Facts you should know about pregnancy week to week*
A typical pregnancy lasts for 40 weeks.
*Pregnancy facts medical author: Melissa Conrad Stöppler, MD
- A normal pregnancy lasts about 40 weeks and is grouped into three stages, or trimesters.
- Symptoms and early signs of pregnancy that begin in the first semester include:
- The absence of menstrual periods
- Breast changes including swelling or tenderness
- Tiredness
- Nausea
- Mood swings
- Other symptoms
- A pregnancy test measures the level of hormone human chorionic gonadotropin (HCG) in the urine or blood. The test may be positive before the first signs of pregnancy develop in some women.
- Symptoms of late second and third trimesters of pregnancy can include:
- Heartburn
- Difficulty sleeping
- Swelling of the ankles or fingers
- Hemorrhoids
- Mild contractions
- Many of the later symptoms result from the weight gain and enlarging uterus in late pregnancy.
- By the end of 37 weeks, a baby is considered full term and its organs are ready to function on their own.
- As you near your due date, your baby may turn into a head-down position for birth. Most babies "present" head down.
- Babies at birth typically weigh between 6 pounds 2 ounces and 9 pounds 2 ounces and are 19 to 21 inches long. Most full-term babies fall within these ranges.
Pregnant or Not? How to Know
To learn whether you are pregnant or not, a pregnancy test may provide you with the answer. This test can be done in the privacy of your home using one of several available test kits. Or the test can be performed in your doctor?s office or clinic. Home pregnancy tests are always done on urine while those in a doctor?s office or clinic may be done on urine or blood.
Read more about pregnancy tests »
How many weeks is a normal term pregnancy?
Pregnancy lasts about 40 weeks, counting from the first day of your last normal period. The weeks are grouped into three trimesters.
What is the first trimester of pregnancy (week 1-week 12)?
Your period stopping is a clear sign that you are pregnant. Other changes may include extreme tiredness, tender, swollen breasts, and your nipples might also stick out.
During the first trimester, your body undergoes many changes. Hormonal changes affect almost every organ system in your body. These changes can trigger symptoms even in the very first weeks of pregnancy. Your period stopping is a clear sign that you are pregnant. Other changes may include:
- Extreme tiredness
- Tender, swollen breasts. Your nipples might also stick out.
- Upset stomach with or without throwing up (morning sickness)
- Cravings or distaste for certain foods
- Mood swings
- Constipation (trouble having bowel movements)
- Need to pass urine more often
- Headache
- Heartburn
- Weight gain or loss
As your body changes, you might need to make changes to your daily routine, such as going to bed earlier or eating frequent, small meals. Fortunately, most of these discomforts will go away as your pregnancy progresses. And some women might not feel any discomfort at all! If you have been pregnant before, you might feel differently this time around. Just as each woman is different, so is each pregnancy.
IMAGES
Pregnancy (Week By Week, Trimesters)
See pictures of a growing fetus through the 3 stages of pregnancy
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What is the second trimester of pregnancy (week 13-week 28)?
Most women find the second trimester of pregnancy easier than the first. But it is just as important to stay informed about your pregnancy during these months.
You might notice that symptoms like nausea and fatigue are going away. But other new, more noticeable changes to your body are now happening. Your abdomen will expand as the baby continues to grow. And before this trimester is over, you will feel your baby beginning to move!
As your body changes to make room for your growing baby, you may have:
- Body aches, such as back, abdomen, groin, or thigh pain
- Stretch marks on your abdomen, breasts, thighs, or buttocks
- Darkening of the skin around your nipples
- A line on the skin running from belly button to pubic hairline
- Patches of darker skin, usually over the cheeks, forehead, nose, or upper lip. Patches often match on both sides of the face. This is sometimes called the mask of pregnancy
- Numb or tingling hands called carpal tunnel syndrome
- Itching on the abdomen, palms, and soles of the feet. (Call your doctor if you have nausea, loss of appetite, vomiting, jaundice or fatigue combined with itching. These can be signs of a serious liver problem.)
- Swelling of the ankles, fingers, and face. (If you notice any sudden or extreme swelling or if you gain a lot of weight really quickly, call your doctor right away. This could be a sign of preeclampsia.)
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What is the third trimester trimester of pregnancy (week 29-week 40)?
You're in the home stretch! Some of the same discomforts you had in your second trimester will continue. Plus, many women find breathing difficult and notice they have to go to the bathroom even more often. This is because the baby is getting bigger and it is putting more pressure on your organs. Don't worry, your baby is fine and these problems will lessen once you give birth.
Some new body changes you might notice in the third trimester include:
- Shortness of breath
- Heartburn
- Swelling of the ankles, fingers, and face. (If you notice any sudden or extreme swelling or if you gain a lot of weight really quickly, call your doctor right away. This could be a sign of preeclampsia.)
- Hemorrhoids
- Tender breasts, which may leak a watery pre-milk called colostrum
- Your belly button may stick out
- Trouble sleeping
- The baby "dropping," or moving lower in your abdomen
- Contractions, which can be a sign of real or false labor
As you near your due date, your cervix becomes thinner and softer (called effacing). This is a normal, natural process that helps the birth canal to open during the birthing process. Your doctor will check your progress with a vaginal exam as you near your due date. Get excited — the final countdown has begun!
How will my baby develop week by week?
First Trimester (week 1-week 12)
At 4 to 5 weeks:
- Your baby's brain and spinal cord have begun to form.
- The heart begins to form.
- Arm and leg buds appear.
- Your baby is now an embryo and one-twenty-fifth inch long.
At 8 weeks:
- All major organs and external body structures have begun to form.
- Your baby's heart beats with a regular rhythm.
- The arms and legs grow longer, and fingers and toes have begun to form.
- The sex organs begin to form.
- The eyes have moved forward on the face and eyelids have formed.
- The umbilical cord is clearly visible.
- At the end of 8 weeks, your baby is a fetus and looks more like a human. Your baby is nearly 1 inch long and weighs less than 1/8 of an ounce.
At 12 weeks:
- The nerves and muscles begin to work together. Your baby can make a fist.
- Eyelids close to protect the developing eyes. They will not open again until the 28th week.
- Head growth has slowed, and your baby is much longer. Now, at about 3 inches long, your baby weighs almost an ounce.
Second Trimester (week 13-week 28)
At 16 weeks:
- The external sex organs show if your baby is a boy or girl. A woman who has an ultrasound in the second trimester or later might be able to find out the baby's sex.
- Muscle tissue and bone continue to form, creating a more complete skeleton.
- Skin begins to form. You can nearly see through it.
- Meconium (mih-KOH-nee-uhm) develops in your baby's intestinal tract. This will be your baby's first bowel movement.
- Your baby makes sucking motions with the mouth (sucking reflex).
- Your baby reaches a length of about 4 to 5 inches and weighs almost 3 ounces.
At 20 weeks:
- Your baby is more active. You might feel slight fluttering.
- Your baby is covered by fine, downy hair called lanugo (luh-NOO-goh) and a waxy coating called vernix. This protects the forming skin underneath.
- Eyebrows, eyelashes, fingernails, and toenails have formed. Your baby can even scratch itself.
- Your baby can hear and swallow.
- Now halfway through your pregnancy, your baby is about 6 inches long and weighs about 9 ounces.
At 24 weeks:
- Bone marrow begins to make blood cells.
- Taste buds form on your baby's tongue.
- Footprints and fingerprints have formed.
- Real hair begins to grow on your baby's head.
- The lungs are formed, but do not work.
- The hand and startle reflex develop.
- Your baby sleeps and wakes regularly.
- If your baby is a boy, his testicles begin to move from the abdomen into the scrotum. If your baby is a girl, her uterus and ovaries are in place, and a lifetime supply of eggs have formed in the ovaries.
- Your baby stores fat and has gained quite a bit of weight. Now at about 12 inches long, your baby weighs about 1½ pounds.
Third Trimester (week 29-week 40)
At 32 weeks:
- Your baby's bones are fully formed, but still soft.
- Your baby's kicks and jabs are forceful.
- The eyes can open and close and sense changes in light.
- Lungs are not fully formed, but practice "breathing" movements occur.
- Your baby's body begins to store vital minerals, such as iron and calcium.
- Lanugo begins to fall off.
- Your baby is gaining weight quickly, about one-half pound a week. Now, your baby is about 15 to 17 inches long and weighs about 3 to 41⁄2 pounds
At 36 weeks:
- The protective waxy coating called vernix gets thicker.
- Body fat increases. Your baby is getting bigger and bigger and has less space to move around. Movements are less forceful, but you will feel stretches and wiggles.
- Your baby is about 16 to 19 inches long and weighs about 6 to 6½ pounds.
Weeks 37-40:
- By the end of 37 weeks, your baby is considered full term. Your baby's organs are ready to function on their own.
- As you near your due date, your baby may turn into a head-down position for birth. Most babies "present" head down.
- At birth, your baby may weigh somewhere between 6 pounds 2 ounces and 9 pounds 2 ounces and be 19 to 21 inches long. Most full-term babies fall within these ranges. But healthy babies come in many different sizes.
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What are the changes that happen to a woman's body during the 1st, 2nd, and 3rd trimester of her pregnancy?
Everyone expects pregnancy to bring an expanding waistline. But many women are surprised by the other body changes that pop up. Get the low-down on stretch marks, weight gain, heartburn and other "joys" of pregnancy. Find out what you can do to feel better.
Body aches
As your uterus expands, you may feel aches and pains in the back, abdomen, groin area, and thighs. Many women also have backaches and aching near the pelvic bone due the pressure of the baby's head, increased weight, and loosening joints. Some pregnant women complain of pain that runs from the lower back, down the back of one leg, to the knee or foot. This is called sciatica. It is thought to occur when the uterus puts pressure on the sciatic nerve.
What might help:
- Lie down.
- Rest.
- Apply heat.
Call the doctor if the pain does not get better.
Breast changes
A woman's breasts increase in size and fullness during pregnancy. As the due date approaches, hormone changes will cause your breasts to get even bigger to prepare for breastfeeding. Your breasts may feel full, heavy, or tender.
In the third trimester, some pregnant women begin to leak colostrum from their breasts. Colostrum is the first milk that your breasts produce for the baby. It is a thick, yellowish fluid containing antibodies that protect newborns from infection.
What might help:
- Wear a maternity bra with good support.
- Put pads in the bra to absorb leakage.
Tell your doctor if you feel a lump or have nipple changes or discharge (that is not colostrum) or skin changes.
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Constipation
Many pregnant women complain of constipation. Signs of constipation include having hard, dry stools; fewer than three bowel movements per week; and painful bowel movements.
Higher levels of hormones due to pregnancy slow down digestion and relax muscles in the bowels leaving many women constipated. Plus, the pressure of the expanding uterus on the bowels can contribute to constipation.
What might help:
- Drink 8 to 10 glasses of water daily.
- Don't drink caffeine.
- Eat fiber-rich foods, such as fresh or dried fruit, raw vegetables, and whole-grain cereals and breads.
- Try mild physical activity
Tell your doctor if constipation does not go away.
Dizziness
Many pregnant women complain of dizziness and lightheadedness throughout their pregnancies. Fainting is rare but does happen even in some healthy pregnant women. There are many reasons for these symptoms. The growth of more blood vessels in early pregnancy, the pressure of the expanding uterus on blood vessels, and the body's increased need for food all can make a pregnant woman feel lightheaded and dizzy.
What might help:
- Stand up slowly.
- Avoid standing for too long.
- Don't skip meals.
- Lie on your left side.
- Wear loose clothing.
Call your doctor if you feel faint and have vaginal bleeding or abdominal pain.
QUESTION
Nothing can relieve the symptoms of morning sickness.
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Fatigue, sleep problems
During your pregnancy, you might feel tired even after you've had a lot of sleep. Many women find they're exhausted in the first trimester. Don't worry, this is normal! This is your body's way of telling you that you need more rest. In the second trimester, tiredness is usually replaced with a feeling of well being and energy. But in the third trimester, exhaustion often sets in again. As you get larger, sleeping may become more difficult. The baby's movements, bathroom runs, and an increase in the body's metabolism might interrupt or disturb your sleep. Leg cramping can also interfere with a good night's sleep.
What might help:
- Lie on your left side.
- Use pillows for support, such as behind your back, tucked between your knees, and under your tummy.
- Practice good sleep habits, such as going to bed and getting up at the same time each day and using your bed only for sleep and sex.
- Go to bed a little earlier.
- Nap if you are not able to get enough sleep at night.
- Drink needed fluids earlier in the day, so you can drink less in the hours before bed.
Heartburn and indigestion
Hormones and the pressure of the growing uterus cause indigestion and heartburn. Pregnancy hormones slow down the muscles of the digestive tract. So food tends to move more slowly and digestion is sluggish. This causes many pregnant women to feel bloated.
Hormones also relax the valve that separates the esophagus from the stomach. This allows food and acids to come back up from the stomach to the esophagus. The food and acid causes the burning feeling of heartburn. As your baby gets bigger, the uterus pushes on the stomach making heartburn more common in later pregnancy.
What might help:
- Eat several small meals instead of three large meals — eat slowly.
- Drink fluids between meals — not with meals.
- Don't eat greasy and fried foods.
- Avoid citrus fruits or juices and spicy foods.
- Do not eat or drink within a few hours of bedtime.
- Do not lie down right after meals.
Call your doctor if symptoms don't improve after trying these suggestions. Ask your doctor about using an antacid.
Hemorrhoids during pregnancy
Hemorrhoids are swollen and bulging veins in the rectum. They can cause itching, pain, and bleeding. Up to 50 percent of pregnant women get hemorrhoids. Hemorrhoids are common during pregnancy for many reasons. During pregnancy blood volume increases greatly, which can cause veins to enlarge. The expanding uterus also puts pressure on the veins in the rectum. Plus, constipation can worsen hemorrhoids. Hemorrhoids usually improve after delivery.
What might help:
- Drink lots of fluids.
- Eat fiber-rich foods, like whole grains, raw or cooked leafy green vegetables, and fruits.
- Try not to strain with bowel movements.
- Talk to your doctor about using products such as witch hazel to soothe hemorrhoids.
Itching
About 20 percent of pregnant women feel itchy during pregnancy. Usually women feel itchy in the abdomen. But red, itchy palms and soles of the feet are also common complaints. Pregnancy hormones and stretching skin are probably to blame for most of your discomfort. Usually the itchy feeling goes away after delivery.
What might help:
- Use gentle soaps and moisturizing creams.
- Avoid hot showers and baths.
- Avoid itchy fabrics.
Call your doctor if symptoms don't improve after a week of self-care.
Leg cramps
At different times during your pregnancy, you might have sudden muscle spasms in your legs or feet. They usually occur at night. This is due to a change in the way your body processes calcium.
What might help:
- Gently stretch muscles.
- Get mild exercise.
- For sudden cramps, flex your foot forward.
- Eat calcium-rich foods.
- Ask your doctor about magnesium supplements.
Morning sickness
In the first trimester hormone changes can cause nausea and vomiting. This is called "morning sickness," although it can occur at any time of day. Morning sickness usually tapers off by the second trimester.
What might help:
- Eat several small meals instead of three large meals to keep your stomach from being empty.
- Don't lie down after meals.
- Eat dry toast, saltines, or dry cereals before getting out of bed in the morning.
- Eat bland foods that are low in fat and easy to digest, such as cereal, rice, and bananas.
- Sip on water, weak tea, or clear soft drinks. Or eat ice chips.
- Avoid smells that upset your stomach.
Call your doctor if you have flu-like symptoms, which may signal a more serious condition.
Call your doctor if you have severe, constant nausea and/or vomiting several times every day.
Nasal problems
Nosebleeds and nasal stuffiness are common during pregnancy. They are caused by the increased amount of blood in your body and hormones acting on the tissues of your nose.
What might help:
- Blow your nose gently.
- Drink fluids and use a cool mist humidifier.
- To stop a nosebleed, squeeze your nose between your thumb and forefinger for a few minutes.
Call your doctor if nosebleeds are frequent and do not stop after a few minutes.
Numb or tingling hands
Feelings of swelling, tingling, and numbness in fingers and hands, called carpal tunnel syndrome, can occur during pregnancy. These symptoms are due to swelling of tissues in the narrow passages in your wrists, and they should disappear after delivery.
What might help:
- Take frequent breaks to rest hands.
- Ask your doctor about fitting you for a splint to keep wrists straight.
Stretch marks, skin changes
Stretch marks are red, pink, or brown streaks on the skin. Most often they appear on the thighs, buttocks, abdomen, and breasts. These scars are caused by the stretching of the skin, and usually appear in the second half of pregnancy.
Some women notice other skin changes during pregnancy. For many women, the nipples become darker and browner during pregnancy. Many pregnant women also develop a dark line (called the linea nigra) on the skin that runs from the belly button down to the pubic hairline. Patches of darker skin usually over the cheeks, forehead, nose, or upper lip also are common. Patches often match on both sides of the face. These spots are called melasma or chloasma and are more common in darker-skinned women.
What might help:
- Be patient — stretch marks and other changes usually fade after delivery.
Swelling
Many women develop mild swelling in the face, hands, or ankles at some point in their pregnancies. As the due date approaches, swelling often becomes more noticeable.
What might help:
- Drink 8 to 10 glasses of fluids daily.
- Don't drink caffeine or eat salty foods.
- Rest and elevate your feet.
- Ask your doctor about support hose.
Call your doctor if your hands or feet swell suddenly or you rapidly gain weight — it may be preeclampsia.
Urinary frequency and leaking
Temporary bladder control problems are common in pregnancy. Your unborn baby pushes down on the bladder, urethra, and pelvic floor muscles. This pressure can lead to more frequent need to urinate, as well as leaking of urine when sneezing, coughing, or laughing.
What might help:
- Take frequent bathroom breaks.
- Drink plenty of fluids to avoid dehydration.
- Do Kegel exercises to tone pelvic muscles.
Call your doctor if you experience burning along with frequency of urination — it may be an infection.
Varicose veins
During pregnancy, blood volume increases greatly. This can cause veins to enlarge. Plus, pressure on the large veins behind the uterus causes the blood to slow in its return to the heart. For these reasons, varicose veins in the legs and anus (hemorrhoids) are more common in pregnancy.
Varicose veins look like swollen veins raised above the surface of the skin. They can be twisted or bulging and are dark purple or blue in color. They are found most often on the backs of the calves or on the inside of the leg.
What might help:
- Avoid tight knee-highs.
- Sit with your legs and feet raised.