The First 9 months
Ultrasound
You clothed me with skin and flesh,
and knit me together with bones and sinews.
You have granted me life and steadfast love,
and your care has preserved my spirit. (Job 10:11-12)
Introduction
The beginning of human life inside the womb is certainly humanity's oldest, and perhaps most marvelous, mystery. The Bible records what David prayed to God thousands of years ago: "For you formed my inward parts; you knitted me together in my mother's womb. I praise you, for I am fearfully and wonderfully made. Wonderful are your works; my soul knows it very well" (Psalm 139:13-14). Thanks to incredible advances in medical and imaging technology, we can understand and see more than ever before about the stages of the amazing process wherein babies are "wonderfully" knit together by God in their mothers' wombs!
However, we know firsthand that facing an unplanned pregnancy is scary, and carries with it many doubts and uncertainties. But we have also found, as we have sat with girl after girl, that the fear we all feel toward the unknown is worse in the end than learning the truth about what we fear most. And that's exactly what we hope you find as you browse the pages on our web site, the truth; for it is truth that supports our mission of saving lives and protecting futures.
Technically speaking, pregnancy is the period following conception during which a developing embryo, and later, a fetus, is carried within the uterus. Human pregnancies average 266 days (38 weeks) from conception to childbirth. Traditionally though, the length of a pregnancy is counted from the woman's last menstrual period (LMP), which adds about 2 weeks to the duration. Dating the pregnancy from the LMP is how we calculate the gestational age of the baby and thus how physicians determine an average pregnancy length of 40 weeks (280 days).
Pregnancies are broken up into three trimesters of about three months (or 13 and 1/3 weeks each).
What follows is a trek through some of the significant milestones to expect while you are expecting! We invite you to explore this glimpse into what is truly God's miracle of life!
(The meanings of many words or medical terms that may be unclear to you can be found in our glossary.)
The First Trimester 1
[Note: Except for the first few days of development, the "gestation age" (the one traditionally used by medical providers to date pregnancy) has been used. According to gestation age, the average human pregnancy lasts approximately 40 weeks or 280 days, making the trimesters just over 13 weeks each.]
Conception day - The egg and sperm most often unite in the fallopian tube (tube connecting the ovary to the uterus) to form a single celled life called a "zygote." The earliest stage of human life, the zygote is the conception of a new life separate from that of mother and father, and it contains all 46 chromosomes (23 from each parent carried by egg and sperm respectively) and with them all the genetic information (such as DNA) he or she will need for every detail of human life. Such genetic information includes the color of the hair and eyes, the gender of the baby, and the height and skin tone. This new human life is now called an embryo.
Days 2-5 (after conception) - The cells of the embryo continuously divide while traveling down the fallopian tube before arriving at the uterus, around days 3 to 4. During this time also the lining of the uterus prepares for the implantation of the human embryo.
Days 6-10 (after conception) - The embryo begins to implant in the lining of the uterus around day 6. Once this occurs, hormones trigger the mother's body to sustain the pregnancy and prevent her monthly periods.
Week 4 - At this point the embryo is completely attached to the lining of the uterus. There is now enough of the pregnancy-specific hormone (hCG) circulating in the mother's blood to give a positive pregnancy test.
Week 5 - By now the foundation for all of the baby's organs has already been established and is beginning to develop. The first signs of brain development are evident at this age also, and the ribs, vertebrae, and muscles begin to form. The developing lungs are evident, and the heart, about less than 1/16 inch in diameter (it would take around 900,000 hearts this size to equal a pound!), is the first organ to function. Though tiny, through ultrasound technology the baby's beating heart can be seen.
Week 6 - The origin of the entire central nervous system (brain and spinal cord) is laid out. Eyes form, and the jaws and budding arms now become visible. By the end of week 6, the budding legs can also be seen.
Week 7 - The embryo now makes his or her own blood in the liver, bone marrow, and spleen. The arms have a paddle-like shape to them while the legs resemble flippers.
Week 8 - The baby's elbows and fingers are visible now. The embryo has been seen making spontaneous movements of the trunk and limbs at this stage, and shows reflexive response to touch as well. The vertebrae in the neck can bend, and the trunk can straighten. All this in a baby about 1/2 inch in length!
Week 9 - The arms, legs, and fingers show rapid development while the soft bony tissues of the arms begin to calcify and harden. Also notable development of the intestines takes place. The ears and nose are distinct features on the face now and the eye's retina contains its pigment.
Week 10 - At this point the arms and legs are clearly developed and the bony tissue of the legs begins to harden. Both the fingers and the toes are lengthening and visible as separate digits. For the first time in this baby's life, he or she can voluntarily move his or her arms and legs. By the end of week 10, the embryo looks distinctly human while weighing only 1/3 of one ounce. In the mouth, the gums now contain 20 tiny tooth buds, and on the face, the developing eyelids begin to close.
Week 11 - Now that the growing baby has all the major organ systems intact and a distinct human appearance, it ceases to be called an embryo and assumes the name "fetus" (a borrowed Latin word meaning "offspring"). Still a miniature two inches long, the baby's body will begin a period of rapid growth moving into the second trimester accompanied by further maturation of the tissues and organ systems. The eyelids are fully formed and remain closed to protect the developing eyes. Finally, the baby can yawn and suck during this stage also.
The Second Trimester
Week 14 - The baby now can urinate and swallow. About three inches long, the baby's body continues to grow quickly while the growth of the head begins to slow. The beginnings of fingernails and toenails can be seen. The fetus possesses enough coordination and motor skill to find and suck his or her thumb.
Week 16 - Approximately four inches long, and weighing nearly three ounces, the baby can coordinate the movement of his or her arms and legs. However, due to the baby's still small size, the mother will not likely feel the baby's motions. Eye movement is also visible, and an ultrasound picture taken at this stage can reveal the gender of the baby.
Week 18 - The skeleton of the fetus is becoming increasingly hard and can be seen on ultrasound. Also, the external ear is clearly visible on the side of the head.
Week 20 - The mother can feel the baby move (sometimes known as "quickening"). If the baby is a girl, then her uterus is already formed and her ovaries contain eggs.
Week 22 - At just past the halfway point in the pregnancy, the mother begins "to show." The baby is now 7.5 inches in length. The eyelids, fully formed, remain closed while the head and body now show hair. If the fetus is male, his testicles are fully formed and are beginning to descend from the abdomen into the scrotum. The baby can now feel pain (maybe as early as 18 weeks). In fact, from now until around 32 weeks, pain is felt more intensely than any other time during the fetus' development.
Week 24 - Slightly over one pound in weight, babies born at this stage of growth have been known to survive, although there can be no guarantee. The fetus has begun inhaling amniotic fluid to prepare itself for breathing upon emerging from the womb. The baby's hearing has developed to the point that it can hear the mother's voice and heartbeat. The baby's skin is pink, translucent, and wrinkled. Rapid eye movements are noticeable, and he or she may become startled and blink if sound is applied to the mother's abdomen.
For behold, when the sound of your greeting came to my ears, the baby in my womb leaped for joy. (Luke 1:44)
The Third Trimester
Week 28 - Now almost a foot in length, the wrinkled fetal skin of this 2.5 pound baby begins to smooth as fat increases. The spleen assumes primary responsibility for producing fetal blood while the eyes are beginning to open, with eyelashes clearly visible. Not only is the baby completely able to respond to touch and sound, but also has fully functioning taste buds on the tongue. With the support of intensive care, a fetus delivered during this stage of development is able to breath air, and the brain is mature enough to coordinate rhythmic breathing and regulate body temperature.
Week 34 - Nearly 19 inches in length and weighing approximately five pounds, the baby continues to grow and develop. The eyes are wide open and the pupils would constrict if light were shone on them. The head of the fetus is covered with hair, and the fingernails have grown to the tips of the fingers with the toenails slightly trailing. The baby has developed active wake and sleep cycles during this stage as well.
Week 40 - Plump bodied and firm gripping, the baby is now about 20 inches in length. The chest of the baby has become more outstanding, with the breasts sticking out a bit. Most often, the baby's head is down in the mother's pelvis and awaiting birth.
Well there you have it - a glimpse into the truly amazing process of the growth of human life in the womb from conception to birth. The creation and development of life in a woman's body is nothing short of a creative miracle of God. We can now better understand David's intimate prayer to his Father and Maker:
For you formed my inward parts; you knitted me together in my mother's womb. I praise you, for I am fearfully and wonderfully made. Wonderful are your works; my soul knows it very well. (Psalm 139:13-14)
To contact one of our centers and speak with a member of our caring and concerned staff, click here. We would love to walk through the wonder of pregnancy with you while providing you with every help and support we can.
1 The following information has been adapted from "The First 9 Months" (Colorado Springs, CO 80995: Focus on the Family, © 1999, 2005; www.heartlink.org).