CC Students for Life

Lenoir, North Carolina

Fetal Development

First Trimester

Conception: A new life is created! The DNA in the 46 chromosomes of that small cell contain full instructions about this new person’s sex, eye color, shoe size, brain capacity and other physical traits. Every person’s life begins at conception – as a single, separate, living cell. After this point, nothing new is added except nutrition and oxygen.

Week One: At about the sixth day, the growing child attaches to the wall of the mother’s uterus. The uterus’ nutrient-rich lining welcomes the tiny tenant and soon the child is sending out the “all systems go” chemical signal that can be detected on a home pregnancy test.

Weeks 3 & 4: The baby’s heart is beating! The heart begins to beat as early as 18 days after conception and is beating strongly by 21 days. The baby’s development is rapid during this time. Between three and four weeks, the baby’s head and spinal column become easily distinguishable, and arm buds appear. Legs will begin to appear just days later. The umbilical cord forms, transporting the child oxygen and nutrients absorbed from the mother’s blood by the placenta.

Weeks 5 & 6: Already fingers are forming and the child’s mouth and lips are apparent! During this time, the baby begins to make his or her first movements. Blood courses through the little body – often a different blood type then the mother’s. At five weeks most of the baby's remaining organs have begun to development. At six weeks, the baby has brain waves that can be measured with an electroencephalogram.

Weeks 7 - 9: At seven weeks, the baby's ears, eyes and nose begin to appear, and teeth begin to form under the gums. At eight weeks cartilage and bones begin to form. TheIntestines start to move out of the umbilical cord and into the abdomen. During this time the baby swims freely in the womb with a natural swimmer’s stroke, although the mother does not begin to feel the baby’s movements until about 4½ months. As early as eight weeks, the baby begins to swallow the amniotic fluid. Some babies even begin hiccupping!Baby's length is 0.61 in. and weighs 0.04 of an ounce.

Weeks 10 & 11: The baby’s little feet are perfectly shaped. The baby also has eyelids, fingernails and fingerprints. The baby can even grasp an object placed in the hand! The kidneys are beginning to form urine and the baby begins to mimic breathing. All the baby’s body systems are in place and active. The baby has a skeletal structure, nerves and circulation. From this point on, there is only growth in the size and maturation of the organs already present.

Weeks 12 - 14: Vocal cords begin to form, eyes begin to move closer together and ears shift to their normal place on the side of the head. At 13 weeks your infant is about 2.91 inches and weighs around 0.81 ounces. At this point all nourishment is received from the placenta. At 14 weeks a boys' prostate gland develops girls' ovaries move from the abdomen to the pelvis. Lanugo (very fine hair) covers the baby's body and will continue to grow until 26 weeks gestational age.

Second Trimester

Weeks 15 & 16: The baby is now big enough that his or her movements can be felt by the mother. Hearing begins to develop as do fingernails and toenails. Eyebrows are also growing as is the hair on baby's head.At 16 weeks baby and placenta are roughly the same size. Fat begins to form under the baby's skin which increases insulation. Often times the heartbeat can be heard with an external monitor, and the baby's gender can sometimes be determined at this point. The baby also begin to breath in and out amniotic fluid to help his lungs to grow. (3.98 inches long and weighs 2.47 ounces).

Weeks 17 - 19: He or she has a much more normal "human" appearance now. At this age they are able to hold their heads more erect and their body and limbs are longer and in proportion to their head. The baby's skeleton is transforming from cartilage to bone. At 18 weeks vernix (a white cheese-like protective material) forms on baby's skin with the lanugo (soft, lightly pigmented hair covering the body and limbs); both serving to protect your baby's skin during the months in water. At 19 weeks Your baby has the same awake and sleep patterns of a newborn. (Measures 6.02 inches and weighs about 8.47 ounces).

Weeks 20 - 23: In the fifth and sixth months, the baby responds to a number of outside stimuli: music, sudden noises, and voices. The baby will especially respond to the sound of its mother’s voice. Babies at this age also respond to pats on the mother’s abdomen, and react with pleasure, excitement, anxiety or fear to various external and environmental stimuli. The baby could now survive outside the mother’s womb. Not long ago, the age of survival – or viability – was 30 weeks; then 25 weeks. Today it’s 23 weeks. From this point until birth the baby simply gains weight and strength. When the baby’s ready to meet the outside world he or she will arrive.

Weeks 24 - 26: Bring on the bulk! Baby gains about 6 ounces this week. The weight is in muscle, bone mass and organs. At 25 weeks the structures of the spine begin to form -- joints, ligaments and rings. Dexterity starts to improve. Your baby can make a fist and would clasp objects placed in palm. By week 26 retinas begin to form, and brain wave activity for hearing and sight begins to be detectable.

Weeks 27 & 28: Your little one's brain continues its rapid growth. Lungs continue to grow and prepare for functioning outside of the womb. At week 28 baby's eyes are completely formed now. Lungs are capable of breathing now (but baby would still struggle and require medical attention if born now).

Third Trimester

Weeks 29 & 30: The baby's head is now in proportion to the rest of it's body. The baby is becoming more sensitive to changes in light, sound, taste and smell. The brain is now able to regulate beginning stages of breathing and body temperature control. At 30 weeks the child starts to open and close it's eyelids and can move his eyes from side to side - even being able to follow a bright light. Bone marrow now takes over production of red bloods cells, and the baby even has the ability to produce tears.  Approx. length is 15.7in, approx weight is 2.9lbs.

Weeks 31 - 33: Lungs are the only major organ left to complete development. Remember, that while you may be anxious to meet your little one that these last few weeks can be vital - with each day increasing your baby's ability to breathe on her own. At 32 weeks all five senses are working. Your little one is fascinated and practicing testing these out as much as possible! By 33 weeks neurons and synapses are developing in huge numbers -- forming connections in your baby's brain will give him the skills he needs to thrive as a newborn. This week, he may be able to coordinate sucking and swallowing with breathing. (Growth - 17.2 inches and 4.23 pounds)

Weeks 34 & 35: Antibodies from your blood are being transferred to him. These immunities continue to build until birth. Then breast milk will add even more protection against disease. At 35 weeks baby's hearing is fully developed, so be sure to talk to your child. Your baby is now taking up most of the uterus and you may even feel like your chest has run out of room! (Growth - 18.2 inches 5.3 pounds)

Weeks 36 - 38: If he hasn't already, this week your baby may drop into the birth canal. Baby has a fully developed pair of kidneys and her liver has begun processing some waste products. Your baby continues to practice breathing movements. Isn't it amazing how she can breathe "under water?" At 38 weeks your child's intestines are accumulating lots of meconium. Meconium takes on the role of being your baby's first bowel movement -- removing the waste that has accumulated.

Weeks 39 & 40: His lungs are maturing and surfactant production is increasing and fully prepared to take on the outside world! 15% of your child's body is fat. Since he hasn't learned to shiver yet, these fat stores will help regulate his temperature. Congratulations! Any day now you will be cradling your son or daughter! Cherish the moments and learn all you can about this new personality in your life. They go by all too fast!


Fetal development information taken from A Baby’s First Months published by National Right to Life Education Trust Fund.