Fetal Development Week By Week Guide

Pregnancy starts from the moment the egg is fertilized. This is from where the counting begins. The women may not be pregnant at this point. The total pregnancy time is 40 weeks.

Week 1:


The first day of pregnancy is decided by the first day of a woman’s last period.


Week 2:


Around 350 million sperms which had been ejaculated enter the vagina into the uterus and the fallopian tube to fertilize the egg. Sperms can survive in this environment for 5 days. The egg starts floating in the uterus after being fertilized. Fertilization takes place in this week.


Week 3:


In the 3rd week of pregnancy a new life begins. When the egg reaches the uterus, implantation process begins wherein the egg burrows itself in the lining of the uterus.


Week 4:


Implantation of the egg into the uterus takes place in this stage. The embryo is about a one hundredth of an inch long at this time.


Week 5:

The embryonic stage begins during the 5th week. At this stage the embryo begins to grow in size from a tiny speck to about 2 mm.




Week 6:


At 6 weeks the heart begins to beat. The embryo has reached a size of about 8 mm. New blood vessels and cells are forming at this stage. The spinal cord begins to close.


Week 7:


In this stage the arms and legs begin to grow. The embryo at this stage is about ½ inch in length. Baby’s eyes and ears begin to develop. The development of the stomach and intestine takes place and the digestive system overall becomes more refined.


Week 8:


During this stage the embryo starts to practice moving. Arm and leg buds appear. The face begins to take shape. At this stage the embryo is about ¾ inch in length.


Week 9:


Fingers and toes form at this stage. The main construction of the heart is completely. Upper lip as well as the nose tip formation is seen. Eyelid formation is seen.


Week 10:

The embryo is now a fetus at this stage. The feet at this stage are about 2 mm. The neck begins to take shape. The body muscles are almost developed. The ear and nose can now be seen clearly.


Week 11:


At this week, the neurons multiply. The baby at this stage can stick out its tongue and swallow. The cartilage starts calcifying to bone.


Week 12:


The fetus starts moving and the face starts looking like a baby’s face. Finger nails and toenails appear. The fetus is almost half an inch long.


Week 13:


At this stage the baby flexes and kicks and grows to about 3 inches in length. The nose and chin are well defined. The child can open and close his mouth and begins to learn to suck his thumb.


Week 14:


In this stage the hormones start to develop. The kidneys are producing urine and the eyes are moving slowly to the centre of the face.


Week 15:


The bones and the muscles grow during this stage of pregnancy.


Week 16:


Facial expressions are possible during the 16th week. The fetus measure about 5 inches now.


Week 17:


Fat accumulation takes place. The umbilical cord grows thicker and stronger.


Week 18:


The baby begins to hear. The fetus measures about 15cms. The baby can be startled by loud noises.


Week 19:


The genitals at this stage are recognizable. The features of a baby’s heart are visible during an ultrasound.


Week 20:


The mother will probably start feeling the fetus moving at this stage. The hair growth on the body has started. The baby at this stage starts weighing about 310 grams.


Week 21:


The overall nourishment evolves during this stage.


Week 22:


The taste buds start to develop. The fetus starts to respond to loud sounds. The baby starts to develop a regular sleep pattern.


Week 23:


A sense of balance develops. The bones in the middle ear harden. Eyebrows are visible. Baby weighs about a pound.


Week 24:


The baby practices to breadth at this stage. If the baby is born at this time, he will be able to survive.


Week 25:


The brain starts to grow rapidly. Hands as well as the sexual organs are fully developed.


Week 26:


The baby measures to about 14 inches long, weighs around 760 grams. The baby’s eyes begin to open at this time. Hands are very active.


Week 27:


The baby’s hearing continues to develop. Eyes can blink, open and close. The baby weighs around 2 pounds.


Week 28:


The baby begins to recognize the mother’s voice and develops his sleeping pattern. Milk teeth develop under the gums. Eyes start to move in its socket.


Week 29:


Movement of the baby is rapid at this stage. Baby’s muscles and lungs are developing. He can taste and respond to pain.


Week 30:


Baby weighs around 3 pounds. The wrinkled skin becomes smooth.


Week 31:


The eyes are completely open and he starts to respond to light and sound.


Week 32:

The baby weight about 4 pounds. The fat layer is getting thicker under the skin. The diameter of the baby’s head is almost 4 inches.


Week 33:


The baby drinks about a pint of the amniotic fluid per day. Half of the mother’s weight will directly go to the baby.


Week 34:


Rapid growth continues. The child has an excellent chance of surviving outside the womb.


Week 35:


Baby’s reflexes are coordinated during this period. 90% babies born at this stage survive.


Week 36:


Contractions of the womb can be felt. The baby may be dropped into the birth canal at this stage.


Week 37:


The water may break at any time during this stage. The baby weighs about 7 pounds. The diameter of the head is about 3.5 inches.


Week 38:


The development of the child is complete. The body fat continues to develop.


Week 39:


The baby will continue to kick and punch which will be felt in the lower pelvis. The head is about 4 inches now. Most babies are born with their heads out first.


Week 40:


The due date arrives. The contractions could begin at any moment. All the systems of the body are well developed.

Similar Posts:

GD Star Rating
GD Star Rating

Leave a Comment