1. Prenatal Development
Weeks 1-40

2. Conception Ovum: female cell or egg
Uterus: organ in a woman’s body in which the baby develops
Sperm: male cell
Conception: when the ovum and the sperm unite
Ovum lives up to 24 hours after release from ovary
Sperm lives up to 72 hours after release from male

3. Week 1 The first week is your menstrual period.
Your pregnancy will be dated from this:
Most women don't know the precise moment they have ovulated or conceived.
Most do remember the first day of their last menstrual period.

4. Week 2
The very end of the second week marks the release of the egg—ovulation
At this point in your cycle, your uterine lining is developing under the influence of hormone your body secretes to make it receptive to the fertilized egg.

5. Week 3
Right between weeks two and three (about day 14 of a 28-day cycle) an egg will be released into your fallopian tube—this is called "ovulation."
Some women can tell when they ovulate by noting mild cramping or pain or increased vaginal discharge.
Once the egg has been released, it must be fertilized for you to become pregnant.
The egg is fertilized early in the third week and typically implants in the uterus 6-12 days after ovulation.

6. Stages of the Zygote Zygote is the fertilized egg
Cells will divide at rapid rate
Within 5 days there will be over 500 cells.
Travels down fallopian tube and attaches to uterus
This stage last only 2 weeks
About the size of a pin head.

7. Stage of the Embryo
Lasts from the time the cells attach to uterus to week 12.
Embryo: ball of rapidly multiplying cells
Almost all of the internal organs begin to develop during this six-week stage
Embryo also becomes enclosed in a fluid-filled pouch called the amniotic sac.

8. Embryo Key Terms
Placenta: tissue connecting the embryo to the uterine wall.
Umbilical cord: attaches the embryo the the placenta.
Amniotic fluid: fluid inside amniotic sac. Protects the developing baby from falls that a mother might have.

9. Week 4
The fertilized egg is a fluid-filled cluster of rapidly multiplying cells.
The egg tunnels into the uterus where it promptly divides into two parts.
Half the egg attaches to the uterine wall and develops into the placenta
will transport oxygen and nutrients to your baby
Transports waste products away from your little
The other half will develop into the embryo, which will later become the fetus.
During this week the following occurs:
Spinal cord development. A sheet of cells on the back of the embryo folds in the middle to form a tube that will become the baby's spinal cord.
Brain section development. At the other end, the tube enlarges to form the brain's major sections.
What's happening with you
Pregnancy symptoms
Missed period and possible spotting

10. What’s happening with you.
Week 5
Your baby’s growth:
Embryo cell layers
What’s happening with you.
Just a bit bigger than an apple seed.
Embryo' has already divided into three layers
The top layer: Neural folds create a tube which will form the front part of brain, the heart which will beat this week, and the spinal cord and back bone
The middle layer. These cells will produce the circulatory system, bones, most muscles, cartilage, sex organs and kidneys.
The bottom layer. These cells will form the lungs, intestines and beginnings of the urinary system.
Missed period. You should have missed your period or have experienced slight spotting.
Pregnancy symptoms. As your blood flow works to catch up with your rapidly expanding circulatory system, you may experience morning sickness (nausea), and fatigue.
Unappetizing smells and tastes. It may help to avoid foods with very strong smells or tastes, such as oily or fried foods and spicy dishes. Even strong-smelling cleaners and disinfectants may bother you right now.
If you aren't experiencing these symptoms, don't be concerned. You may be one of the lucky moms who sail through early pregnancy without feeling nauseous at all.

11. Week 6 Your baby’s growth Your body About the size of a kidney bean.
Developing this week:
Eye retina is forming
Neural tube
Heart
Limbs
Brain
Larynx and inner ear
Neck and lower jaw
Facial features
Organs
Placenta
Breast changes.
Become larger and more sensitive.
Tingling sensations
Areola may start to darken.
Weight change.
May have gained two or three pounds..
Morning sickness.
May get worse this week as your hormone levels rise.
Perfectly normal for nausea to appear at any point of the day or night.
Your baby's growth: Organs, eyes, limbs and more
Your baby is still very tiny … only about the size of a kidney bean. But this is a big week as organs and parts of the body begin to take shape.
Will your baby's eyes be brown, blue, green, or hazel? It's much too early to know, but by week six the eyes are beginning to develop and the earliest version of the retina is forming.
Here's what else is developing:
Neural tube. The neural tube, which connects the brain and spinal cord, will close this week. This is good news because when the neural tube closes, your little one is much less likely to develop brain or spine defects such as spina bifida. However, it will be several weeks before the heartbeat can be heard with an instrument.
Heart. Still located on the outside of the body, the heart is dividing into chambers and will find a more regular rhythm soon.
Limbs. Upper and lower limb buds are forming on the body and will eventually develop into arms and legs.
Brain. The brain begins to fill your baby's tiny skull.
Larynx and inner ear.
Neck and lower jaw. Below the opening that will later form your baby's mouth are small folds where the neck and the lower jaw will eventually develop.
Facial features. As nostrils become distinct, facial features are already forming.
Organs. The kidneys, liver, pancreas, lungs, stomach and intestines are developing.
Placenta. The lining of the placenta develops. Its extensive blood flow structures provide the oxygen and nutrients your baby needs for its growth.
Fetal risks
Because the internal organs and limbs are in such an early stage of development, the embryo is sensitive to some drugs and viruses that might get past the placental barrier. Most birth defects begin between weeks four and eight of development—six to 10 weeks of pregnancy.
First movements
Halfway through this week the embryo will make her first movements, but you'll have to wait until your second trimester before you can actually feel your baby's wiggles.
What's happening with you
Breast changes. Hormonal changes may cause your breasts to become larger and more sensitive. You may even be experiencing tingling sensations and the areola may start to darken.
Weight change. You may have gained two or three pounds. But if you've been experiencing morning sickness, you may actually have lost some weight.
Morning sickness. If you're experiencing nausea, it may get worse this week as your hormone levels rise. Although it's called "morning sickness," it's perfectly normal for nausea to appear at any point of the day or night.
Protecting your baby
This is the time in your pregnancy when you'll need to be especially careful about toxins and infections. That's because your baby is especially vulnerable to birth defects in the first three months.
Don't change your cat's litter. If you have a cat, ask a family member to change the litter to avoid risk of toxoplasmosis, an infection caused by parasites common in cat feces. It can be passed from Mom to baby.
Check with your doctor before taking any medication— even those that you can buy without a prescription.
Don't handle insecticides or other poisonous substances

12. Week 7 Weight gain Morning sickness More bathroom breaks
Your baby’s growth
Your body
Weight gain
Morning sickness
More bathroom breaks
Increased energy
About 1 inch long.
Fetal digestive system is beginning to develop. The umbilical cord, has started taking shape. This ropelike cord contains two arteries and a vein. It brings oxygen and nutrients to the embryo and carries away waste products.
Facial features
Ears
Eyes
Head
Heart
Airways
Mouth
Skin
Your baby's growth: Fetal digestion system, umbilical cord
This week the embryo will more than double in size, growing from a bit more than 1/8 of an inch long to about half an inch. She still has a lot more growing to do: The average newborn is 18 to 21 inches long and weighs six to nine pounds.
Right about now the fetal digestive system is beginning to develop. Your baby's most important prenatal connection to you, the umbilical cord, has started taking shape. This ropelike cord contains two arteries and a vein. It brings oxygen and nutrients to the embryo and carries away waste products.
You can now see your little embryo on an ultrasound, which might show some of the following:
Facial features. Tiny nostrils and a minuscule mouth have started to develop.
Ears. Indentations are appearing where ears will be.
Eyes. Your little one is developing more distinct eyes, with pigmented irises.
Head. Your baby's head is still much larger than the rest of the body, but her body will grow rapidly this week.
Heart. A quickly beating heart (about 150 beats per minute) with two chambers is developing.
Airways. Bronchial tubes are developing to carry air through the lungs and carbon dioxide out of the lungs.
Mouth. Tooth buds and palate are just beginning to grow.
Skin. Your baby has paper-thin skin with clearly visible blood vessels.
What's happening with you
Weight gain. It's not quite time for maternity clothes since you're still not showing. But you may have gained a few pounds if you haven't been too nauseated to eat.
Morning sickness. During this first trimester, many women complain of morning sickness, caused in part by pregnancy hormones.
More bathroom breaks. Another change you may notice is frequent urination. As your enlarging uterus presses on the bladder and hormones affect your fluid balance, you'll probably need to use the bathroom more often than before.
Increased energy. If you're getting enough rest, you may begin to have more energy now.

13. Week 8 Rollercoaster of emotions
Your baby’s growth
Your body
Rollercoaster of emotions
Breast enlargement and bigger waistline
Cramping
First doctor’s visit
Head will become more rounded as the embryo begins to look more like a baby.
Body begins to fine-tune its bone, joint and limb development, and tiny finger and toe buds appear.
Eyelids are forming
Nose
Blood beginning to flow
Digestive tract continues to develop
Gonads transform into either testes or ovaries
Ears
Elbows
Vertebrae
Muscles
Skin
Your baby's growth: Bone, joint and limb development
She's about half an inch long, and by next week or so her head will become more rounded as the embryo begins to look more like a baby.
Week 8 is the time her body begins to fine-tune its bone, joint and limb development, and tiny finger and toe buds appear. She may someday use her hands to sculpt or perform surgery, but right now those hands are little nubs.
There are a lot of other things happening as well:
Eyelids are beginning to form.
The tip of your baby's nose is taking shape.
Blood is beginning to flow through a rudimentary circulatory system.
Digestive tract continues to develop.
Gonads are beginning to transform themselves into either testes or ovaries.
Ears are developing both inside and out.
Elbows have just started to appear.
Vertebrae and ribs are beginning to grow.
Muscles and two layers of skin are forming.
What's happening with you
New emotions. You may soon find yourself experiencing an emotional roller coaster of highs and lows as you feel excited one day and irritable the next. These mood swings may take you by surprise! But take comfort in knowing that this is a common pregnancy symptom, as hormone levels are fluctuating dramatically.
Breast enlargement and bigger waistline. Your pregnancy is starting to change your figure as well as your moods. Your breasts are enlarging and your waistline is starting to grow.
Cramping. Even though you may not be showing yet, your uterus has grown from about the size of a fist to as big as a grapefruit. As your uterus grows, it's normal to feel some cramping, discomfort or tightening.
First doctor's visit. You've probably scheduled your first office visit for urine and blood tests, a general physical examination, baseline blood pressure evaluation, weight check, pelvic exam, Pap smear and a review of your family health history.

14. Week 9 Increased blood volume Fatigue Testing CVS Amniocentesis
Your baby’s growth
Your body
About the size of a peapod and weighs a little less than half an ounce.
Muscles, nerves and organs are forming.
Genitals are beginning to develop, but it's still almost impossible to tell on ultrasound whether you're going to have a boy or a girl.
Increased body growth
Digits
Digestive system
Eyelids
Ears
Brain
Increased blood volume
Fatigue
Testing
CVS
Amniocentesis
Your baby's growth: Muscles, nerves and organs
Your baby has now grown to about the size of a peapod and weighs a little less than half an ounce.
Week 9 continues the stage when your baby's muscles, nerves and organs are forming. She'll move away if you press against the uterine wall when you touch your belly, but you won't be able to feel her moving for several more weeks. Genitals are beginning to develop, but it's still almost impossible to tell on ultrasound whether you're going to have a boy or a girl.
By week nine your baby's growth includes:
Increased body growth. Her head is quite large compared with the rest of her body, and it curves onto her chest. Her arms have grown, her hands are now flexed at the wrists, and her legs are lengthening. Her feet may be long enough to meet in front of the body.
Digits. She's developing clearly visible fingers and toes.
Digestive system. This continues to develop.
Eyelids. Developing eyelids begin to cover the eyes and fuse together. Her eyes won't open until about week 27.
Ears. Development of the inner and external ears is almost complete.
Brain. She's far from being conscious, but she's experiencing the first nerve connections in the brain.
What's happening with you
Increased blood volume. Although you still haven't gained much weight, your blood volume continues to increase. By the end of nine months your body will have produced 30 to 35 percent more blood to meet the demands of your baby.
Fatigue. You may continue to feel tired, nauseated and dizzy, but take heart: This will most likely fade away soon.
Testing. If you're over age 35 or have a family history of genetic illness, at this stage you may want to talk with your doctor about prenatal genetic diagnosis. Chorionic villus sampling (CVS) is usually done between 10 and 12 weeks and screens for birth defects. Amniocentesis is performed about 4 weeks later. Both tests screen for certain types of birth defects, such as Down syndrome. And both tests have risks of miscarriage (CVS carries a higher risk than the amniocentesis) that should be carefully discussed with your doctor.
If you've been identified as being high risk for other disorders, such as Tay-Sachs or cystic fibrosis (based on your family health history), your doctor may want you to be tested for those conditions as well

15. Week 10 Still in regular clothes Fatigue and nausea Baby’s growth
Your body
Teeth
Reproductive organs
Nervous system
Internal organs
Intestines
Taste buds
Eyelids
Upper lip
Joints
Still in regular clothes
Fatigue and nausea
Your baby's growth: Brain
This week your baby's brain will experience enormous growth. The rest of her body is growing too; she's now about the size of a small plum and weighs about half an ounce.
This week marks your baby's last week as an embryo; next week she'll officially become a fetus.
But this week there's still a lot of activity going on:
Teeth. Tooth buds for baby teeth will begin forming inside the mouth.
Reproductive organs and external genitals. They will be formed, although it will still be too early to determine gender.
Nervous system. This will continue to develop.
Internal organs. Many of the internal organs will begin to function.
Intestines. They have been developing inside the umbilical cord and have begun moving into the abdominal cavity.
Taste buds. They will begin to appear on the surface of the tiny tongue.
Eyelids. They're almost closed over the tiny eyes, which have already developed some of the color they'll have at birth.
Upper lip. This will form completely.
Joints. Most of the joints will form, including elbows, wrists, knees, shoulders and ankles.
What's happening with you
You're still in regular clothes. Despite your baby's growth spurt, you can probably still wear your regular clothes. Very little of your total pregnancy weight gain—usually between 25 and 35 pounds if pre-pregnancy weight was normal—occurs during the first three months.
Fatigue and nausea. If you're still feeling tired and a little sick, try to focus on the fact that in just a few more weeks, you'll probably be feeling a lot better!

16. Week 11 Uterus expansion Waist growth
Baby’s growth
Your body
Fingernails
Ears
Genitalia
Swallow
Kick
Bones
Brain nerve cells connecting
All major organs will be fully developed
Spinal nerves
Heartbeat
Uterus expansion
Waist growth
Skin changes: dark line on abdomen
Hair and nail changes
Your baby's growth: Fingernails appear
By the end of this week your baby will be about two inches from head to bottom and still weigh about half an ounce—but she'll double in size and weight over the next three weeks. Other changes you can expect this week:
Ears. Your baby's ears will move toward their final position on the sides of her head.
Genitalia. Your baby's external genitalia are beginning to develop, and in a few weeks an ultrasound exam may tell you whether you're having a boy or girl.
Action! Your baby will begin to swallow and kick.
Bones. They will begin to slowly solidify, although most of the skeleton is still made of flexible material.
Brain. Nerve cells in the brain are busy connecting with each other, building pathways for future communication.
All major organs will be fully developed.
Spinal nerves. They will begin to stretch out from the spinal cord.
Fingernails will begin to appear.
Heartbeat. With a special handheld device, your doctor will be able to hear the fetus' rapid heartbeat.
What's happening with you
Uterus expansion. As you approach the end of the first trimester, your uterus continues to expand, almost filling your pelvis as it supports your growing baby.
Waist growth. Although you probably won't need to start wearing maternity clothes for a few more weeks, your waist is continuing to grow.
Skin changes. Your changing hormones have triggered an increase in your skin's production of melanin, which results in the development of a dark vertical line of pigmentation on your abdomen, called the linea nigra. This line is a common sign of pregnancy and will fade, although it may not disappear completely , after pregnancy. The fairer-skinned you are, the less noticeable this line will be, during and after pregnancy.
Hair and nail changes. Hormones also affect hair and nails. Many women discover that during pregnancy their nails grow faster and their hair stops shedding. As a result your hair will seem thicker and fuller than ever before.
A word of caution: Although it has never been proven that hair dyes or perming chemicals harm a developing fetus, it's a good idea to avoid these procedures until after your first trimester, or even better, until after your little one is born.

17. Week 12 Uterus enlargement Skin radiance Skin problems
Baby’s growth
Your body
Had developed a facial profile
Kidneys
Pancreas
Liver
Digestive process
Brain
Pituitary gland with begin to produce hormones
Hair (lanugo) will appear all over the body
Uterus enlargement
Skin radiance
Skin problems
Nausea and fatigue goes away
Weight gain
Your baby's growth: A facial profile
Your baby continues to grow and is now about 3 inches long. By Week 12 your baby has a profile, complete with a little chin and a tiny nose. Inside the mouth folded tissues join to form the palate, or roof of the mouth, which separates the oral and nasal cavities.
Some other fascinating things will happen in the 12th week:
Kidneys. Amniotic fluid will build up as your baby's kidneys begin to produce and excrete urine into the fluid.
Pancreas. It will begin to produce insulin, a hormone that regulates blood sugar levels.
Liver. It will start to secrete bile, a thick, greenish fluid stored in the gall bladder that helps the body digest fats.
Digestive process. The muscles in the intestinal walls will begin to practice contractions. Basically your baby is practicing the digestive processes that will begin once she is born.
Brain. The brain's basic structure is intact by the end of the week, and brain mass is growing all the time.
Pituitary gland will begin to produce hormones.
Hair. Soft, non-pigmented hair—believed to protect your baby's skin before birth—will begin to appear on your little one's body. Most of this hair, called lanugo, will disappear soon after birth.
What's happening with you
Uterus enlargement. Sometime during this week your uterus will probably move upward and forward as it continues to enlarge. This means the pressure on your bladder will temporarily ease. Eventually however your uterus will get large enough so that it will again push against the bladder, increasing your need to urinate. About now you will find that your expanding abdomen will make regular clothes seem tight, and you may decide to start wearing maternity garments.
Skin radiance. During this week you may notice your skin becoming more radiant due to your increased blood volume and pregnancy hormones. As more blood flows through your blood vessels and hormones increase oil gland secretion, you may experience flushed, plumper, smoother skin.
Skin problems. Hormone-related oil activity may have other effects on your skin, such as temporary acne or brown patches called chloasma on the face or neck. Not to worry: Most of these skin problems are only temporary, and many disappear after birth.
Nausea and fatigue goes away. Many women now start to feel better in the pregnancy as fatigue and nausea fade away.
Weight gain. Because of hormonal changes as your body prepares for childbirth, you may notice that you're gaining weight in your hips, legs and sides. As a result you might feel more comfortable in loose-fitting, early-stage-pregnancy clothes.

18. Congrats! You have concluded the 1st trimester!
All body parts are in place, it will just continue to grow.

19. Stage of the Fetus 3rd and final stage of prenatal development
Weeks 9-40
Unborn child is called fetus
Body, head, arms, and legs grow rapidly
Organs continue to develop for blood circulation, breathing, and digestion