The journey of pregnancy is an incredible experience. From the moment of conception to the birth of a baby, it’s amazing to see how a little life is formed and developed. But, how does a baby develop inside the womb? In this article, we’ll take a closer look at the different stages of fetal development and learn what happens during each week of pregnancy.
Table of Contents
Week 1 – 4: Conception and Implantation
The first two weeks of pregnancy happen before you even know you’re pregnant. During this time, your body is preparing for ovulation. When an egg is released from the ovary and meets sperm, it’s fertilized and forms a single cell called a zygote. This zygote then travels down the fallopian tube and into the uterus where it implants itself into the uterine lining. This is the beginning of pregnancy.
During these first few weeks, the zygote divides and forms a ball of cells called a blastocyst. The blastocyst contains an inner cell mass that will eventually become the baby and an outer layer of cells that will form the placenta. By the end of week four, the blastocyst has implanted itself deeply into the uterine wall, and the baby’s heart begins to beat.
Week 5 – 8: Embryonic Period
The embryonic period is a critical time for development. During this time, the baby’s major organs and body systems begin to form. By the end of the fifth week, the embryo is about the size of a grain of rice. The head, arms, and legs begin to form, and the neural tube (which will become the brain and spinal cord) starts to develop.
By week six, the baby’s eyes and ears begin to form, and the heart is fully developed. The baby is now about the size of a pea. By week seven, the baby’s hands and feet begin to form, and the fingers and toes start to separate. The baby is now about the size of a blueberry. By week eight, the baby is about the size of a kidney bean, and all major organs are formed.
Week 9 – 12: Fetal Period
The fetal period is a time of rapid growth and development. During this time, the baby’s body begins to look more like a baby, and the organs and tissues continue to mature. By week nine, the baby is about the size of a grape, and the face begins to take shape. The baby’s eyelids close to protect the developing eyes, and the external genitalia begin to form.
By week ten, the baby is about the size of a kumquat, and the baby can move its limbs. By week eleven, the baby is about the size of a lime, and the baby’s teeth begin to form. By week twelve, the baby is about the size of a plum, and the baby’s digestive system begins to function. The baby can also suck its thumb.
Week 13 – 16: Second Trimester
The second trimester is often called the “honeymoon phase” of pregnancy. During this time, the baby’s growth and development continue, and the mother may start to feel the baby’s movements. By week thirteen, the baby is about the size of a peach, and the baby’s fingerprints are forming.
By week fourteen, the baby is about the size of a lemon, and the baby can make facial expressions. By week fifteen, the baby is about the size of an apple, and the baby can sense light. By week sixteen, the baby is about the size of an avocado, and the baby’s skin begins to thicken.
Week 17 – 20: Fetal Movement
During the second trimester, the baby becomes more active, and the mother may start to feel the baby’s movements. By week seventeen, the baby is about the size of a pear, and the baby can hear sounds outside the womb. By week eighteen, the baby is about the size of a bell pepper, and the baby’s hair begins to grow.
By week nineteen, the baby is about the size of a large heirloom tomato, and the baby can taste what the mother eats. By week twenty, the baby is about the size of a banana, and the baby’s eyebrows and eyelashes begin to grow.
Week 21 – 24: Viable Pregnancy
During weeks twenty-one to twenty-four, the baby’s lungs and other organs continue to mature. This is also the time when the baby becomes viable, meaning that it has a chance of surviving outside the womb with medical intervention. By week twenty-one, the baby is about the size of a carrot, and the baby’s bone marrow begins to produce red blood cells.
By week twenty-two, the baby is about the size of a papaya, and the baby’s senses continue to develop. By week twenty-three, the baby is about the size of an ear of corn, and the baby’s skin becomes more opaque. By week twenty-four, the baby is about the size of an eggplant, and the baby’s lungs begin to produce surfactant, a substance that helps the baby breathe outside the womb.
Week 25 – 28: Third Trimester
During the third trimester, the baby continues to grow and mature. By week twenty-five, the baby is about the size of a rutabaga, and the baby’s brain continues to develop. By week twenty-six, the baby is about the size of a head of lettuce, and the baby’s eyes begin to open and close.
By week twenty-seven, the baby is about the size of a cauliflower, and the baby’s immune system begins to develop. By week twenty-eight, the baby is about the size of an eggplant, and the baby’s lungs continue to mature.
Week 29 – 40: Final Stretch
During the final weeks of pregnancy, the baby continues to grow and prepare for birth. By week twenty-nine, the baby is about the size of a butternut squash, and the baby’s movements may become more restricted due to its growing size. By week thirty, the baby is about the size of a large cabbage, and the baby’s bones begin to harden.
By week thirty-one, the baby is about the size of a coconut, and the baby’s brain continues to develop. By week thirty-two, the baby is about the size of a jicama, and the baby’s skin becomes smoother. By week thirty-three, the baby is about the size of a pineapple, and the baby’s head begins to move down into the pelvis.
By week thirty-four, the baby is about the size of a cantaloupe, and the baby’s lungs continue to mature. By week thirty-five, the baby is about the size of a honeydew melon, and the baby’s growth begins to slow down. By week thirty-six, the baby is about the size of a papaya, and the baby’s head may engage in the pelvis.
During the final month of pregnancy, the baby continues to gain weight and prepare for birth. By week thirty-seven, the baby is considered full-term, and the baby is about the size of a winter melon. By week thirty-eight, the baby is about the size of a leek, and the baby’s movements may become less frequent due to its growing size. By week thirty-nine, the baby is about the size of a watermelon, and the baby’s head may be engaged in the pelvis.
By week forty, the baby is considered overdue, and the baby is about the size of a small pumpkin. At this point, the mother may begin to experience signs of labor, and the baby may be born at any time.
Frequently Asked Questions
Q: How long does it take for a baby to develop?
A: A baby takes about 40 weeks to develop from conception to birth.
Q: What happens during the first trimester?
A: During the first trimester, the baby’s major organs and body systems begin to form.
Q: When does the baby become viable?
A: The baby becomes viable around weeks 21 to 24, meaning that it has a chance of surviving outside the womb with medical intervention.
Q: How big is a full-term baby?
A: A full-term baby is about the size of a winter melon.
Q: When is a baby considered overdue?
A: A baby is considered overdue at week forty.
In conclusion, the process of how a baby develops inside the womb is nothing short of miraculous. From a single cell to a fully formed human being, it’s amazing to see how it all comes together. Each week of pregnancy brings new changes and developments, and it’s a joy to watch it all unfold. By understanding the stages of fetal development, we can appreciate the wonder of life and the incredible journey of pregnancy.