trimester: from week 28 to delivery

In the last trimester, the baby perfects its vital functions, gains weight and prepares for life outside the womb. The mother may also experience more intense physical changes due to the baby's growth and weight gain.

• Week 28-31: The brain develops rapidly. The baby dreams and responds to light.
• Week 32-35: Adopt a fetal position. Its bones are fully formed but soft.
• Week 36-38: The baby is fitted into the pelvis and is ready for delivery.
• Week 39-40: Full-term birth. The baby is about 50 cm tall and weighs between 3 and 4 kilos on average.

What factors influence the development of the baby?

Maternal nutrition, emotional state, rest, environment and genetics are key to the growth of the baby. In addition, following prenatal controls allows possible complications to be detected in time. According to the WHO, adequate antenatal care can significantly reduce the risk of complications for both mother and fetus.

What can I do week by week?

In addition to eating a healthy diet and going for your checkups, you can keep a pregnancy diary, talk to your baby, do gentle exercises recommended for pregnant women, and use helpful tools like calendars or pregnancy tracking apps.

If you wish, at MilkyNest you can find resources, guides and calculators to accompany you at each stage of pregnancy.