Pregnancy Symptoms by Week: Trimester-Wise Timeline Guide

Pregnancy symptoms can change from week to week, and every pregnancy is different. Some people notice nausea, tiredness or breast tenderness early on, while others have few or no symptoms during the first few weeks. As pregnancy progresses, hormonal changes and the growing baby can bring new physical changes.

This article explains how pregnancy symptoms may change from conception through each trimester, what you may notice at different stages and which symptoms need prompt medical attention.

Pregnancy is usually dated from the first day of your last menstrual period, so the first two weeks are counted before conception. After fertilisation, the developing embryo travels towards the uterus. Implantation usually occurs about 6 to 12 days after ovulation.

After implantation, the body begins producing human chorionic gonadotropin (hCG), the hormone detected by pregnancy tests. As hCG and other pregnancy hormones increase, some early symptoms may begin to appear.

During the early weeks, you may notice:

• Light spotting
• Mild lower abdominal or pelvic cramping
• Tiredness
• Breast tenderness or sensitivity

These symptoms can be similar to those experienced before a period, and many people do not notice any pregnancy symptoms at this stage.

A missed period is often one of the first noticeable signs of pregnancy. If your period is late and pregnancy is possible, a home pregnancy test can help determine whether you are pregnant.

The first trimester covers weeks 1 to 12. Hormonal changes during this period can cause several symptoms, although their intensity varies from person to person.

Weeks 1 to 4

You may not notice any symptoms during the first few weeks. If symptoms occur, they may include:

• Tiredness
• Breast tenderness or sensitivity
• Mild abdominal cramping
• Light spotting
• Increased sensitivity to smells
• Changes in appetite

A pregnancy test is more likely to give an accurate result after a missed period because hCG levels need time to rise to detectable levels.

Weeks 5 to 8

Pregnancy symptoms often become more noticeable around this time. You may experience:

• Nausea, with or without vomiting
• Tiredness
• Breast tenderness
• Frequent urination
• Food cravings or aversions
• Increased sensitivity to smells
• Mood changes
• Bloating or constipation

Nausea and vomiting can happen at any time of day, despite commonly being called morning sickness.

Weeks 9 to 12

Nausea and tiredness may continue during this period. Some people find that these symptoms begin to improve towards the end of the first trimester, while others continue to experience them for longer.

You may also notice:

• Increased urination
• Breast changes
• Heartburn or indigestion
• Constipation
• Headaches
• Changes in appetite

The presence or absence of symptoms does not by itself indicate how a pregnancy is progressing. Some people have few symptoms and continue to have a healthy pregnancy.

The second trimester covers weeks 13 to 26. For many people, nausea and tiredness improve during this period, while physical changes associated with the growing uterus become more noticeable.

You may experience:

• Fetal movements: Most people first become aware of their baby's movements between about 16 and 24 weeks. If this is your first pregnancy, you may notice them after 20 weeks. Early movements may feel like gentle fluttering, bubbling or swirling.
• Round ligament pain: Stretching of the ligaments supporting the uterus can cause brief pain or a pulling sensation in the lower abdomen or groin, particularly when changing position.
• Heartburn and indigestion: Hormonal changes and the growing uterus can contribute to these symptoms.
• Leg cramps: These can occur during pregnancy, particularly at night.
• Nasal congestion: Hormonal and blood-flow changes can cause swelling inside the nose.
• Skin changes: Stretch marks, darkening of the nipples and linea nigra may become more noticeable.
• Increased vaginal discharge: Normal pregnancy discharge is usually clear or white and should not have a strong unpleasant smell.

Routine antenatal appointments continue during this stage to monitor your health and your baby's development. The detailed ultrasound scan, often called the anomaly scan, is usually offered around 18 to 21 weeks.

The third trimester begins at week 27 and continues until delivery. As the baby grows, physical discomfort and pressure on surrounding organs may become more noticeable.

Common symptoms include:

• Back pain and pelvic discomfort: The growing uterus and changes in the body can place additional strain on the back and pelvis.
• Frequent urination: Pressure from the growing uterus and, later, the baby's position can increase the need to urinate.
• Heartburn: This may continue or become more noticeable as pregnancy progresses.
• Swelling: Mild swelling of the feet and ankles can occur, particularly later in the day.
• Sleep difficulties: Physical discomfort and frequent urination can make it harder to sleep.
• Breathlessness: The growing uterus can make you feel short of breath, particularly later in pregnancy.
• Braxton Hicks contractions: These are irregular tightenings of the uterus that may become more noticeable as pregnancy progresses. They do not usually become progressively stronger or more regular.

Regular contractions that become stronger, longer and closer together may indicate the start of labour.

As you get closer to your due date, you may notice increased pelvic pressure, regular contractions or the passage of a mucus plug, sometimes called a show.

Your waters may also break as labour begins or before contractions start. This may feel like a sudden gush or a continuous leakage of fluid.

Contact your maternity team if you think your waters have broken, particularly if this happens before 37 weeks.

Most pregnancy symptoms are not a cause for concern, but some need prompt medical assessment.

Seek medical attention if you experience:

• Heavy vaginal bleeding
• Severe or persistent abdominal or pelvic pain
• A severe headache, particularly with blurred vision or other visual changes
• Sudden or marked swelling of the face or hands
• Chest pain or sudden difficulty breathing
• Fever or chills
• Pain or burning when passing urine, particularly with fever or back pain
• Leakage of fluid from the vagina before 37 weeks
• Regular contractions before 37 weeks
• A change in your baby's usual movements once you have started feeling them

If your baby's movements become less frequent or change from their usual pattern, contact your maternity unit or healthcare professional promptly. Do not wait until the next day.

Pregnancy can change how your body responds to medicines, so check before taking any medicine or supplement.

• Do not start, stop or change a prescribed medicine without speaking with your doctor.
• Check with your doctor or pharmacist before taking an over-the-counter medicine, supplement or herbal product.
• Take pregnancy supplements such as folic acid as recommended by your healthcare professional.
• Avoid alcohol during pregnancy.
• Attend your scheduled antenatal appointments so your health and your baby's development can be monitored.
• Seek medical advice if you develop new, persistent or worsening symptoms.

Pregnancy symptoms can change considerably as pregnancy progresses. Early symptoms may include tiredness, nausea, breast tenderness and frequent urination, while later pregnancy can bring physical changes such as back discomfort, heartburn, swelling, sleep difficulties and fetal movements.

Every pregnancy is different, and having few symptoms does not necessarily mean that anything is wrong. However, heavy bleeding, severe or persistent pain, severe headache with visual changes, sudden difficulty breathing, fever or a change in your baby's usual movements should be assessed promptly.