From the moment of conception, a woman’s body begins the incredible journey of growing new life. Over the course of nine months, a fertilized egg develops into a fully-formed baby, complete with all the necessary organs and body systems. Here is a week-by-week breakdown of what happens during fetal development in the womb.
Table of Contents
Week 1-4: Conception and Implantation
The first week of fetal development is actually the week of conception, when sperm meets egg and fertilization occurs. The fertilized egg then travels down the fallopian tube and into the uterus where it implants into the lining of the uterine wall.
During the first four weeks, the fertilized egg undergoes rapid cell division and begins to form the basic structures of the embryo, such as the neural tube, which will eventually become the brain and spinal cord.
Week 5-8: Organs Begin to Form
By week five, the embryo has officially become a fetus. The heart begins to beat and major organs, such as the liver and kidneys, start to form. Tiny limb buds appear and the face begins to take shape with the development of eyes, ears, and a nose.
During weeks six through eight, the fetus continues to grow rapidly and its features become more defined. The fingers and toes separate and the genitalia begins to differentiate.
Week 9-12: The Fetus Becomes Active
During weeks nine through twelve, the fetus becomes more active, moving its limbs and even sucking its thumb. The digestive system and urinary system begin to function, and the fetus is now able to excrete waste into the amniotic fluid.
The face becomes more human-like and the ears move to their final position on the sides of the head. The fetus can now hear the mother’s heartbeat and voice.
Week 13-16: Rapid Growth and Development
During weeks thirteen through sixteen, the fetus undergoes a period of rapid growth and development. The bones begin to harden and the baby begins to grow hair, including eyebrows and eyelashes.
The baby’s sex is now visible on ultrasound, and the mother may begin to feel movement, known as “quickening.” The fetus also begins to develop a sleep-wake cycle.
Week 17-20: Senses Develop
During weeks seventeen through twenty, the fetus’s senses begin to develop. The eyes can sense light and the baby may begin to blink. The taste buds are formed and the fetus can now taste the amniotic fluid.
The baby’s skin becomes less translucent and more opaque. The mother may now be able to feel more distinct movements from the baby as it continues to grow and develop.
Week 21-24: Lung Development and Viability
During weeks twenty-one through twenty-four, the fetus’s lungs begin to develop surfactant, which is necessary for breathing outside of the womb. If born prematurely, a baby born during this time may have a chance of survival with medical intervention.
The baby begins to develop more fat, which helps regulate body temperature, and the brain continues to develop rapidly. The baby is now about the size of a grapefruit.
Week 25-28: Brain Development and Sleep Patterns
During weeks twenty-five through twenty-eight, the fetus’s brain continues to develop rapidly, with the formation of new neural connections. The baby also begins to develop regular sleep patterns.
The baby’s eyes are now fully formed and begin to open and close. The baby can now also differentiate between light and dark.
Week 29-32: Growing Rapidly
During weeks twenty-nine through thirty-two, the fetus grows rapidly, gaining weight and length. The baby’s skin becomes less wrinkled as it accumulates more fat.
The baby’s movements may become more restricted as it grows larger in the limited space of the womb. The baby’s immune system begins to develop, and it may begin to develop its own unique set of fingerprints.
Week 33-36: Almost Fully Developed
During weeks thirty-three through thirty-six, the fetus is almost fully developed and is preparing for birth. The baby continues to gain weight and the lungs are now fully developed and ready to breathe air.
The baby’s movements may decrease as it settles into the head-down position in preparation for birth. The baby is now about the size of a small watermelon.
Week 37-40: Full-Term and Ready to Meet the World
During weeks thirty-seven through forty, the baby is considered full-term and ready to meet the world. The baby continues to gain weight and prepare for birth by moving into position in the pelvis.
The mother may experience “false labor” as the uterus begins to prepare for contractions, and the baby’s head may engage in the pelvis. The baby is now about the size of a small pumpkin.
Conclusion
The incredible journey of fetal development is truly amazing. Over the course of nine months, a tiny fertilized egg transforms into a fully-formed baby, ready to be born into the world. Each week brings new changes and developments, and every baby is unique in their own way.
Frequently Asked Questions
What is fetal development?
Fetal development is the process by which a fertilized egg grows and develops into a fully-formed baby in the womb over the course of nine months.
How does fetal development happen?
Fetal development happens through a series of stages, with each week bringing new changes and developments. The process begins with conception and ends with birth.
What are the stages of fetal development?
The stages of fetal development include conception and implantation, embryonic development, fetal development, and finally birth.
What factors can affect fetal development?
Factors that can affect fetal development include genetics, nutrition, exposure to toxins, and maternal health conditions such as diabetes or hypertension.
How can I ensure a healthy pregnancy and fetal development?
You can ensure a healthy pregnancy and fetal development by eating a well-balanced diet, getting regular exercise, avoiding harmful substances such as tobacco and alcohol, and