Pharmacist Grab Pharmacist Grab Bag QuestionBag Question

Carly GreenCarly Green

Can you explain how a fetus Can you explain how a fetus develops over the nine month develops over the nine month

pregnancy?pregnancy?

First TrimesterFirst Trimester

The first two weeks of pregnancy is actually before The first two weeks of pregnancy is actually before conception happens. The due date for a woman is conception happens. The due date for a woman is calculated by counting ahead 40 weeks from the start calculated by counting ahead 40 weeks from the start of her last period. Conception typically happens on two of her last period. Conception typically happens on two weeks after her last period starts.weeks after her last period starts.

Week three is when the woman actually becomes Week three is when the woman actually becomes pregnant. The sperm and egg join together to form a pregnant. The sperm and egg join together to form a zygote. It then travels down the fallopian tube towards zygote. It then travels down the fallopian tube towards the woman’s uterus. The zygote will begin rapidly the woman’s uterus. The zygote will begin rapidly dividing with the inner cells becoming the embryo.dividing with the inner cells becoming the embryo.

Week four is when the zygote which is now known as a Week four is when the zygote which is now known as a blastocyst reaches the woman’s uterus. It will burrow blastocyst reaches the woman’s uterus. It will burrow into the uterine wall for nourishment. During this week, into the uterine wall for nourishment. During this week, the placenta begins to form. A woman may receive a the placenta begins to form. A woman may receive a positive pregnancy test now.positive pregnancy test now.

First TrimesterFirst Trimester

Week five is when the Week five is when the baby’s brain, spinal baby’s brain, spinal cord, heart, and other cord, heart, and other organs form. The organs form. The embryo is now made of embryo is now made of three layers which are three layers which are the ectoderm, the ectoderm, mesoderm, and mesoderm, and endoderm. The baby’s endoderm. The baby’s heart and a primitive heart and a primitive circulatory system form circulatory system form in the mesoderm. The in the mesoderm. The baby’s heart is beating baby’s heart is beating at a steady rhythm. The at a steady rhythm. The baby’s skeleton is also baby’s skeleton is also beginning to form.beginning to form.

The baby is between 1/16 to 1/18 inch long which is about the size of the tip of a pen.

First TrimesterFirst Trimester

Week six is when the neural tube along the baby’s back closes Week six is when the neural tube along the baby’s back closes and the heart is pumping blood. Basic facial features appear and and the heart is pumping blood. Basic facial features appear and the body becomes C-shaped. The hand and feet buds have the body becomes C-shaped. The hand and feet buds have webbed-like structures. A vaginal ultrasound could detect an webbed-like structures. A vaginal ultrasound could detect an audible heartbeat now.audible heartbeat now.

Week seven the baby’s brain and face are developing rapidly. Week seven the baby’s brain and face are developing rapidly. Tiny nostrils become visible, and the eye lenses begin to form. Tiny nostrils become visible, and the eye lenses begin to form. The arm buds from week six are now in the shape of paddles. The arm buds from week six are now in the shape of paddles. The baby currently weighs less than an aspirin.The baby currently weighs less than an aspirin.

In week eight, the baby’s arms and legs have grown longer and In week eight, the baby’s arms and legs have grown longer and fingers and toes have formed but are still webbed. The upper lip fingers and toes have formed but are still webbed. The upper lip and nose have formed. The trunk of the body is straightening. The and nose have formed. The trunk of the body is straightening. The baby may begin to move, but it will not be felt by the mother. The baby may begin to move, but it will not be felt by the mother. The bones are beginning to form, and the muscles can contract.bones are beginning to form, and the muscles can contract.

First TrimesterFirst Trimester

In week nine, the baby’s arms grow, develop bones, and In week nine, the baby’s arms grow, develop bones, and bend at the elbows. Toes begin to form, and the baby’s bend at the elbows. Toes begin to form, and the baby’s eyelids and ears continuing developing. All the baby’s joints eyelids and ears continuing developing. All the baby’s joints are working and allowing the baby to move freely. The are working and allowing the baby to move freely. The heart has divided into four chambers, and the valves are heart has divided into four chambers, and the valves are beginning to develop. The baby is now the size of a grape.beginning to develop. The baby is now the size of a grape.

Week ten the baby’s head becomes Week ten the baby’s head becomes more round and the neck starts to more round and the neck starts to develop. The majority of their vital develop. The majority of their vital organs, kidneys, liver, brain, and lungs organs, kidneys, liver, brain, and lungs are functioning, but will continue to are functioning, but will continue to develop. The fingers are no longer develop. The fingers are no longer webbed. The baby is actively swallowing webbed. The baby is actively swallowing amniotic fluid and kicking his legs.amniotic fluid and kicking his legs.

First TrimesterFirst Trimester

Week eleven, both the fingers and the toes have Week eleven, both the fingers and the toes have separated by week 11. The baby’s skin is still very separated by week 11. The baby’s skin is still very transparent, but his bones are beginning to harden. transparent, but his bones are beginning to harden. The external genitalia have almost completely formed.The external genitalia have almost completely formed.

In week twelve, the baby will begin to take on more of a In week twelve, the baby will begin to take on more of a normal appearance as the eyes move closer together normal appearance as the eyes move closer together and the ears move closer to their final position. The and the ears move closer to their final position. The intestines have grown so fast that they actually extend intestines have grown so fast that they actually extend into the umbilical cord, but they will begin to move back into the umbilical cord, but they will begin to move back into the abdomen. The kidneys can now secrete urine, into the abdomen. The kidneys can now secrete urine, and the nervous system is continuing to mature. The and the nervous system is continuing to mature. The baby may have developed more complicated reflexes baby may have developed more complicated reflexes such as sucking.such as sucking.

First TrimesterFirst Trimester

In week thirteen, fingerprints In week thirteen, fingerprints are now located on the tips of are now located on the tips of the baby’s fingers. The kidney the baby’s fingers. The kidney and urinary tract are and urinary tract are completely functional which completely functional which allows the amniotic fluid he allows the amniotic fluid he has been swallowing to be has been swallowing to be excreted. Covering the baby’s excreted. Covering the baby’s skin is a fine, soft hair called skin is a fine, soft hair called lanugo. .

Second TrimesterSecond Trimester

In week fourteen, the baby’s arms are going to begin to lengthen In week fourteen, the baby’s arms are going to begin to lengthen and be more proportioned to the rest of the body. The liver is and be more proportioned to the rest of the body. The liver is beginning to produce bile, while the spleen is beginning to beginning to produce bile, while the spleen is beginning to produce red blood cells. The development of your baby’s brain produce red blood cells. The development of your baby’s brain enables him to use his facial muscles to grimace, frown, and enables him to use his facial muscles to grimace, frown, and squint. He may even be sucking his thumb.squint. He may even be sucking his thumb.

In week fifteen, the baby’s skin is very thin, and his blood vessels In week fifteen, the baby’s skin is very thin, and his blood vessels can actually be seen through the skin. The baby’s bones are can actually be seen through the skin. The baby’s bones are beginning to ossify, which means that if an x-ray was taken the beginning to ossify, which means that if an x-ray was taken the skeleton would be visible. skeleton would be visible.

In the sixteenth week, several of the more complicated body In the sixteenth week, several of the more complicated body systems are also beginning to function including the baby’s systems are also beginning to function including the baby’s urinary and circulatory system. The baby’s heart pumps around 25 urinary and circulatory system. The baby’s heart pumps around 25 quarts of blood per day. quarts of blood per day.

Second TrimesterSecond Trimester

Week seventeen, the baby’s umbilical cord is not only Week seventeen, the baby’s umbilical cord is not only lengthening but also becoming thicker and stronger for lengthening but also becoming thicker and stronger for these last 23 weeks. The baby’s sense of hearing is these last 23 weeks. The baby’s sense of hearing is also developing since the ears have fully formed and also developing since the ears have fully formed and moved into their final position. The baby is beginning to moved into their final position. The baby is beginning to form form adipose or fat tissue. Fat is important in helping or fat tissue. Fat is important in helping regulate the body’s temperature and metabolism.regulate the body’s temperature and metabolism.

In the eighteenth week, a protective covering called In the eighteenth week, a protective covering called myelin is beginning to form around the baby’s nerves. beginning to form around the baby’s nerves.

In week nineteen, the kidneys are making urine, and In week nineteen, the kidneys are making urine, and hair is beginning to sprout on the baby’s scalp. The hair is beginning to sprout on the baby’s scalp. The parts of the brain that are responsible for the senses parts of the brain that are responsible for the senses are specializing. If it is a baby girl, she already has 6 are specializing. If it is a baby girl, she already has 6 million eggs formed in her ovaries. million eggs formed in her ovaries.

Second TrimesterSecond Trimester

Week twenty the mother may begin to feel the Week twenty the mother may begin to feel the baby’s first movements known as quickening. baby’s first movements known as quickening. This is normally when an ultrasound can detect This is normally when an ultrasound can detect the sex of the baby.the sex of the baby.

In week twenty one, the baby’s digestive tract is In week twenty one, the baby’s digestive tract is continuing to mature. If the baby is a girl, then continuing to mature. If the baby is a girl, then her vagina has fully formed but will continue to her vagina has fully formed but will continue to develop until birth.develop until birth.

Week twenty four is when the taste buds are Week twenty four is when the taste buds are developing, and the lungs are becoming more developing, and the lungs are becoming more developed and complex. The branches of the developed and complex. The branches of the main lung are beginning to form as well as main lung are beginning to form as well as special cells that will produce surfactant. special cells that will produce surfactant. Surfactant is necessary for the air sacs to inflate Surfactant is necessary for the air sacs to inflate easily. easily.

In week twenty six, the nerves in the ears are In week twenty six, the nerves in the ears are developing and allowing the baby to respond developing and allowing the baby to respond more consistently to the sounds that they hear. If more consistently to the sounds that they hear. If it is a boy, his testicles have begun their descent it is a boy, his testicles have begun their descent into his scrotuminto his scrotum. .

Third TrimesterThird Trimester

Around week 27 to 28, the baby can open and close Around week 27 to 28, the baby can open and close their eyes. The baby has also developed a regular their eyes. The baby has also developed a regular wake and sleep cycle. wake and sleep cycle.

Up until this point, the baby’s brain has been relatively Up until this point, the baby’s brain has been relatively smooth, but beginning this week his brain will develop smooth, but beginning this week his brain will develop grooves and indentions along its surface. The amount grooves and indentions along its surface. The amount of brain tissue also begins to increase during the 28th of brain tissue also begins to increase during the 28th week. This causes the baby’s head to grow.week. This causes the baby’s head to grow.

In week thirty, the baby’s eyes are becoming more In week thirty, the baby’s eyes are becoming more mature, and now he can tell the difference between mature, and now he can tell the difference between light and dark. Babies at 30 weeks can even follow a light and dark. Babies at 30 weeks can even follow a light source with his eyes. light source with his eyes.

Third TrimesterThird Trimester

During the thirty second week, the baby’s toenails and During the thirty second week, the baby’s toenails and fingernails have formed. The lungs are continuing to fingernails have formed. The lungs are continuing to mature, but will not reach full maturity for several more mature, but will not reach full maturity for several more weeks. The baby’s skeleton has completely formed, weeks. The baby’s skeleton has completely formed, but his bones are very soft and pliable.but his bones are very soft and pliable.

In the thirty third week, the baby’s bones are all In the thirty third week, the baby’s bones are all beginning to harden except for the skull. The skull beginning to harden except for the skull. The skull needs to remain soft and pliable for delivery.needs to remain soft and pliable for delivery.

Week thirty four, the central nervous system is Week thirty four, the central nervous system is continuing to mature, and the lungs are well developed. continuing to mature, and the lungs are well developed. While most health care providers would ideally like the While most health care providers would ideally like the mother to carry up to 38 to 40 weeks, the baby has a mother to carry up to 38 to 40 weeks, the baby has a good chance of surviving outside of the uterus at this good chance of surviving outside of the uterus at this time. time.

Third TrimesterThird Trimester

By the thirty fifth week, the vast majority of the baby's By the thirty fifth week, the vast majority of the baby's growth is complete. Their kidneys are completely growth is complete. Their kidneys are completely developed, and the liver is beginning to process waste. developed, and the liver is beginning to process waste.

In week thirty six, the fine downy hair, lanugo, that has In week thirty six, the fine downy hair, lanugo, that has covered the baby’s skin is beginning to disappear, covered the baby’s skin is beginning to disappear, along with the vernix caseosa. Vernix caseosa is the along with the vernix caseosa. Vernix caseosa is the thick, creamy substance that has protected the baby’s thick, creamy substance that has protected the baby’s skin while he has been submerged in amniotic fluid. skin while he has been submerged in amniotic fluid. Both of these are swallowed by the baby, along with Both of these are swallowed by the baby, along with additional amniotic fluid, which combine together to additional amniotic fluid, which combine together to form meconium, the baby’s first bowel movement. form meconium, the baby’s first bowel movement.

By the end of week thirty seven, the baby is considered By the end of week thirty seven, the baby is considered full term.full term.

Third TrimesterThird Trimester

By the thirty eighth week, the vast majority of By the thirty eighth week, the vast majority of their organs are mature and fully functioning. their organs are mature and fully functioning. The only exceptions are the brain and lungs. The only exceptions are the brain and lungs. These two organs are at a point that they will These two organs are at a point that they will function outside of the womb, but will also function outside of the womb, but will also continue to mature during childhood.continue to mature during childhood.

In the last two weeks, the baby’s bones have In the last two weeks, the baby’s bones have become hard, with the exception of his skull. become hard, with the exception of his skull. The bones in the skull need to remain soft and The bones in the skull need to remain soft and pliable for delivery so that they can overlap as pliable for delivery so that they can overlap as they pass through the birth canal. they pass through the birth canal.

ReferencesReferences

http://www.americanpregnancy.org/durinhttp://www.americanpregnancy.org/duringpregnancy/gpregnancy/

http://www.mayoclinic.com/health/http://www.mayoclinic.com/health/medical/IM04051medical/IM04051