Pregnancy Week By Week

Development of the Baby

From Fertilization to Birth:


Day 1:  Fertilization: all human chromosomes are present;

A unique human life begins … a girl or a boy!

Day 6: Embryo begins implantation in the uterus.

Day 22: Heart begins to beat with the child’s own blood, often a different type than the mothers’.

Week 3: The child’s backbone, spinal column, and nervous system are forming. The liver, kidneys and intestines begin to take shape.

Week 4: By the end of week four the child is ten thousand times larger than the fertilized egg.

Week 5: Eyes, legs, and hands begin to develop.

Week 6: Brain waves are detectable, mouth and lips are present, fingernails are forming.

Week 7: Eyelids and toes form, the nose is distinct. The baby is kicking and swimming.

Week 8: Every organ is in place, bones begin to replace cartilage, and fingerprints begin to form. By the 8th week the baby can begin to hear.

Weeks 9 and 10: Teeth begin to form and fingernails develop.  The baby can turn his head, and frown. The baby can hiccup.

Weeks 10 and 11: The baby can “breathe” amniotic fluid and urinate.

Week 11: The baby can grasp objects placed in its hand; all organ systems are functioning. The baby has a skeletal structure, nerves, and circulation.

Week 12: The baby has all of the parts necessary to experience pain, including nerves, spinal cord, and thalamus. The vocal cords are complete. The baby can suck its thumb.

Week 14: At this age, the heart pumps several quarts of blood through the body every day.

Week 15: The baby has an adult’s taste buds.

Week 17: The  baby can have dream (REM) sleep.

Week 19: Babies can routinely be saved at 21 to 22 weeks after fertilization, and sometimes they can be saved even younger

Week 20: The baby recognizes its’ mothers voice.

Months 5 and 6: The baby practices breathing by inhaling amniotic fluid into its developing lungs. The baby will grasp at the umbilical cord when it feels it.  Most mothers feel an increase in movement, kicking, and hiccup from the baby. Oil and sweat glands are now functioning. The baby is now twelve inches long or more and weighs up to one and a half pounds.

Months 7 through 9: Eyes and teeth are present. The baby opens and closes his eyes. The baby is using four of the five senses (vision, hearing, taste, and touch.)  He knows the difference between waking and sleeping, and can relate to the moods of the mother. The baby’s skin begins to thicken, and a layer of fat is produced and stored beneath the skin. Antibodies are built up, and the baby’s heart begins to pump 300 gallons of blood per day. Approximately one week before the birth the baby stops growing, and “drops”, usually head down into the pelvic cavity.