The First Nine Months By Vicki Dihle

Physician Assistant- Certified

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20 weeks after fertilization

For centuries, humans have marveled at the miracle of life. Until recently, the process that propels two microscopic

cells to unite and develop into a human being was a mystery known only to the Creator Himself. Now, thanks

to recent advancements in medical science and imaging technology, we have the privilege to directly observe the

developing life within the mother's womb. This technology allows us to witness the miraculous process that follows

the uniting of two cells. Barring the unexpected, this union will culminate in a fully formed human life — with inherent value and worth — in a mere 266 days.1 Witness the miracle in the making as we journey through the "First

Nine Months" of human life.

1The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003, pg 104

The First Nine Months

The time frames referenced below indicate gestational age. See page 9 for further explanation on the difference between fertilization age and gestation age.

Fertilization

The oocyte (also known as ovum) and sperm most often unite in the fallopian tube (uterine tube) to form a single cell called a zygote. The zygote contains 46 chromosomes, 23 chromosomes from each the oocyte and the sperm cell. This tiny new cell, smaller than a grain of salt, contains all the genetic information for every detail of the new 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. This new life is now known as an embryo.

~ 2.5 Weeks

The embryonic cells are continuously dividing while traveling down the fallopian tube before arriving to their final destination – the uterus – around 3 to 4 days after fertilization. Meanwhile, the lining of the uterus (endometrium) is preparing for implantation.

~ 3 Weeks The embryo begins to implant in the lining of the uterus. Once this occurs, a series of hormonal signals are triggered which prepares the uterus and the body to sustain the pregnancy, and prevent a monthly period (shedding of the lining of the uterus). The embryo is about 0.1 mm (about the size of the period used in this sentence) and the embryonic cells are beginning to differentiate into specific tissues and organs systems.2

~ 4 Weeks Implantation is typically completed around the 14th day after fertilization and is visible by ultrasound.3 There is enough of the pregnancy specific hormone (called human chorionic gonadotrophin - hCG) circulating in the mother’s blood to give a positive pregnancy test.4

~ 5 Weeks The foundation for every organ system is already established and beginning to develop. The first signs of brain development are evident. During this week, the foundation for the ribs, vertebra, and muscles are present, and the developing lungs are evident.5 The heart, about the size of a poppy seed6, is the first organ to function and begin beating; this can be seen by ultrasound.7

~ 6 Weeks At this stage the origin of the entire central nervous system (brain and spinal cord) is in place.8 Eye formation, jaws, and upper limb buds are evident. By the end of the 6th week, the lower limb buds are apparent.9

2 ibid, pg 2, 3, 29. 45 3 ibid, pg 47, 51 4 ibid, pg 44 5 Essentials of Human Embryology, Larsen, William, Churchill Livingston © 1998, pg 90 6 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 15 7 Essentials of Human Embryology, Larsen, William, Churchill Livingston © 1998, pg 67, 70, 73 8 “Understanding How the Brain Develops”, Maureen Mulligan LaRossa, R.N., Sheena L. Carter, Ph.D., www.pediatrics.emory.edu/NEONATOLOGY/DPC/brain.htm

~ 7 Weeks

The embryo makes its own blood in the liver, bone marrow, and spleen. The upper limbs are paddle shaped and the lower limbs are flipper like.10

~ 8 Weeks

The elbows and fingers become evident. Some reports show that the developing baby has spontaneous movement of the trunk and limbs. The vertebrae in the neck are able to bend, and the trunk is able to straighten. Further, some reports demonstrate that the embryo can respond by reflex to touch.11 The embryo is about ½” long.12

~ 9 Weeks There is rapid development of the limbs and fingers, and the soft boney tissues of the upper limbs begin to calcify and harden. Development of the intestines is quite prominent as well. The developing ears and nose are visible and there is pigment in the retina.13

9 weeks

~ 10 Weeks The upper and lower portions of the arms and legs are clearly distinguishable. The bony tissues of the lower limbs begin to calcify. The fingers and toes are lengthening and are separate digits. For the first time in development, the limbs purposefully move. By the end of the 10th week, the embryo has very distinct features and weighs about 1/3 of one ounce.14 There are 20 tiny tooth buds present in the gums.15 The eyelids are developing and begin to close. This marks the end of the embryonic stage of development.16

9 The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003, pg 84 10 ibid, pg 70, 84, 85 11 ibid, pg 85-86 12 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 18 13 The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003 pg 88 14 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 22 15 ibid, pg 23 16 The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003 pg 90-94

10 weeks ~ 11 Weeks

The developing baby has all major organ systems and is now known as a fetus, which is Latin for “young one” or “offspring.” At this stage of development, the fetus is about two inches long. During the next stages of development, the baby’s body will grow rapidly, and the tissues and organ systems will continue to mature and differentiate. The eyelids are fully formed and closed to protect the developing eyes, and they will remain closed until later in gestation. 17 The fetus is able to yawn and suck.18

~ 14 Weeks

The baby is able to urinate and swallow.19 Roughly three inches in length, the fetal body is rapidly growing while the head’s growth has slowed. The foundations for the fingernails and toenails are clearly distinguishable.20 The baby is coordinated enough to isolate the thumb and suck it.21

14 weeks

17 ibid, pg 102-103 18 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 24 19 The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003 pg 106 20 ibid, pg 103 21 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 37

14 weeks

~ 16 Weeks At approximately 4” in length and weighing nearly 3 ounces,22 the fetus can coordinate the movement of the upper and lower limbs which are easily visible with ultrasound though the mother will not likely feel them. Slow eye movements are noted for the first time. The gender of the fetus is recognizable on ultrasound.23

~ 18 Weeks

The skeleton of the fetus is hardening and calcifying and is visible by ultrasound. The external ear can be clearly seen on the outside of the head.24

~16 weeks ~22 weeks

~ 20 Weeks

The baby’s movement, known as quickening, can usually be felt by the mother, and the fetal skin has a protective covering known as vernix caseosa. If the fetus is female, her uterus is formed and her ovaries have eggs.25

22 ibid, pg 40 23 The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003, pg 106 24 ibid, pg 103, 106 25 ibid, pg 103, 107

~ 22 Weeks At this stage, the pregnancy is about half over, and the mother is beginning “to show.” The fully formed eyelids remain closed and hair is visible on the head and body. The fetus is about 7.5 inches long. If the fetus is male, his testicles are fully formed and are beginning to descend from the abdomen to the scrotum.26 The sensation of pain can be experienced by the fetus, possibly as early as 18 weeks. In fact, from now until about 32 weeks pain is felt more intensely than any other time in development.27

22 weeks

~ 24 Weeks The baby now weighs slightly more than one pound. Though survival is not guaranteed, a baby born at this stage of development has been known to survive outside the uterus. The baby inhales amniotic fluid in preparation for breathing. Hearing is well established and the baby can hear its mother’s voice and heartbeat.28 The baby’s skin is pink, translucent, and wrinkled. Additionally, rapid eye movements are present, and the fetus can have a blink-startle response resulting from sound applied to the mother’s abdomen.29

26 ibid, pg 102, 103, 107 27 Dr. Kanwaljeet S. Anand, M.B.B.S., D. Phil. Dr. Anand was asked by the U.S. Department of Justice to prepare a statement as an expert witness on fetal pain and the effects of maternal anesthesia on fetal pain, and to assist the Court in the assessment of the Partial-Birth Abortion Ban Act of 2003. Dr. Anand’s expert witness statement is dated January 15, 2004. 28 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 60, 61 29 The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003, pg 103, 107

~22 weeks

~ 28 Weeks The baby is now about 11 inches long and weighs about 2.5 pounds. With the support of intensive care, a fetus born at this stage is capable of breathing, and the brain is developed enough to coordinate rhythmic breathing and regulate body temperature. The wrinkled fetal skin begins to smooth because of increased fat. The spleen is primarily responsible for making fetal blood. The eyelashes are clearly evident, and the baby begins opening its eyes.30 The baby is able to respond to touch and sound, and also has fully functioning taste buds on the tongue.31

~ 34 Weeks

The baby, now about 19 ½” from head to toe and weighing about 5 pounds,32 continues to grow and mature. By this stage of development, the eyes are wide open and if a light were shined 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.33 The baby has active sleep and wake cycles.

~ 40 Weeks The baby is now roughly 20 inches long, has a more plump body and a firm grasp. The chest is more prominent.34 Typically, the baby is head down in the mother’s pelvis and is awaiting birth.

30 ibid, pg 103, 107 31 Watch Me Grow, Stuart Campbell, M.D., St. Martin’s Press©, 2004, pg 71, 72 32 ibid, pg 92 33The Developing Human, Clinically Oriented Embryology 7th Edition, Moore, Keith L., Saunders Publishing, © 2003 , pg 103, 107 34 ibid, pg 103

Newborn at 3 days old

For Further Information

Fertilization age refers to the time elapsed since conception: the fertilization of the egg by the sperm. Most women ovulate (release a mature egg from the ovary) in the middle of their monthly cycle. For instance, if a woman has a 28 day cycle, she will typically ovulate on the 14th day after her period began. If a woman conceives and becomes pregnant at that time, this becomes the first fertilization day. Gestation age is slightly different than fertilization age. Gestation age refers to the time elapsed since the mother’s first day of her last period. Typically, this is two or more weeks earlier than the fertilization age. In other words, if a woman had her period two weeks ago and then conceives, the gestation age of the developing baby is two weeks; fertilization age is one day. Gestation age is the one commonly used by medical professionals when referring to the age of the baby.