What You Need to Know About Pregnancy

Pregnancy can be one of the most exciting and rewarding events. Creating a new life is an intricate process that causes many changes in a person’s body.

Learn more about what to expect during the nine months that precede birth—from conception to delivery.

pregnant woman sitting in grass

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Conception is the joining of a sperm and egg, also known as fertilization. In most cases, conception occurs in a person’s fallopian tube in the hours or days following sexual intercourse. However, in cases of assisted reproduction, particularly in vitro fertilization, conception can occur in a lab. 


Conception may happen close to when a couple has sexual intercourse, but it can also occur days after intercourse. That’s because an egg can be fertilized for a 12- to 24-hour window, and sperm can survive in the female reproductive tract for up to five days.

Conception marks the first step toward pregnancy—the sperm and egg have joined together, creating what is known as a zygote. In the coming days, the single-cell zygote transforms into a multi-celled embryo.


In order to facilitate pregnancy, an embryo must successfully move from the fallopian tubes and implant in the uterus, where it will continue to develop into a fetus and eventually an infant.

Bleeding During Implantation

Bleeding may occur during implantation, which is a normal symptom that doesn’t require any medical attention.

Approximately 15% to 25% of those who become pregnant will experience bleeding in the first trimester.

Since three types of bleeding related to your cycle and/or pregnancy can occur, it can be confusing to determine the cause of bleeding. The types of bleeding include:

  • Implantation bleeding: When a fertilized egg attaches itself to the uterine lining (endometrium)
  • Ovulation bleeding: Light bleeding or spotting that occurs when an egg is released from the ovary
  • Period bleeding: If a fertilized egg does not implant in the wall of your uterus after ovulation, the lining sheds.

The timing of bleeding can help provide clues about the bleeding cause.

Timing of Bleeding
Implantation Bleeding 20 to 24 days
Ovulation Bleeding 14 days
Period Bleeding 28 days
*Based on a 28-day cycle

Early Symptoms

While a missed period and implantation bleeding are obvious early signs of pregnancy, there are several other symptoms to watch for if you’re trying to conceive, including:

  • Nausea and vomiting
  • Fatigue
  • Breast tenderness
  • Frequent urination
  • Mood swings
  • Appetite changes
  • Metallic taste
  • Headaches
  • Cramping
  • Constipation
  • Nasal congestion

Symptoms vary from person to person—including those who experience no early signs of pregnancy.

How to Be Sure You’re Pregnant

To confirm you’re pregnant, you can:

  • Take an at-home pregnancy test: When used correctly, home pregnancy tests are 97% to 99% accurate.
  • Get a blood test at your healthcare provider’s office: Pregnancy blood tests are 99% accurate and are often used to confirm a positive at-home pregnancy test.

Pregnancy has a range of symptoms, but most don’t develop all at once. When they surface or subside may depend on the stage of pregnancy.

Healthcare Provider’s Visits

Prenatal care is critical during pregnancy.

If you conceive naturally, your first healthcare provider visit usually happens toward the end of your first trimester. If you conceive through in vitro fertilization (IVF), you may see your healthcare provider sooner.

Either way, it’s best that the first major checkup happens during the first trimester (up to 13 weeks of pregnancy). It usually occurs between eight to 12 weeks.

During this visit, your healthcare provider will:

  • Go over your health history
  • Perform a physical and pelvic exam
  • Give an overview for treatment during your pregnancy

Be sure to prepare a list of questions to ask your healthcare provider so you don’t forget.

Most people will also get their first ultrasound of the fetus to check the fetus’s heartbeat and anatomy, and your healthcare provider will calculate how many weeks pregnant you are and set a due date for the baby.

Timing of Healthcare Provider’s Visits

For most people, barring any special circumstances, pregnant people see their healthcare provider:

  • Every four weeks until they are 28 weeks pregnant
  • Every two to three weeks between 28 to 36 weeks pregnant
  • Weekly from 36 weeks pregnant until delivery


Pregnancy is 40 weeks long, though some people deliver before or after that timeframe. Pregnancy is divided into three trimesters—each 13 weeks long and encompassing different phases of the baby’s development that ends in birth.

First Trimester (Weeks 1 to 13)

During the first trimester, your body undergoes extensive changes that set the stage for your growing baby. Hormonal changes affect nearly every organ system in your body, which can trigger a variety of early pregnancy symptoms (listed above) even in the initial weeks of pregnancy.

While you may not see much of a difference on the outside, a lot of development happens to your baby even in the first weeks of pregnancy.

By eight weeks your baby’s:

  • Arms and legs have grown longer
  • Hands and feet begin to form and look like little paddles
  • Brain continues to grow
  • Lungs start to form
  • Heart will be beating regularly
Pregnancy: Week 8

Second Trimester (Weeks 14 to 27)

Many people report feeling their best during the second trimester. Morning sickness and fatigue often subside so they feel much more energetic and can enjoy food again. Still, other new, more noticeable changes to your body occur.

Your abdomen and uterus will expand as the baby continues to grow. During the second trimester, a true “baby bump” becomes noticeable.

Feeling Baby Kicks

During this trimester you will feel your baby begin to move. There is a broad range of when the first detection of movement can be felt, ranging from 16 to 22 weeks.

As your body changes to make room for your growing baby, you may experience:

  • Body aches, such as back, abdomen, groin, or thigh pain (discuss these symptoms with your healthcare provider)
  • 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 (linea nigra)
  • Patches of darker skin on your face (mask of pregnancy)
  • Numb or tingling hands (if you notice this, call your healthcare provider)
  • Itching on the abdomen, palms, and soles of the feet (sometimes itching in pregnancy can have causes that could potentially be harmful to the pregnancy, so let your healthcare provider know about this symptom)
  • Swelling of the ankles, fingers, and face (if you notice this, call your healthcare provider)

By 20 weeks, your baby:

  • Can hear
  • Is more active and continues to move and float around
  • Can swallow
Pregnancy: Week 20

Third Trimester (Weeks 28 to 40)

Some of the same discomforts experienced in your second trimester continue into the third. You will likely have additional symptoms, too.

At this stage, you may feel a little more short of breath, which you should still mention to your healthcare provider to make sure it’s appropriate for your pregnancy and not excessive. Trips to the bathroom also increase because the baby is getting bigger and is putting more pressure on your bladder and other organs.

Some other new body changes you might notice in the third trimester include:

  • Heartburn
  • Swelling of the ankles, fingers, and face
  • Hemorrhoids
  • Sore breasts, which may leak colostrum, a precursor to breast milk
  • Your belly button may stick out
  • Insomnia
  • The baby “dropping” lower in the uterus
  • Contractions, which can be a sign of real or false labor (Braxton Hicks contractions; if you experience contractions more than a few times per hour before 37 weeks, call your healthcare provider)

As your due date gets closer, your cervix becomes thinner and softer (effacement). This is a natural process that helps the birth canal to open during the birthing process. In most cases, the baby will also move into a head-down position by the end of the last trimester.

Premature Birth

Babies born prematurely (before 37 weeks) have a higher chance of complications.

At 39 weeks, babies are considered full term. This means all of the baby’s organs are ready to function on their own outside of the womb.

By 37 weeks, your baby:

  • Weighs about 5 1/2 pounds
  • Keeps gaining weight, but will probably not get much longer
  • Has less wrinkled skin as fat forms under the skin
  • Has definite sleeping patterns
  • Has heart and blood vessels fully developed
  • Has muscles and bones fully developed
Pregnancy: Week 37

Risks and Complications

While pregnancy is often an exciting time, it’s important to be aware of potential risks so you can seek care as soon as possible.

If you are considered at high risk for pregnancy complications, you may be referred to a perinatologist (a maternal fetal medicine high-risk specialist) to partner with your healthcare provider in your care.

Risk factors for pregnancy can include:

  • Existing health conditions: Examples include high blood pressure, diabetes, or being HIV-positive.
  • Being overweight: This increases the risk for high blood pressure, preeclampsia, gestational diabetes, stillbirth, neural tube defects, and cesarean delivery.
  • Multiple births: The risk of complications is higher in those carrying more than one fetus (twins and higher-order multiples). Common complications include preeclampsia, premature labor, and preterm birth.
  • Young or old maternal age: Pregnancy in teens and those age 35 or older increases the risk for preeclampsia and gestational high blood pressure.

Having a high-risk pregnancy puts you at risk for complications, including:

  • Miscarriage
  • Preeclampsia
  • Gestational diabetes
  • Anemia


Miscarriage is when a pregnancy spontaneously ends before 20 weeks. It’s the most common type of pregnancy loss and may happen in 10% to 20% of all diagnosed pregnancies.

Chemical pregnancies happen when a pregnancy ends shortly after implantation, resulting in bleeding that occurs around the time of your period. Someone may not realize that they’ve conceived when a chemical pregnancy occurs. These pregnancy losses may account for 50% to 75% of all miscarriages.

Pregnancy After Miscarriage

Most people (87%) go on to have normal pregnancies and births after having a miscarriage.

Nearly 50% of miscarriages are caused by embryos with a chromosomal abnormality. The risk increases with age. Symptoms include:

  • Progressive heavy bleeding
  • Cramping
  • Abdominal pain
  • Low backache that may range from mild to severe

Note, these symptoms can also occur with an ectopic pregnancy.

Pregnancy Loss Support


Preeclampsia is when a person develops high blood pressure and high levels of protein in their urine during pregnancy. The condition usually resolves after the delivery of the baby.

High blood pressure can jeopardize the health of the mother and the baby during pregnancy.

Preeclampsia can lead to complications such as:

  • Stroke
  • The need to deliver the baby earlier than expected
  • Placental abruption (when the placenta separates from the uterus)
  • Preterm birth
  • Low birth weight in the baby

Lower Your Risk of Preeclampsia

You can lower your risk of preeclampsia by maintaining a healthy weight, exercising, and following a healthy diet before becoming pregnant.

Those who are considered to be at higher risk for developing preeclampsia and its related complications may be advised to take daily low-dose aspirin starting after 12 weeks of pregnancy.

Still, some develop preeclampsia despite taking preventive measures.

Because of potentially serious complications, people with preeclampsia require close monitoring by their healthcare provider.

Gestational Diabetes 

Gestational diabetes is a type of diabetes that develops during pregnancy. Pregnant people are tested for gestational diabetes between 24 and 28 weeks.

Uncontrolled blood sugar can cause complications during the pregnancy for mother and baby including:

  • Extra-large babies: Uncontrolled blood sugar drives up the baby’s blood sugar, too. This can lead to babies growing too big.
  • C-section: Someone whose blood sugar isn’t well controlled has a higher risk of delivery by C-section.
  • Preeclampsia: People with diabetes have high blood pressure more often than those without diabetes.
  • Hypoglycemia (low blood sugar): This is a potentially life-threatening side effect from taking medications to control blood sugar. In many cases, gestational diabetes can be managed through exercise and a healthy diet. However, some people will also require insulin.

Gestational Diabetes and Type 2 Diabetes

Gestational diabetes usually subsides after birth, but having it does raise the risk of developing type 2 diabetes later in life. In fact, half of those who’ve had gestational diabetes will get type 2 at some point.


Iron deficiency is common in pregnancy and is the most common cause of anemia in pregnant people. Anemia happens when the body lacks sufficient amounts of red blood cells, which are needed to carry oxygen through the body.

During pregnancy, the heart has to work harder in order to provide nourishment to the fetus. The body increases its blood volume by 40% to 50% to accomplish this.

When iron levels are low, red blood cells are unable to carry oxygen to the body’s tissues. It is normal to experience mild anemia during pregnancy due to increased blood volume, but severe anemia may put you and your baby at risk of premature delivery and low birth weight.

Symptoms of anemia during pregnancy may include the following:

  • Fatigue
  • Weakness
  • Difficulty concentrating
  • Shortness of breath
  • Pale skin
  • Chest pain
  • Lightheadedness
  • Cold hands and feet
  • Rapid heartbeat

A Word From Verywell

Pregnancy can be one of the most gratifying times in a person’s life. It can also be one of the most challenging with so much to consider. With proper prenatal care and maintaining a healthy lifestyle, you increase your chances of having a healthy baby.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cherie Berkley, MS
Cherie Berkley is an award-winning journalist and multimedia storyteller covering health features for Verywell.