Pregnancy Guide
A clear, reassuring guide to baby development, common body changes, useful prenatal milestones, and practical next steps from weeks 1 to 40.
Pregnancy week by week brings new questions, new milestones, and often new symptoms. This guide explains what commonly happens during each week, while recognizing that every pregnancy follows its own timeline. Your prenatal care professional is the right person to interpret symptoms, test results, and recommendations for your individual health.
Pregnancy Week by Week at a Glance
| Stage | Weeks | What is happening | Helpful focus |
|---|---|---|---|
| First trimester | 1 to 13 | Conception, implantation, and early organ development | Confirm care, review medicines, and manage early symptoms |
| Second trimester | 14 to 27 | Rapid growth, movement, and developing senses | Attend recommended screening and notice movement patterns |
| Third trimester | 28 to 40 | Growth, brain and lung maturation, and preparation for birth | Prepare for labor, postpartum support, and newborn care |
First Trimester: Weeks 1 to 13
The first trimester includes the dating weeks before conception and the earliest stages of development. Fatigue, breast tenderness, nausea, food aversions, and frequent urination are common, but having few symptoms can also be normal.
Weeks 1 and 2
Pregnancy dating begins on the first day of your last menstrual period, so you are not yet pregnant during most of these two weeks. Your body is preparing to release an egg. If you are planning pregnancy, this is a useful time to review medicines, supplements, alcohol, smoking, and health conditions with a qualified professional.
Week 3
Fertilization may occur and the fertilized egg begins dividing as it travels toward the uterus. Most people do not notice a clear change yet. Continue ordinary healthy routines and avoid relying on symptoms alone to confirm pregnancy.
Week 4
Implantation usually occurs around this stage and pregnancy hormones begin rising. A missed period may prompt a home pregnancy test, although testing too early can produce a negative result. Mild cramping can occur, but significant pain or bleeding deserves medical advice.
Week 5
The early foundations of the brain, spinal cord, heart, and other organs are forming. Fatigue, nausea, smell sensitivity, and breast soreness may begin or intensify. Arrange prenatal care and ask which prenatal vitamin is appropriate for you.
Week 6
Rapid development continues and early cardiac activity may sometimes be visible on ultrasound, depending on exact dating and the type of scan. Nausea can occur at any time of day. Small, frequent meals and regular fluids help some people, but persistent vomiting needs professional advice.
Week 7
The brain and facial structures are developing quickly, while small limb buds continue to grow. Hormonal changes may bring bloating, mood changes, or food aversions. Rest when possible and keep a short list of questions for your first prenatal appointment.
Week 8
Major body systems are taking shape, although they still have a long period of growth ahead. You may notice clothing feels tighter even without a visible bump. Check with your care team before taking over the counter medicines or herbal products.
Week 9
Small muscles are developing and early movement is beginning, but it is far too subtle to feel. Symptoms often remain strong at this point. Hydration, sleep, and realistic expectations can make daily life more manageable.
Week 10
The developing baby is now generally described as a fetus rather than an embryo. Fingers, toes, and facial features are becoming more defined. Prenatal testing options vary by country, medical history, and personal preference, so discuss timing with your clinician.
Week 11
Growth continues rapidly and the head still makes up a large proportion of the body. Some people remain very nauseated, while others begin to feel a gradual improvement. Both patterns can occur in healthy pregnancies.
Week 12
Many internal structures are formed and will continue maturing throughout pregnancy. The uterus is beginning to rise, although a bump may or may not be visible. Do not compare your shape or symptoms with another person’s pregnancy.
Week 13
The transition toward the second trimester is close. Energy and appetite may begin to return, but symptoms do not follow a fixed calendar. Review any screening results and ask what appointments or tests are expected next.
Second Trimester: Weeks 14 to 27
For many people, the second trimester feels more comfortable than the first. The baby grows quickly, movement becomes noticeable, and an anatomy ultrasound is often offered around the middle of pregnancy.
Week 14
Facial muscles and body movements are becoming more coordinated. Early symptoms may ease, although headaches, nasal congestion, or round ligament discomfort can appear. Gentle movement and regular meals may support comfort if your clinician has not advised restrictions.
Week 15
Bones and muscles continue developing, and the baby is becoming more active. You probably will not feel every movement yet. A growing abdomen can change posture, so comfortable footwear and supportive sitting positions may help.
Week 16
Some people, especially those who have been pregnant before, notice the first light fluttering movements around this stage. Others feel nothing for several more weeks. The timing depends on placental position, body anatomy, and individual awareness.
Week 17
The skeleton continues to harden and body fat will gradually begin accumulating. Your center of gravity may start to change. Move carefully when standing and discuss persistent dizziness or fainting with your care team.
Week 18
The baby can make increasingly purposeful movements and developing ears are moving into position. An anatomy scan may be scheduled during the coming weeks. This scan examines growth and major structures but cannot guarantee that every condition will be detected.
Week 19
Protective coatings are developing on the skin, and the senses continue maturing. You may notice stretching sensations, leg cramps, or skin changes. Ask your clinician about any symptom that is severe, sudden, or persistent.
Week 20
You are around the midpoint of a forty week pregnancy. Movement may feel like bubbles, flutters, or gentle taps. The anatomy scan commonly takes place near this time, though exact scheduling varies.
Week 21
Movement is becoming stronger and swallowing practice continues. Appetite may increase as growth accelerates. Focus on varied foods rather than perfection and follow individualized nutrition advice when you have anemia, diabetes, allergies, or another condition.
Week 22
Facial features look more defined and the lungs continue their long maturation process. Back discomfort can increase as posture changes. Short activity breaks and supported sleep positions may improve comfort.
Week 23
The baby is responding more to sound and movement. Braxton Hicks tightening can occur, but painful, regular contractions or concerns about preterm labor should be assessed promptly. Learn how your maternity service wants you to contact them outside normal hours.
Week 24
Growth and lung development continue, and movement often feels more recognizable. Some care systems offer screening for gestational diabetes around this stage. Attend recommended testing even when you feel well, because some pregnancy conditions have few obvious symptoms.
Week 25
The baby is gaining coordination and may respond to familiar sounds. Heartburn, leg cramps, and interrupted sleep are common. Smaller meals and avoiding lying flat immediately after eating may help with mild heartburn.
Week 26
The eyes are developing further and periods of activity and rest may become noticeable. Your abdomen and ribs can feel crowded. Use the baby’s usual pattern, rather than another person’s experience or a fixed kick number from an unverified source, when discussing movement with your care team.
Week 27
The second trimester is ending. The brain, lungs, and nervous system continue maturing, while the baby steadily gains weight. This is a good time to review birth education, leave plans, and practical support for the early postpartum weeks.
Third Trimester: Weeks 28 to 40
The third trimester brings faster weight gain, stronger movement, and increasing physical demands. Prenatal visits often become more frequent as your due date approaches.
Week 28
The baby can open and close the eyes and is developing more regular sleep and activity cycles. Movement patterns matter from this stage onward. Contact your maternity team promptly if movements are clearly reduced or different from what is usual for your baby.
Week 29
Muscles and lungs keep maturing, while the brain develops rapidly. Shortness of breath, constipation, and trouble sleeping can become more noticeable. Mention new or worsening symptoms rather than assuming every discomfort is normal.
Week 30
The baby continues adding body fat and practicing breathing movements. You may feel pressure under the ribs or frequent urination. Plan brief rest periods and keep essential phone numbers easy to find.
Week 31
Most major development now centers on growth and maturation. Strong rolls and stretches may replace sharper kicks as space becomes tighter. Movement should still continue, even though the way it feels can change.
Week 32
The baby may begin settling into a head down position, but there is still time to change position. Prepare a practical birth bag list and discuss pain relief, support people, and feeding preferences without treating the plan as a rigid contract.
Week 33
The immune system and lungs continue developing, while bones become stronger. Swelling of the feet and ankles can be common, but sudden swelling of the face or hands, severe headache, or vision changes require prompt medical assessment.
Week 34
The baby continues practicing breathing and gaining weight. Fatigue often returns as sleep becomes more difficult. Confirm where to go and whom to call if labor begins or your waters break.
Week 35
Space is limited, but regular movement remains important. Pelvic pressure and more frequent urination may increase if the baby moves lower. Review newborn essentials and prioritize a safe sleep space over nonessential purchases.
Week 36
Appointments may become more frequent and your care team may discuss the baby’s position and group B strep testing, depending on local guidance. Practice the route to your chosen birth setting and finalize support for other children or pets.
Week 37
This stage is considered early term in many clinical systems. The baby is still developing and gaining weight. Irregular tightenings may increase, but contact your care team when contractions become regular, your waters break, bleeding occurs, or you are unsure what you are feeling.
Week 38
The baby continues preparing for birth and may sit lower in the pelvis. Sleep can be fragmented and anticipation can feel intense. Keep plans flexible and make rest, hydration, and practical support the priority.
Week 39
Thirty nine weeks marks the beginning of full term in commonly used definitions. Labor may start gradually with contractions, backache, a show, or ruptured membranes, but experiences vary widely. Follow your maternity team’s instructions about when to call or travel in.
Week 40
Your estimated due date is a guide, not an expiry date, and many babies arrive before or after it. Continue monitoring normal movement and attending appointments. Your clinician will explain local options for additional monitoring or induction if pregnancy continues beyond the due date.
What to Do After You Learn You Are Pregnant
- Arrange prenatal care. Early care helps review health conditions, medicines, screening options, and individual risk.
- Ask about a prenatal vitamin. Folic acid is especially important before and during early pregnancy, but the right supplement and dose depend on your circumstances.
- Review medicines and supplements. Do not stop a prescribed medicine suddenly without professional guidance.
- Know how to get urgent advice. Save the number for your maternity service and learn where to seek help outside normal hours.
- Choose reliable information. Prefer recognized health organizations and advice tailored by your own clinician.
Frequently Asked Questions
Why does pregnancy start before conception?
The exact day of conception is often uncertain, while the first day of the last menstrual period is easier to identify. Health professionals therefore use that date to calculate gestational age and an estimated due date.
How many weeks are in each trimester?
Definitions vary slightly. A common approach places the first trimester through week 13, the second from weeks 14 to 27, and the third from week 28 through birth. Your care team may use slightly different boundaries without changing your actual due date.
Is it normal to have different symptoms from a week by week guide?
Yes. Symptoms can differ between people and between pregnancies. A guide describes common patterns, not a checklist that every healthy pregnancy must follow.
When can I usually feel the baby move?
Many people first notice movement between roughly 16 and 24 weeks, sometimes earlier in a later pregnancy. Placental position and other factors affect timing. Ask your maternity team if you have not felt movement by the time they expect for your pregnancy.
Should I worry if the due date changes?
Dating can change after an early ultrasound if measurements differ from the date estimated from your last period. Your clinician will explain which date should be used for future appointments.
Trusted Sources
- NHS week by week pregnancy guide
- Office on Women’s Health stages of pregnancy
- American College of Obstetricians and Gynecologists healthy eating during pregnancy
- NHS pregnancy, antenatal care, symptoms, and complications
Related Pregnancy Guides
Pregnancy Guide | Due Date Calculator | Pregnancy Warning Signs | Labor and Delivery