Pregnancy Symptoms by Week: What to Expect Each Trimester

Pregnancy symptoms vary significantly between people and even between pregnancies in the same person. What unites them is the cause: a cascade of hormonal changes — primarily rising hCG, oestrogen, and progesterone — that affect almost every system in the body. This guide covers what to expect trimester by trimester, and which symptoms always warrant a call to your midwife or GP.

Fact-Checked & Transparent: This article is fact-checked against current CDC, WHO, ACOG, and NHS guidelines. All health information is based on authoritative medical sources. Last verified: June 2026.

⚠️ MEDICAL DISCLAIMER

This article is educational information only. It is NOT a substitute for professional medical advice, diagnosis, or treatment.

Always consult your pediatrician or healthcare provider before making any medical decisions for your baby or child. Every baby is unique, and professional medical guidance is essential.

In case of emergency, call 911 or your local emergency number.

First Trimester: Weeks 1–12

The first trimester is when most symptoms are at their most intense, even though nothing is visible from the outside.

Nausea and Vomiting

Up to 80% of pregnant people experience nausea in the first trimester, and for around half, it includes vomiting. The NHS classifies it as "pregnancy sickness" rather than morning sickness because it can occur at any time of day.

The cause is the rapid rise in hCG (human chorionic gonadotropin), which peaks around weeks 8–10. For most people, nausea eases significantly between weeks 12–14 as hCG levels plateau.

Managing it: eat small amounts every 1.5–2 hours, keep plain crackers by your bedside to eat before getting up, and try ginger — ginger tea and ginger biscuits both have NHS endorsement for modest relief. Vitamin B6 (10–25 mg three times daily) has clinical evidence supporting its use. Acupressure wristbands (Sea-Bands) are safe and some people find them helpful.

When to contact your midwife: if you cannot keep fluids down for 24 hours, are losing weight, or feel dizzy on standing. These are signs of hyperemesis gravidarum, a severe form affecting 1–3% of pregnancies and requiring medical treatment and sometimes IV fluids.

Extreme Fatigue

Progesterone is a sedative-like hormone, and in the first trimester it rises sharply. Combined with the increased blood volume your body is building and the enormous energy demands of early placental development, the result is a level of fatigue that surprises most people. This is not tiredness that improves with a good night's sleep — it is a physiological heaviness.

It typically eases in the second trimester as the body adjusts, then returns in the third trimester as the uterus grows large and sleep becomes more difficult.

If fatigue is extreme throughout, particularly if it is accompanied by breathlessness or pallor, your midwife may check for iron deficiency anaemia, which affects around 25% of pregnancies and is easily treated.

Breast Changes

Breast tenderness and swelling begin as early as weeks 4–6, driven by oestrogen and progesterone preparing the breast tissue for milk production. The areolae may darken and small glands (Montgomery's tubercles) become visible on the areola — these secrete a lubricating substance that protects the nipple. A supportive, well-fitting bra without underwire often helps with the tenderness.

Frequent Urination

Your kidneys are working harder to filter an increased blood volume, and hCG stimulates kidney function directly. The uterus also begins pressing on the bladder from around week 8. Expect to urinate more frequently throughout pregnancy — this is normal and not a sign of infection unless accompanied by burning, pain, or unusual colour or odour.

Other Common First Trimester Symptoms

• Food aversions and cravings: strong aversions — particularly to meat, eggs, and coffee — are driven by heightened smell sensitivity caused by oestrogen. These usually fade in the second trimester.
• Constipation: progesterone slows intestinal motility; increase fibre and fluid intake and discuss with your midwife if severe.
• Light spotting at weeks 4–6: implantation bleeding is common and usually lighter than a period; the cervix is also more sensitive in pregnancy and may spot after sex or examination.
• Bloating and gas: progesterone relaxes smooth muscle throughout the body, including the gastrointestinal tract, slowing digestion and causing gas.
• Headaches: common in early pregnancy, partly due to increased blood volume. Paracetamol is safe; aspirin and ibuprofen should not be taken in pregnancy.

First Trimester Warning Signs

Contact your midwife or go to A&E for:

• Heavy bleeding (soaking a pad or passing clots) — can indicate miscarriage or ectopic pregnancy
• Severe one-sided abdominal pain, especially with shoulder tip pain — ectopic pregnancy is a medical emergency
• Fever above 38°C — infections require treatment; many antibiotics are safe in pregnancy
• Complete inability to keep any food or fluid down

Second Trimester: Weeks 13–27

For most people, the second trimester is the most comfortable. Nausea typically fades, energy returns, and the bump becomes visible.

Round Ligament Pain

Sharp, short pains on one or both sides of the lower abdomen — especially when standing up quickly, rolling over in bed, or coughing — are caused by the ligaments supporting the uterus stretching rapidly. The pain is brief (seconds to a minute) and does not indicate a problem. Slowing movements, supporting the bump when changing position, and a supportive pregnancy band can help.

Heartburn and Indigestion

The growing uterus presses upward against the stomach, and progesterone relaxes the valve between the oesophagus and stomach. Both effects allow stomach acid to reflux. This typically worsens from around week 20 onwards and can be one of the most persistent symptoms of late pregnancy.

Managing it: eat smaller meals, avoid lying down for 30–60 minutes after eating, prop the head of your bed up slightly, and avoid fatty and spicy foods. Antacids such as Gaviscon are safe in pregnancy; check with your GP before taking omeprazole or ranitidine.

Visible Veins and Varicose Veins

Increased blood volume (up 40–50% by the end of pregnancy) makes veins more prominent. Varicose veins can appear in the legs, vulva, or rectum (haemorrhoids). Compression socks worn from morning, regular walking, and elevating your legs when resting all help manage discomfort. Haemorrhoids can be treated with topical creams that are safe in pregnancy.

Skin Changes

The NHS notes that skin changes are extremely common in pregnancy. Linea nigra (a dark vertical line on the abdomen) appears in most pregnancies due to increased melanin production. Chloasma (darkening of patches on the face) affects up to 70% of pregnant people. Both are harmless and usually fade after birth.

Stretch marks on the abdomen, breasts, and thighs are caused by rapid skin stretching and are influenced significantly by genetics. Keeping skin moisturised reduces itching but there is limited evidence that creams prevent stretch marks from forming.

Fetal Movement

Most people feel the first fetal movements ("quickening") between weeks 16–22, though earlier in subsequent pregnancies. Initial sensations are often described as flutters, bubbles, or taps. By weeks 24–26, movements become more consistent and identifiable as kicks.

From around 24–28 weeks, the NHS advises that you should be aware of your baby's normal movement pattern. Any reduction in movement from your own normal should prompt a call to the maternity unit — do not wait until the next day. Reduced movement is not always a sign of a problem, but it does require assessment.

Second Trimester Warning Signs

• Persistent vomiting that was improving and has returned — may indicate a new problem
• Sudden swelling of face or hands, alongside headache or visual disturbances — possible pre-eclampsia; requires same-day assessment
• Any bleeding
• Fever or burning pain on urination — urinary tract infections are common in pregnancy and need prompt antibiotic treatment
• Severe abdominal pain

Third Trimester: Weeks 28–Birth

The third trimester brings increasing physical discomfort as the baby grows and internal space becomes limited.

Back Pain

The baby's weight shifts your centre of gravity and increases the curve of the lower spine. Combined with the hormone relaxin loosening ligaments to prepare the pelvis for birth, this commonly causes lower back pain. Gentle pelvic tilts, swimming, and pregnancy yoga can all help. The NHS recommends avoiding prolonged standing, wearing flat supportive shoes, and asking for a workplace risk assessment if your job requires heavy lifting or prolonged standing.

Pelvic girdle pain (PGP), previously called SPD, affects around 1 in 5 pregnant people and involves pain in the pelvis and hips. A physiotherapy referral from your midwife can significantly improve symptoms.

Braxton Hicks Contractions

These are practice contractions that prepare the uterus for labour. They feel like a tightening or hardening of the uterus, typically lasting 30–60 seconds. Unlike labour contractions, they are irregular, do not increase in frequency or intensity, and usually ease if you change position or drink water.

They typically become more noticeable in the third trimester and may increase in frequency in the weeks approaching your due date.

Swelling (Oedema)

Swelling of the feet, ankles, and lower legs is common in the third trimester, especially in warm weather and toward the end of the day. It is caused by fluid retention and pressure from the uterus on the veins returning blood from the legs. Elevating your feet, avoiding prolonged standing, and wearing compression socks help.

Sudden severe swelling of the face or hands, or a rapid increase in ankle swelling combined with headache, visual disturbance, or upper abdominal pain requires urgent assessment as it may indicate pre-eclampsia.

Sleep Difficulty

By the third trimester, a combination of physical discomfort, needing to urinate, restless legs, and the baby's movements make sustained sleep difficult. A full-length pregnancy pillow supporting the bump and between the knees significantly improves comfort.

The NHS advises sleeping on your side (left is preferred from 28 weeks) rather than on your back, which can compress the inferior vena cava — the large vein returning blood from the lower body to the heart. Going to sleep on your side is the key recommendation; if you wake on your back, simply roll back to your side.

Shortness of Breath

As the uterus expands into the chest cavity, it reduces lung capacity. Mild breathlessness on exertion is normal in late pregnancy. The baby usually "drops" (engages into the pelvis) in the final weeks of pregnancy, which may give some relief. Sudden or severe breathlessness, or breathlessness at rest, requires urgent medical assessment.

Third Trimester Warning Signs

• Regular, painful contractions before 37 weeks — may indicate preterm labour; call your maternity unit immediately
• Any vaginal bleeding
• Sudden reduction or absence of fetal movement — contact your maternity unit the same day for monitoring
• Visual disturbances, severe headache, or right-sided upper abdominal pain — signs of pre-eclampsia requiring emergency assessment
• Signs of water breaking (PROM) — a gush or slow trickle of fluid from the vagina; call your maternity unit

Frequently Asked Questions

When do pregnancy symptoms usually start?

The most common early symptoms — breast tenderness, fatigue, and mild nausea — typically begin around weeks 5–6, shortly after a missed period. Some people notice changes from 3–4 weeks. Others have few noticeable symptoms until week 8 or later. Both are normal.

Is it normal to have no pregnancy symptoms?

Some people have very mild or almost unnoticeable symptoms, particularly in the first trimester. The absence of symptoms does not indicate a problem. Conversely, severe symptoms like hyperemesis do not indicate a healthier pregnancy — symptom severity is not a reliable guide to how the pregnancy is progressing.

When does nausea usually stop in pregnancy?

For most people, first trimester nausea peaks around weeks 8–10 and eases significantly by weeks 12–14. Around 10–20% of people have some nausea beyond 14 weeks. Hyperemesis gravidarum (severe nausea and vomiting) can persist for much longer and requires medical management.

What symptoms are always worth calling your midwife about?

Any vaginal bleeding; fever above 38°C; severe headache with visual disturbance; sudden severe swelling of the face or hands; reduction in fetal movement; signs of water breaking before 37 weeks; any symptom that is worrying you — your midwife would always rather you call than wait.

Is itching in pregnancy normal?

Mild itching of the skin, particularly over the stretching abdomen, is normal. Intense itching of the hands and feet — particularly at night — may indicate obstetric cholestasis (intrahepatic cholestasis of pregnancy), a liver condition that requires urgent assessment. Contact your midwife or GP if you develop this type of itching.

Can I take paracetamol for pain in pregnancy?

Paracetamol is the pain reliever considered safest in pregnancy and is recommended by the NHS and NICE for pain management when needed. Ibuprofen and aspirin should be avoided, especially after 30 weeks. Always use the lowest effective dose for the shortest time.

Key Takeaways

• First trimester symptoms (nausea, fatigue, breast changes, frequent urination) are driven by rapidly rising hCG, oestrogen, and progesterone.
• Most people find the second trimester more comfortable as hCG stabilises and the body adjusts to hormonal changes.
• From 24–28 weeks, track your baby's movement pattern and report any reduction promptly — do not wait until the next appointment.
• Certain symptoms at any stage need same-day assessment: heavy bleeding, severe headache with visual disturbance, sudden face or hand swelling, and reduced fetal movement.
• Symptom severity does not reliably indicate pregnancy health — some very healthy pregnancies involve minimal symptoms.
• Always contact your midwife, GP, or maternity unit if you are worried about a symptom, regardless of the stage of pregnancy.

📋 SOURCES & FACT-CHECKING

This article is compiled and verified against these authoritative sources: - CDC (Centers for Disease Control & Prevention) - WHO (World Health Organization) - ACOG (American College of Obstetricians and Gynecologists) - NHS (National Health Service) - AAP (American Academy of Pediatrics)

Last verified: June 2026

Educational content only. Always consult your pediatrician for medical decisions.

Related Articles

• First Trimester Guide
• Second Trimester Guide
• Third Trimester Guide
• Prenatal Vitamins Guide
• When To Go To Hospital Labor