Learn more about what to expect during the nine months that precede birth—from conception to delivery.
Conception
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 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.
Implantation
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.
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.
Nausea and vomitingFatigueBreast tendernessFrequent urinationMood swingsAppetite changesMetallic tasteHeadachesCrampingConstipationNasal congestion
Symptoms vary from person to person—including those who experience no early signs of pregnancy.
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.
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.
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 historyPerform a physical and pelvic examGive 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.
Trimesters
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.
Every four weeks until they are 28 weeks pregnantEvery two to three weeks between 28 to 36 weeks pregnantWeekly from 36 weeks pregnant until delivery
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 longerHands and feet begin to form and look like little paddlesBrain continues to growLungs start to formHeart will be beating regularly
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.
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 hearIs more active and continues to move and float aroundCan swallow
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:
HeartburnSwelling of the ankles, fingers, and faceHemorrhoidsSore breasts, which may leak colostrum, a precursor to breast milkYour belly button may stick outInsomniaThe baby “dropping” lower in the uterusContractions, 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.
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 poundsKeeps gaining weight, but will probably not get much longerHas less wrinkled skin as fat forms under the skinHas definite sleeping patternsHas heart and blood vessels fully developedHas muscles and bones fully developed
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:
MiscarriagePreeclampsiaGestational diabetesAnemia
Miscarriage
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.
Nearly 50% of miscarriages are caused by embryos with a chromosomal abnormality. The risk increases with age. Symptoms include:
Progressive heavy bleedingCrampingAbdominal painLow backache that may range from mild to severe
Note, these symptoms can also occur with an ectopic pregnancy.
Preeclampsia
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.
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High blood pressure can jeopardize the health of the mother and the baby during pregnancy.
Preeclampsia can lead to complications such as:
StrokeThe need to deliver the baby earlier than expectedPlacental abruption (when the placenta separates from the uterus)Preterm birthLow birth weight in the baby
Still, some develop preeclampsia despite taking preventive measures.
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.
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.
Anemia
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:
FatigueWeaknessDifficulty concentratingShortness of breathPale skinChest painLightheadednessCold hands and feetRapid 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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