Pregnancy lasts ~40 weeks and is divided into 3 trimesters. Your body will go through a variety of changes throughout your pregnancy. You may notice different symptoms as you move along each trimester

Pregnancy Overview

Reviewed: September 2, 2014

The events that lead to pregnancy begin with conception, in which the sperm penetrates the egg produced by an ovary.

Pregnancy lasts about 40 weeks, counting from the first day of your last normal period. The 40 weeks are divided into 3 trimesters.

  • First Trimester (Week 1-Week 12)
  • Second Trimester (Week 13-Week 28)
  • Third Trimester (Week 29-Week 40)

Your baby develops throughout the pregnancy.

  • At 8 weeks, all major organs and external body structures have begun to form. Your baby's heart beats with a regular rhythm.
  • At 16 weeks, and in some cases, by 12 weeks, the sex of the baby can be determined. At this point, muscle tissue and bone continue to form, creating a more complete skeleton.
  • At 20 weeks, your baby is more active and you may begin to start feeling movement.
  • At 24 weeks, footprints and fingerprints have formed. In addition, your baby sleeps and wakes regularly.
  • At 32 weeks, the bones are soft and yet almost fully formed, and the eyes can open and close.
  • 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.

It is very important you have regular visits with your healthcare provider.  This consistent care can help keep you and your baby healthy.

It is also very important you live a healthy lifestyle like eating a healthy diet. This will ensure your baby gets the right amount of nutrients. There are also many other things you should be aware of to keep you and your baby healthy and safe throughout the pregnancy.

Pregnancy Symptoms

During pregnancy, your body undergoes many changes. The symptoms and changes you make experience throughout your pregnancy are listed by the trimester.

First Trimester (Week 1-Week 12)

  • Extreme fatigue
  • Tender and swollen breasts
  • Protruding nipples
  • Nausea
  • Food cravings
  • Distaste for certain foods
  • Mood swings
  • Constipation
  • Need to urinate more frequently
  • Headache
  • Heartburn
  • Weight gain or loss

Second Trimester (Week 13-Week 28)

During your second trimester, you may notice that your nausea and fatigue are not as prevalent, but you may notice more noticeable changes happening to your body.

  • Body aches (back, stomach, groin, or thigh pain)
  • Stretch marks on your stomach, breasts, thighs, or buttocks
  • Darkening of the skin around your nipples
  • A line on the skin that runs from the belly button to the pubic hairline
  • Patches of darker skin on face
  • Numbing or tingling of hands
  • Itching on stomach, palms, and soles of feet
  • Swelling of ankles, fingers, and face

Third Trimester (Week 29-Week 40)

  • Shortness of breath
  • Having to urinate more often
  • Heartburn
  • Swelling of ankles, fingers, and face
  • Hemorrhoids
  • Tender breasts (may leak with pre-milk)
  • Protruding belly button
  • Trouble sleeping
  • Contractions (can be real or false labor)

As you get closer to your due date, your cervix becomes thinner and softer. This is normal as this change facilitates the birth canal to open during the birthing process.

Pregnancy Causes

The events that lead to pregnancy begin with conception. Conception occurs when the sperm penetrates the egg produced by an ovary.

The zygote (fertilized egg) then travels through the woman's fallopian tube to the uterus, where it implants itself in the uterine wall.

The zygote is made up of a cluster of cells formed from the egg and sperm. These cells form the fetus and the placenta.

Pregnancy Diagnosis

Prenatal Tests

Your doctor may order the following tests at your first prenatal check up:

  • Your blood type and Rh factor
  • Anemia
  • Infections, such as toxoplasmosis and sexually transmitted infections (STIs) which may include hepatitis B, syphilis, chlamydia, and HIV
  • Signs that you are immune to rubella (German measles) and chicken pox

Your doctor may also order screening tests to detect the risk for possible health problems. Some screenings mau include:

  • First trimester screen- Screening done at 11-14 weeks to detect risk for chromosome abnormalities
  • Glucose Challenge screening- -Screening done at 26-28 weeks to determine risk for gestational diabetes.
  • Maternal serum screen (also called quad screen, triple test, triple screen, multiple marker screen, or AFP)- screening done at 15-20 weeks to detect risk for chromosome abnormalities.

Based on screening test results, your doctor may recommend diagnostic tests to confirm or rule out health problems. Some diagnostic tests may include:

  • Amniocentesis - Performed at 14-20 weeks, can detect certain birth defects such as Down syndrome, cystic fibrosis, and spina bifida.
  • Chorionic villus sampling (CVS)- Performed at 10-13 weeks, can detect Down syndrome and cystic fibrosis.
  • Glucose tolerance test- Performed at 26-28 weeks can diagnose gestational diabetes.

Other Prenatal Tests may include:

  • Biophysical profile (BPP)- performed during the third trimester to monitor the overall health of your baby
  • Group B streptococcus infection- performed at 36-37 weeks, can look for bacteria that can cause an infection in your newborn.
  • Nonstress test (NST)- Performed after 28 weeks, looks to see if your baby is getting enough oxygen.
  • Ultrasound exam- can be performed at any time during the pregnancy. An ultrasound is usually done between 18-20 weeks to look for proper growth of the fetus, to ensure there are no problems with the baby's organs, and can identify the sex of the baby.
  • Urine test- used to detect problems such as urinary tract infections, diabetes, and preeclampsia.

Living With Pregnancy

It is very important you have regular visits with your healthcare provider. These prenatal care visits are very important for you and your baby. This consistent care can help keep you and your baby healthy, identify an problems if they occur, and as a result prevent problems during delivery. Typically, routine checkups occur:

  • Once each month for weeks four through 28
  • Twice a month for weeks 28 through 36
  • Weekly for weeks 36 to birth

Women with high-risk pregnancies will need to see their doctor more often.

If you have been pregnant before, you might feel different this time around. Just as each woman is different, so is each pregnancy.


Eating a healthy diet is more important now than ever. You will require more protein, iron, calcium, and folic acid than you did before pregnancy. You also need more calories. But "eating for two" does not mean you can eat twice as much. Instead it means the foods you eat are the main source of nutrients for your baby.

Weight Gain

The amount of weight you should gain during pregnancy will depend on your body mass index (BMI) before you became pregnant. These guidelines are based on the Institute of Medicine:

  • If you were at a normal weight before pregnancy, you should gain about 25 to 30 pounds.
  • If you were underweight before pregnancy, you should gain between 28 and 40 pounds.
  • If you were overweight before pregnancy, you should gain between 15 and 25 pounds.
  • If you were obese before pregnancy, you should gain between 11 and 20 pounds.

Ask your doctor about how much weight gain during pregnancy is healthy for you.

You should gain weight at a gradual rate during your pregnancy, with most of the weight gained in the last trimester. Doctors typically suggest women gain weight at the following rate:

  • 2 to 4 pounds total during the first trimester
  • 3 to 4 pounds per month for the second and third trimesters

Your calorie needs will depend on your weight gain goals. Most women need 300 calories a day more during at least the last six months of pregnancy than they do before they became pregnant. With that being said, you should not restrict your diet either.

Eating Healthy

Be sure to eat a healthy diet. A pregnant women needs more vitamins, minerals, and nutrients than she did before pregnancy. Make sure to drink plenty of water. When you are pregnant, your body needs even more water to stay hydrated and support your baby. The Institute of Medicine recommends pregnant women drink about 10 cups of fluids daily. Water, juices, coffee, tea, and soft drinks all count toward your fluid needs.

In addition, ask your doctor about taking a prenatal vitamin and mineral supplement every day to be sure you are getting enough of the nutrients your baby needs.

  • Caffeine- Moderate amounts of caffeine appear to be safe during pregnancy. Moderate means less than 200 mg of caffeine per day, which is the amount in about 12 ounces of coffee.
  • Fish consumption-Fish can be an important part of a healthy diet. Women who are or may become pregnant and nursing mothers need 12 ounces of fish per week to get the health benefits. However, some pregnant and nursing women do not eat any fish, because they worry about mercury in seafood. Shrimp, crab, salmon, and tilapia are types of fish that have little or no mercury and can be consumed.

Cravings- Many women have strong desires for specific foods during pregnancy. However, some women crave nonfood items such as clay, ice, laundry starch, or cornstarch. The desire to eat nonfood items is called pica. Eating nonfood items can be harmful to your pregnancy. If you have any of these urges, talk to your doctor.


For most healthy pregnant women who do not have any pregnancy-related problems, exercise is safe. Talk to your doctor about starting a fitness activity. Your doctor will let you know what type of exercise and how much exercise would be best in your situation.

Low-impact activities at a moderate level such as walking, swimming, dancing, cycling, and low-impact aerobics are comfortable and enjoyable for many pregnant women.

Some higher intensity sports are safe for some pregnant women who were already doing them before becoming pregnant. If this is the case, you may continue with your doctor's permission.

Kegal exercises

Working out your kegal muscles will help during delivery as well as recover after birth. Pelvic floor muscles are the are the same ones used to stop the flow of urine.

To perform Kegal exercises:

  1. Tighten the pelvic floor muscles for a count of three, then relax for a count of three.
  2. Repeat 10 to 15 times, three times a day.
  3. Start Kegel exercises lying down. This is the easiest position. When your muscles get stronger, you can do Kegel exercises sitting or standing as you like.

Taking medications while pregnant

The medications you take while pregnant, including over-the-counter, herbal, prescription medications, and supplements, can reach your baby. With that being said, some medications are known to cause your baby harm, including fetal defects. Talk to your doctor about all the medications you take. He/she will determine the best course of action in terms of what medications you will continue to take during pregnancy. Do not stop any medication without asking your doctor first. Not taking a medication that you need may cause you and your baby harm.

Having Sex- Unless your doctor tells you otherwise, sex is safe.


Talk to your doctor before traveling.

  • Avoid sitting for long periods during car or air travel. Prolonged sitting can affect the blood flow in your legs. Try to limit driving to no more than 5 or 6 hours each day and take frequent breaks to stretch your legs. Stand up, and move your legs often during air travel. Wearing support pantyhose also can help blood flow.
  • Occasional air travel is safe for most pregnant women, and most airlines will allow women to fly up to 36 weeks of pregnancy.

Smoking, Alcohol, and Illegal Drugs

  • Alcohol- When pregnant, avoid alcohol. here is no known safe amount of alcohol a woman can drink while pregnant.
  • Smoking-Smoking cigarettes is very harmful to your health and could also affect the health of your baby. Ask your doctor about quitting smoking.
  • Illegal drugs-Using illegal drugs during pregnancy is very dangerous. Talk to your doctor if you use drugs.


Pregnancy Treatments

Your doctor will typically prescribe a prenatal vitamin and mineral supplement to be taken every day to be sure you are getting enough of the nutrients your baby needs.

During the 9 months of pregnancy, your body will go through many changes that may cause discomfort such as body aches/headaches, constipation, heartburn/indigestion, stretch marks, morning sickness, and hemorrhoids. Tell your doctor if start to experience any of these conditions associated with pregnancy. He/she may need to prescribe medications if non-pharmacological approaches are not effective.

Body aches/Headaches: Tylenol (acetaminophen) is the recommended over the counter medication to manage pain if you have a headache or body aches.

Constipation: If increasing fiber and liquid intake does not help your constipation, your doctor may recommend a stool softener such as docusate (Colace) or an osmotic laxatives such as polyethylene glycol (MiraLax).

Heartburn and indigestion: Your doctor may recommend antacids containing aluminum, calcium, and magnesium to help manage your heartburn and indigestion. if these are not effective, your doctor may recommend histamine-2 receptor antagonists such as ranitidine (Zantac) or famotidine (Pepcid) or prescribe proton pump inhibitors (PPIs) such as omeprazole (Prilosec), pantoprazole (Protonix), esomeprazole (Nexium), or lansoprazole (Prevacid).

Stretch Marks: Although there is no scientific evidence to prove any over the counter stretch mark prevention lotions work, some users have reported good results with products like Reviva, cocoa butter, and Vitamin E oil.  Rubbing lotion on your belly each evening may prevent itching and may help moisturize and improve your skin quality. If your stretch marks really bother you, talk to your physician or pharmacist.Your doctor can prescribe a topical medication like Retin-A to reduce the appearance of the scars post pregnancy.

Morning Sickness (Nausea):

  • Pyridoxine (vitamin B6) which is considered Pregnancy Category A can be given to help manage nausea and vomiting.
  • Other alternatives include Bonine (meclizine), Dramamine (dimenhydrinate), and Benadryl (diphenhydramine). These medications are classified as Pregnancy Category B and are reserved for those women who have severe nausea/v vomiting that is not responsive to lifestyle changes.
  • Diclegis (doxylamine succinate and pyridoxine hydrochloride) is another option your doctor can prescribe for you. Diclegis (doxylamine succinate and pyridoxine hydrochloride) falls under pregnancy category A. Diclegis (doxylamine succinate and pyridoxine hydrochloride) is intended for use in pregnant women who have not responded to lifestyle changes.
  • Some doctors may prescribe Zofran (odansetron) to help manage your nausea. Zofran (odansetron) falls under pregnancy category B. However, based on the data available today, Zofran (ondansetron) use cannot be assumed to be safe during pregnancy.

Hemorrhoids: Hemorrhoids in pregnancy should be treated by increasing fiber content in the diet, administering stool softeners, increasing liquid intake, and training in toilet habits. If treatment is needed, your doctor may recommend a product called Tucks Medicated Pads. Your doctor may recommend topical medications with analgesics and/or anti-inflammatory effects. However, the safety of any of them in pregnancy has not been properly documented.

Pregnancy Prognosis

Sometimes problems can arise during pregnancy even in healthy women.

Some health problems may include:

  • Anemia- Lower than normal number of red blood cells
  • Depression- Extreme sadness during pregnancy or after birth (postpartum)
  • Ectopic pregnancy- Happens when a fertilized egg implants outside of the uterus, usually in the fallopian tube
  • Fetal problem-Unborn baby has an issue such as poor growth or heart problems
  • Gestational diabetes- High blood sugars during pregnancy
  • High blood pressure - High blood pressure that occurs after 20 weeks and goes away after delivery
  • Hyperemesis gravidarum- Severe and persistent nausea and vomiting during pregnancy (more extreme case of morning sickness)
  • Miscarriage- Loss of pregnancy before 20 weeks due to a natural cause
  • Placenta previa – Placenta covers part or entire opening of cervix inside of the uterus
  • Placental abruption – Placenta separates from uterine wall before delivery, which can mean the fetus does not get enough oxygen
  • Preeclampsia- Causes high blood pressure after 20 weeks and causes problems with kidneys and other organs
  • Preterm labor- Going into labor before 37 weeks of pregnancy
  • Infections
    • Urinary Tract Infections- Bacterial infection in urinary tract. You will need to be treated with antibiotics to prevent complications
    • Yeast Infection- An infection caused by an overgrowth of bacteria normally found in the vagina. They do not threaten the health of your baby. But they can be uncomfortable. You will be treated with vaginal creams or suppositories.