PREGNANCY
Week by week

PREGNANCY
Week by week

What is gestational age?

Gestational age is the term traditionally used by healthcare professionals to date pregnancy and refers to how long it’s been since the first day of your last menstrual period (LMP). The gestational age begins two or more weeks before the fertilization of the egg by the sperm.

Week by week:

2 Weeks | Conception Day

The egg and sperm most often unite in the fallopian tube (tube from the ovary to the uterus) to form a single cell called a zygote. This tiny new cell, smaller than a grain of salt, contains all the genetic information for every detail of the newly created life—the color of the hair and eyes, the intricate fine lines of the fingerprint, the physical appearance, the gender, the height and the skin tone.

Days 2–5

This new life is now called an embryo, and his or her cells continuously divide while traveling down the fallopian tube before arriving at the uterus, around days 3 to 4. Meanwhile, the lining of the uterus prepares to receive this new life.

3 Weeks | 1 Week

The embryo begins to implant in the lining of the uterus on about day 6. Once this occurs, hormones trigger the mother’s body to nurture the pregnancy and prevent her monthly periods. A blood test can show that the mother is pregnant. Around day 8, the baby is about the size of the period used in this sentence.

4 Weeks | 2 Weeks

A pregnancy test taken at this point can measure hCG, the pregnancy hormone in the mother’s urine, and tell her if she is pregnant. By now, the embryo is completely attached to the lining of the uterus and at this stage, nourishment comes from the mother.

5 Weeks | 3 Weeks

The heart, about the size of a poppy seed, is the first organ to function. The first signs of brain development are evident, and the foundation for every organ system is already established and beginning to develop.

The heart begins to beat just 21 days after fertilization,or 5 weeks after the mother’s last menstrual period began.

6 Weeks

Just 4 weeks after fertilization, the baby is growing rapidly and measures 1⁄8 of an inch long. The basic structure for the entire central nervous system (brain and spinal cord) has formed. The eyes are developing, and the arm and leg buds are now visible. The beating heart can be seen on an ultrasound scan—it’s already beating about 100-120 times a minute!

7 Weeks

The baby is now 1⁄3 of an inch long and is making its own blood. Depending on the baby’s gender, the testicles or ovaries are beginning to form. Tooth buds for baby teeth are taking shape in the jaw.

8 Weeks

The baby is now about 1⁄2 of an inch long. The elbows and fingers can be seen. Some reports show that the embryo can move its trunk and limbs. Lungs begin to develop. Taste buds are forming on the tongue, and eyelids are beginning to form.

At 8 weeks, the embryo can respond to touch by reflex.

9 Weeks

The baby measures 3⁄4 of an inch long and weighs almost 1⁄8 of an ounce. The developing ears and nose are visible, and there is pigment in the retina. The limbs and fingers are growing rapidly, and the bones in the arms are beginning to calcify and harden.

10 Weeks

The baby’s brain is growing rapidly. Each minute it produces almost 250,000 new neurons! The upper and lower portions of the arms and legs are clearly seen, as well as the fingers and toes. By now the external ear is fully developed. A baby boy begins to produce the male hormone, testosterone.

11 Weeks

Because the baby has all of the major organ systems and is a distinctly recognizable human being, he or she is no longer called an embryo, but is now known as a fetus, a Latin word for “young one.” The baby is about 2 inches long and can yawn and suck. The eyelids are fully formed and closed to protect the developing eyes. During the next several weeks, his or her body will grow rapidly, increasing in weight 30 times and tripling in length! The baby will make first movements, but the baby is too small for you to feel them.

14 Weeks

Now 31⁄2 inches long, the “young one” baby is coordinated enough to find his or her thumb and suck it. Fingernails and toenails are beginning to grow. The baby is also able to swallow and urinate.

16 Weeks

The heart beats between 110 and 180 times per minute and pumps about 26 gallons of blood each day. If she is a girl, millions of eggs are now forming in her ovaries. At almost 5 inches in length and weighing nearly 4 ounces, the baby can coordinate the movement of its arms and legs.

The gender of the baby might be seen on ultrasound at 16 weeks.

18 Weeks

In just 2 weeks, the fetus has almost doubled its weight to 7 ounces. The skeleton is hardening and calcifying and is visible on ultrasound. Reflexes such as blinking and frowning are now developed. The baby has its own unique fingerprints and toe prints.

 

By 18 weeks, fetal movement—commonly known as “quickening”—can usually be felt by the mother.

20 Weeks

The fetus is now about 10 inches long from head to heel and weighs 11 ounces. The baby has unique waking and sleeping patterns and even has a favorite position to sleep in. The pregnancy is about half over. Studies indicate that babies can feel pain at 20 weeks, and possibly even earlier. From now until about 32 weeks, the baby feels pain more intensely than perhaps a child or an adult might.

22 Weeks

Hair is visible on his or her head and body. The baby is about 11 inches long and weighs about 1 pound. If the baby is male, his testicles are beginning to descend from the abdomen to the scrotum.

At 23 weeks, rapid eye movements begin, and activity associated with dreaming.

24 Weeks

The baby now weighs approximately 1 1⁄2 pounds and inhales amniotic fluid in preparation for breathing. The ear has developed to the point where the baby recognizes his or her mother’s voice, breathing and heartbeat.

26 Weeks

Now the baby weighs almost 2 pounds, and he or she can react to sounds outside the mother’s body. Eyes can now respond to light, and the permanent teeth buds are apparent in the gums. Eyelashes and eyebrows are well-formed, and the hair on the baby’s head is growing longer.

28 Weeks

The baby is now approximately 15 inches long and weighs about 2 1⁄2 pounds. With the support of intensive care, a baby born at this stage is capable of breathing air. The brain is developed enough to coordinate rhythmic breathing and regulate body temperature. As the baby continues to gain weight, the skin becomes less wrinkled and more smooth.

34 Weeks

The baby is now about 17 inches long, weighs 41⁄2 pounds and continues to grow and mature. By this stage of development, the eyes are wide open, and if a light were shone into them, the pupils would constrict. The head is covered in hair, the fingernails have reached the tips of the fingers, and the toenails are close behind. The lungs are still developing, at this stage.

40 Weeks

The baby is now around 20 inches long and may weigh 7 to 8 pounds. He or she has a plump body and a firm grasp. Typically, the baby is head-down in the mother’s pelvis and awaiting birth.

Be patient—only 4% of babies are born on their due date!

Your journey

It’s normal to have questions and concerns about your pregnancy. At Hope Resource Center, we are here to help. Call 865-525-4673 to schedule your free appointment today.

sources

Moore and Persaud. The Developing Human: Clinically Oriented Embryology, 7th Edition.

Elsevier Health Services, 2000. Pennsylvania: Saunders, © 2001

Larson, William J. Essentials of Human Embryology. Elsevier Health Services, 1997. New York: Churchill Livingston, 1998

Tallack, Peter. In The Womb. Washington, D.C: National Geographic 2006

Campbell, Stuart M.D. Watch Me Grow! St. Martin’s Press, 2004

Mayo Foundation for Medical Education and Research. “Fetal development: What
happens during the first (second, third) trimester?”

LaRossa, Maureen Mulligan, R.N., and Sheena L. Carter, Ph.D. “Understanding How the
Brain Develops.”

Anand, Kanwaljeet, M.B.B.S,. D. Phil. “Expert Report of Kanwaljeet S. Anand, M.B.B.S. D. Phil.” Expert testimony before the U.S. Department of Justice describing the capacity of the fetus to feel pain.

Call 865-525-4673 to request a cost-free appointment at Hope Resource Center today.