You can’t see it just yet, but your baby is already making big developmental strides, from swimming sperm to zygote to full fetus status, baby’s got a lot going on! Read on for a week by week pregnancy guide.
During
the first fourteen weeks, your baby goes from superstar swimming sperm
to a zygote—the term used to describe a fertilized egg in the first
four days—to an embryo, the term for your baby until about ten weeks’
gestation. By the second month, its poppy seed sized heart is beating,
other major organs are forming and your uterus is growing to about the
size of a peach. Your baby looks a lot more like a tadpole than a
human. It’s flat and it a has a tail and only limb buds.
Your tiny embryo graduates to a full fetus status by month three, and
you’ll be introduced to one of the new rituals of pregnancy—cold goo.
It seems that all baby exams require the slathering of supercold goo
on your belly, and few doctors or technicians try to warm it up. Your
first experience with the cold goo will probably be while hearing the
baby’s heartbeat by using a sound-wave stethoscope called a Doppler.
The cold goo will also be used for future sonograms. Hearing your
baby’s heartbeat for the very first time will likely be one of the most
thrilling “firsts” of your pregnancy. I took a tape recorder along with
me the first time, and would replay it for anyone who listened! Don’t
be frightened by how fast a baby’s heartbeat is, about one hundred
forty to one hundred sixty times per minute—are running a marathon in
there?—as this is normal and expected.
By the ninth week or so, the brain is growing like gangbusters. The
head makes up half of the fetus’s total length from the top of the head
to the butt. The baby looks more like E.T. than the cute, cuddly baby
you’re waiting for, but it’s still early days. By the end of the third
month, your baby will double in length, have separate fingers instead
of ones that are webbed, have all facial features including eyelids
that have opened and the fused shut by a thin membrane, have arms,
legs, thighs, and teeny toes. Meanwhile, your baby is taking his first
stab at doing something pretty gross—drinking his own urine. If you’re
thinking, he got that from his father! Don’t worry. The baby is
producing urine that is released into the amniotic fluid. Some of that
fluid is reabsorbed and the fetus swallows it, but it’s sterile and
harmless.
Here’s a Week by Week Pregnancy Guide from the experts at The Mayo Clinic:
Week 1: Getting ready
It may seem strange, but you're not actually pregnant the first week or
two of the time allotted to your pregnancy. Yes, you read that
correctly!
Conception typically occurs about two weeks after your period begins.
To calculate your due date, your health care provider will count ahead
40 weeks from the start of your last period. This means your period is
counted as part of your pregnancy — even though you weren't pregnant at
the time.
Week 2: Fertilization
The sperm and egg unite in one of your fallopian tubes to form a
one-celled entity called a zygote. If more than one egg is released and
fertilized, you may have multiple zygotes.
The zygote has 46 chromosomes — 23 from you and 23 from your partner.
These chromosomes contain genetic material that will determine your
baby's sex and traits such as eye color, hair color, height, facial
features and — at least to some extent — intelligence and personality.
Soon after fertilization, the zygote travels down the fallopian tube
toward the uterus. At the same time, it will begin dividing rapidly to
form a cluster of cells resembling a tiny raspberry. The inner group of
cells will become the embryo. The outer group of cells will become the
membranes that nourish and protect it.
Week 3: Implantation
The zygote — by this time made up of about 500 cells — is now known as
a blastocyst. When it reaches your uterus, the blastocyst will burrow
into the uterine wall for nourishment. The placenta, which will nourish
your baby throughout the pregnancy, also begins to form.
By the end of this week, you may be celebrating a positive pregnancy test.
Week 4: The embryonic period begins
The fourth week marks the beginning of the embryonic period, when the
baby's brain, spinal cord, heart and other organs begin to form. Your
baby is now 1/25 of an inch long.
The embryo is now made of three layers. The top layer — the ectoderm —
will give rise to a groove along the midline of your baby's body. This
will become the neural tube, where your baby's brain, spinal cord,
spinal nerves and backbone will develop.
Your baby's heart and a primitive circulatory system will form in the
middle layer of cells — the mesoderm. This layer of cells will also
serve as the foundation for your baby's bones, muscles, kidneys and
much of the reproductive system.
The inner layer of cells — the endoderm — will become a simple tube
lined with mucous membranes. Your baby's lungs, intestines and bladder
will develop here.
Week 5: Baby's heart begins to beat
Your baby at week five (three weeks after conception)
At week five, your baby is 1/17 of an inch long — about the size of the tip of a pen.
This week, your baby's heart and circulatory system are taking shape.
Your baby's blood vessels will complete a circuit, and his or her heart
will begin to beat. Although you won't be able to hear it yet, the
motion of your baby's beating heart may be detected with an ultrasound
exam.
With these changes, blood circulation begins — making the circulatory system the first functioning organ system.
Week 6: The neural tube closes
Your baby at week six (four weeks after conception)
Growth
is rapid this week. Just four weeks after conception, your baby is
about 1/8 of an inch long. The neural tube along your baby's back is
now closed, and your baby's heart is beating with a regular rhythm.
Basic
facial features will begin to appear, including an opening for the
mouth and passageways that will make up the inner ear. The digestive
and respiratory systems begin to form as well.
Small
blocks of tissue that will form your baby's connective tissue, ribs and
muscles are developing along your baby's midline. Small buds will soon
grow into arms and legs.
Week 7: The umbilical cord appears
Your baby at week seven (five weeks after conception)
Seven
weeks into your pregnancy, your baby is 1/3 of an inch long — a little
bigger than the top of a pencil eraser. He or she weighs less than an
aspirin tablet.
The umbilical cord — the link between your
baby and the placenta — is now clearly visible. The cavities and
passages needed to circulate spinal fluid in your baby's brain have
formed, but your baby's skull is still transparent.
The arm bud that sprouted last week now resembles a tiny paddle. Your
baby's face takes on more definition this week, as a mouth perforation,
tiny nostrils and ear indentations become visible.
Week 8: Baby's fingers and toes form
Eight weeks into your pregnancy, your baby is just over 1/2 of an inch long.
Your baby will develop webbed fingers and toes this week. Wrists,
elbows and ankles are clearly visible, and your baby's eyelids are
beginning to form. The ears, upper lip and tip of the nose also become
recognizable.
As your baby's heart becomes more fully developed, it will pump at 150 beats a minute — about twice the usual adult rate.
Week 9: Movement begins
Your baby at week nine (seven weeks after conception)
Your
baby is now nearly 1 inch long and weighs a bit less than 1/8 of an
ounce. The embryonic tail at the bottom of your baby's spinal cord is
shrinking, helping him or her look less like a tadpole and more like a
developing person.
Your baby's head — which is nearly half
the size of his or her entire body — is now tucked down onto the chest.
Nipples and hair follicles begin to form. Your baby's pancreas, bile
ducts, gallbladder and anus are in place. The internal reproductive
organs, such as testes or ovaries, start to develop.
Your baby may begin moving this week, but you won't be able to feel it for quite a while yet.
Week 10: Neurons multiply
Your baby at week 10 (eight weeks after conception)
By
now, your baby's vital organs have a solid foundation. The embryonic
tail has disappeared completely, and your baby has fully separated
fingers and toes. The bones of your baby's skeleton begin to form.
This week, your baby's brain will produce almost 250,000 new neurons every minute.
Your baby's eyelids are no longer transparent. The outer ears are
starting to assume their final form, and tooth buds are forming as
well. If your baby is a boy, his testes will start producing the male
hormone testosterone.
Week 11: Baby's sex may be apparent
Your baby at week 11 (nine weeks after conception)
From
now until your 20th week of pregnancy — the halfway mark — your baby
will increase his or her weight 30 times and will about triple in
length. To make sure your baby gets enough nutrients, the blood vessels
in the placenta are growing larger and multiplying.
Your
baby is now officially described as a fetus. Your baby's ears are
moving up and to the side of the head this week. By the end of the
week, your baby's external genitalia will develop into a recognizable
penis or clitoris and labia majora.
Week 12: Baby's fingernails and toenails appear
Twelve weeks into your pregnancy, your baby is nearly 3 inches long and
weighs about 4/5 of an ounce. Your baby's head is nearly half the size
of his or her entire body.
This week marks the arrival of fingernails and toenails. Your baby's chin and nose will become more refined as well.
For more great pregnancy advice, check out The Mocha Manual to a
Fabulous Pregnancy (Amistad/HarperCollins) by Kimberly Seals Allers and
The Mocha Manual DVD available at Wal-mart stores and walmart.com
During the first fourteen weeks, your baby goes from superstar swimming sperm to a zygote—the term used to describe a fertilized egg in the first four days—to an embryo, the term for your baby until about ten weeks’ gestation. By the second month, its poppy seed sized heart is beating, other major organs are forming and your uterus is growing to about the size of a peach. Your baby looks a lot more like a tadpole than a human. It’s flat and it a has a tail and only limb buds.
Your tiny embryo graduates to a full fetus status by month three, and you’ll be introduced to one of the new rituals of pregnancy—cold goo. It seems that all baby exams require the slathering of supercold goo on your belly, and few doctors or technicians try to warm it up. Your first experience with the cold goo will probably be while hearing the baby’s heartbeat by using a sound-wave stethoscope called a Doppler. The cold goo will also be used for future sonograms. Hearing your baby’s heartbeat for the very first time will likely be one of the most thrilling “firsts” of your pregnancy. I took a tape recorder along with me the first time, and would replay it for anyone who listened! Don’t be frightened by how fast a baby’s heartbeat is, about one hundred forty to one hundred sixty times per minute—are running a marathon in there?—as this is normal and expected.
By the ninth week or so, the brain is growing like gangbusters. The head makes up half of the fetus’s total length from the top of the head to the butt. The baby looks more like E.T. than the cute, cuddly baby you’re waiting for, but it’s still early days. By the end of the third month, your baby will double in length, have separate fingers instead of ones that are webbed, have all facial features including eyelids that have opened and the fused shut by a thin membrane, have arms, legs, thighs, and teeny toes. Meanwhile, your baby is taking his first stab at doing something pretty gross—drinking his own urine. If you’re thinking, he got that from his father! Don’t worry. The baby is producing urine that is released into the amniotic fluid. Some of that fluid is reabsorbed and the fetus swallows it, but it’s sterile and harmless.
Here’s a Week by Week Pregnancy Guide from the experts at The Mayo Clinic:
Week 1: Getting ready
It may seem strange, but you're not actually pregnant the first week or two of the time allotted to your pregnancy. Yes, you read that correctly!
Conception typically occurs about two weeks after your period begins. To calculate your due date, your health care provider will count ahead 40 weeks from the start of your last period. This means your period is counted as part of your pregnancy — even though you weren't pregnant at the time.
Week 2: Fertilization
The sperm and egg unite in one of your fallopian tubes to form a one-celled entity called a zygote. If more than one egg is released and fertilized, you may have multiple zygotes.
The zygote has 46 chromosomes — 23 from you and 23 from your partner. These chromosomes contain genetic material that will determine your baby's sex and traits such as eye color, hair color, height, facial features and — at least to some extent — intelligence and personality.
Soon after fertilization, the zygote travels down the fallopian tube toward the uterus. At the same time, it will begin dividing rapidly to form a cluster of cells resembling a tiny raspberry. The inner group of cells will become the embryo. The outer group of cells will become the membranes that nourish and protect it.
Week 3: Implantation
The zygote — by this time made up of about 500 cells — is now known as a blastocyst. When it reaches your uterus, the blastocyst will burrow into the uterine wall for nourishment. The placenta, which will nourish your baby throughout the pregnancy, also begins to form.
By the end of this week, you may be celebrating a positive pregnancy test.
Week 4: The embryonic period begins
The fourth week marks the beginning of the embryonic period, when the baby's brain, spinal cord, heart and other organs begin to form. Your baby is now 1/25 of an inch long.
The embryo is now made of three layers. The top layer — the ectoderm — will give rise to a groove along the midline of your baby's body. This will become the neural tube, where your baby's brain, spinal cord, spinal nerves and backbone will develop.
Your baby's heart and a primitive circulatory system will form in the middle layer of cells — the mesoderm. This layer of cells will also serve as the foundation for your baby's bones, muscles, kidneys and much of the reproductive system.
The inner layer of cells — the endoderm — will become a simple tube lined with mucous membranes. Your baby's lungs, intestines and bladder will develop here.
Week 5: Baby's heart begins to beat
Your baby at week five (three weeks after conception)
At week five, your baby is 1/17 of an inch long — about the size of the tip of a pen.
This week, your baby's heart and circulatory system are taking shape. Your baby's blood vessels will complete a circuit, and his or her heart will begin to beat. Although you won't be able to hear it yet, the motion of your baby's beating heart may be detected with an ultrasound exam.
With these changes, blood circulation begins — making the circulatory system the first functioning organ system.
Week 6: The neural tube closes
Your baby at week six (four weeks after conception)
Growth is rapid this week. Just four weeks after conception, your baby is about 1/8 of an inch long. The neural tube along your baby's back is now closed, and your baby's heart is beating with a regular rhythm.
Basic
facial features will begin to appear, including an opening for the
mouth and passageways that will make up the inner ear. The digestive
and respiratory systems begin to form as well.
Small
blocks of tissue that will form your baby's connective tissue, ribs and
muscles are developing along your baby's midline. Small buds will soon
grow into arms and legs.
Week 7: The umbilical cord appears
Your baby at week seven (five weeks after conception)
Seven weeks into your pregnancy, your baby is 1/3 of an inch long — a little bigger than the top of a pencil eraser. He or she weighs less than an aspirin tablet.
The umbilical cord — the link between your baby and the placenta — is now clearly visible. The cavities and passages needed to circulate spinal fluid in your baby's brain have formed, but your baby's skull is still transparent.
The arm bud that sprouted last week now resembles a tiny paddle. Your baby's face takes on more definition this week, as a mouth perforation, tiny nostrils and ear indentations become visible.
Week 8: Baby's fingers and toes form
Eight weeks into your pregnancy, your baby is just over 1/2 of an inch long.
Your baby will develop webbed fingers and toes this week. Wrists, elbows and ankles are clearly visible, and your baby's eyelids are beginning to form. The ears, upper lip and tip of the nose also become recognizable.
As your baby's heart becomes more fully developed, it will pump at 150 beats a minute — about twice the usual adult rate.
Week 9: Movement begins
Your baby at week nine (seven weeks after conception)
Your baby is now nearly 1 inch long and weighs a bit less than 1/8 of an ounce. The embryonic tail at the bottom of your baby's spinal cord is shrinking, helping him or her look less like a tadpole and more like a developing person.
Your baby's head — which is nearly half the size of his or her entire body — is now tucked down onto the chest. Nipples and hair follicles begin to form. Your baby's pancreas, bile ducts, gallbladder and anus are in place. The internal reproductive organs, such as testes or ovaries, start to develop.
Your baby may begin moving this week, but you won't be able to feel it for quite a while yet.
Week 10: Neurons multiply
Your baby at week 10 (eight weeks after conception)
By now, your baby's vital organs have a solid foundation. The embryonic tail has disappeared completely, and your baby has fully separated fingers and toes. The bones of your baby's skeleton begin to form.
This week, your baby's brain will produce almost 250,000 new neurons every minute.
Your baby's eyelids are no longer transparent. The outer ears are starting to assume their final form, and tooth buds are forming as well. If your baby is a boy, his testes will start producing the male hormone testosterone.
Week 11: Baby's sex may be apparent
Your baby at week 11 (nine weeks after conception)
From now until your 20th week of pregnancy — the halfway mark — your baby will increase his or her weight 30 times and will about triple in length. To make sure your baby gets enough nutrients, the blood vessels in the placenta are growing larger and multiplying.
Your baby is now officially described as a fetus. Your baby's ears are moving up and to the side of the head this week. By the end of the week, your baby's external genitalia will develop into a recognizable penis or clitoris and labia majora.
Week 12: Baby's fingernails and toenails appear
Twelve weeks into your pregnancy, your baby is nearly 3 inches long and weighs about 4/5 of an ounce. Your baby's head is nearly half the size of his or her entire body.
This week marks the arrival of fingernails and toenails. Your baby's chin and nose will become more refined as well.
For more great pregnancy advice, check out The Mocha Manual to a Fabulous Pregnancy (Amistad/HarperCollins) by Kimberly Seals Allers and The Mocha Manual DVD available at Wal-mart stores and walmart.com
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