Pregnancy Symptoms by Week: What's Normal, What's Not

Every pregnancy is different, but most symptoms follow a recognizable arc driven by predictable hormonal changes. Knowing what to expect — and when to expect it — helps you tell the difference between normal pregnancy physiology and something worth calling your provider about. This guide walks week by week from the first positive test (around week 4) through delivery (week 40), grounded in ACOG guidance on normal pregnancy.

Use the Pregnancy Week Calculator to identify exactly where you are in your pregnancy as you read.

Weeks 4–5: the first signs

Most pregnancy tests become reliably positive in week 4 (the week after a missed period in a 28-day cycle). At this point, hCG — human chorionic gonadotropin — is rising rapidly, roughly doubling every 48–72 hours in early pregnancy.

Symptoms common in weeks 4–5:

• Breast tenderness and fullness. Often the earliest and most consistent symptom. Progesterone and hCG increase blood flow and hormone stimulation to breast tissue.
• Mild fatigue. Progesterone has a sedative effect; early blood volume expansion also contributes.
• Light spotting (implantation bleeding). Some women notice light pink or brown spotting around weeks 4–5 as the embryo implants. This lasts 1–3 days and is lighter than a period.
• Mild pelvic cramping. The uterus begins growing; some cramping is normal.
• Frequent urination. Begins early due to hCG effects on kidneys and increasing blood volume.

Concerning at this stage: Bleeding heavier than light spotting, severe one-sided pain (possible ectopic pregnancy — peak risk is before 8 weeks).

Weeks 6–9: peak first-trimester symptoms

This is when most women feel pregnancy most intensely. hCG levels peak around weeks 8–10, and most symptoms track that curve.

Nausea and vomiting (morning sickness)

Affects 70–80% of pregnant women (ACOG). The name “morning sickness” is misleading — nausea can occur at any time of day or night. It is thought to be primarily driven by hCG and, for some women, a heightened sensitivity to estrogen.

Nausea typically begins around week 5–6, peaks at weeks 8–10, and resolves for most women by weeks 12–14. For approximately 1–2% of women, nausea and vomiting is severe and persistent — a condition called hyperemesis gravidarum (HG) — requiring medical management to prevent dehydration, nutritional deficiency, and electrolyte imbalance.

ACOG-recommended management for moderate nausea includes vitamin B6 (pyridoxine) 10–25 mg three times daily as first-line, with doxylamine added if B6 alone is insufficient (ACOG Practice Bulletin 189, 2018).

Helpful strategies (evidence-based):

• Small, frequent meals — an empty stomach worsens nausea
• Cold foods often tolerated better than hot foods
• Avoiding triggers (commonly: cooking smells, strong perfume, fatty or spicy foods)
• Ginger (tea, supplements) has moderate evidence for nausea reduction
• Sea-bands (acupressure wrist bands) — evidence is modest but they are harmless

Other common symptoms, weeks 6–9:

• Heightened sense of smell. Driven by estrogen; one of the most reported early pregnancy features. Food and environmental odors that were previously neutral become overwhelming.
• Food aversions. Often linked to heightened smell. Many women find aversions to meat, coffee, and eggs.
• Food cravings. Less well understood physiologically; variable between individuals.
• Extreme fatigue. Often its worst in weeks 6–10. The body is building a placenta; cardiac output is rising; hormone levels are at their highest. Rest is appropriate.
• Constipation. Progesterone relaxes smooth muscle throughout the body, slowing gastrointestinal motility. Iron supplementation (standard in prenatal vitamins) worsens this. Adequate fluid, fiber, and gentle activity help.
• Bloating. Related to slower GI motility.
• Heartburn. Progesterone relaxes the lower esophageal sphincter; stomach acid can reflux upward. Worsens through pregnancy.
• Saliva production (ptyalism). Some women produce markedly more saliva in early pregnancy, a phenomenon poorly understood but recognized clinically.
• Mood changes. Progesterone and hCG affect neurotransmitter signaling. Emotional lability, tearfulness, irritability, and anxiety are common.
• Headaches. Increased blood volume and hormonal shifts can trigger headaches. Dehydration and caffeine withdrawal (many women cut coffee at pregnancy confirmation) are also contributors.
• Lightheadedness. Blood volume is expanding faster than the cardiovascular system can fully adapt initially. Standing up quickly can produce dizziness.

Weeks 10–13: late first trimester

For most women, nausea begins to ease as hCG plateaus (around week 10) and then starts to decline slightly. The placenta is beginning to take over progesterone production from the corpus luteum.

New or continuing symptoms:

• Round ligament pain. The round ligaments — which support the uterus — stretch as the uterus grows. Sharp, brief stabbing pain on one or both sides of the lower abdomen or groin, triggered by position change, coughing, or sudden movement. Harmless but startling. A heating pad and changing positions slowly can help.
• Visible veins. Blood volume increases approximately 40–50% across pregnancy (ACOG). Veins in the breasts and abdomen may become more visible.
• Increased vaginal discharge (leukorrhea). Normal, white or clear discharge increases under estrogen stimulation. Contact your provider if it has an unusual odor, is green or yellow, or is accompanied by itching (possible infection).

Symptoms typically improving:

• Nausea (for most — not all — women)
• Extreme fatigue (often lightens in the second trimester)
• Breast tenderness (often stabilizes)

Weeks 14–27: the second trimester

The second trimester is the stretch from week 14 through week 27. For most women, it is the most comfortable period. Miscarriage risk has dropped sharply. Energy often improves. Nausea is usually gone.

Symptoms common in the second trimester:

• Fetal movement (quickening). Felt first as fluttery sensations, often described as bubbles or light taps. First-time mothers typically feel movement between weeks 18–22; those who have been pregnant before often feel it slightly earlier (weeks 16–18).
• Back pain. As the uterus grows forward, the center of gravity shifts. Lumbar strain is nearly universal from around week 16 onward. Supportive footwear, avoiding prolonged standing, and prenatal yoga or swimming can help.
• Linea nigra. A darkening vertical line from the navel to the pubic bone, caused by increased melanin production. Normal; fades after delivery.
• Skin changes. Chloasma (melasma, “mask of pregnancy”) — darkening patches on the face from elevated estrogen and progesterone stimulating melanocytes. Worsened by sun exposure; sunscreen is the primary mitigation.
• Nasal congestion (pregnancy rhinitis). Increased estrogen causes mucosal engorgement in the nasal passages. Saline rinse; avoid medicated nasal sprays unless cleared by your provider.
• Leg cramps. Common from around week 16 onward, often worse at night. Cause is not fully established; hydration, stretching before bed, and magnesium supplementation (discuss with your provider) may help.
• Heartburn and acid reflux. Worsens through the second and third trimesters as the uterus pushes the stomach upward. Small meals, avoiding lying down after eating, and avoiding acidic or fatty foods help.
• Swelling (edema). Mild ankle and foot swelling is common as blood volume and fluid retention increase, especially in the afternoon and after standing. Elevating feet, compression socks, and avoiding prolonged standing help. Sudden or severe swelling — especially in the face or hands — combined with headache or visual changes can indicate preeclampsia and requires immediate contact with your provider.
• Hemorrhoids. Increased blood volume, growing uterus pressure on pelvic veins, and constipation all contribute. Stool softeners (safe in pregnancy, ask your provider), Sitz baths, and topical witch hazel can help.
• Breast changes. The areolas continue darkening; colostrum (early breast milk) may begin to leak from around week 16 in some women, though it more commonly begins in the third trimester.

Second-trimester screening:

• Anatomy scan: detailed fetal ultrasound at weeks 18–22, assessing fetal anatomy, placental position, amniotic fluid, and cervical length in some practices.
• Glucose challenge test: typically weeks 24–28 to screen for gestational diabetes.
• Rh-negative patients receive Rh immunoglobulin (RhoGAM) at 28 weeks.

Weeks 28–40: the third trimester

The third trimester runs from week 28 through delivery. The fetus doubles in weight in this period, from roughly 900 grams to over 3,000 grams. The physical demands on the pregnant body are at their highest.

Common third-trimester symptoms:

• Shortness of breath. The expanding uterus pushes the diaphragm upward by up to 4 cm, reducing lung expansion capacity. The baby dropping (lightening) into the pelvis in the last few weeks often provides relief.
• Frequent urination (again). The growing fetus puts direct pressure on the bladder. Urinary leakage (stress incontinence) with coughing or sneezing is common; pelvic floor exercises (Kegel exercises) can help.
• Braxton Hicks contractions. Irregular, painless tightening of the uterus, typically sporadic and not progressively strengthening. They are practice contractions — the uterus preparing for labor. Dehydration and physical activity tend to increase them. If contractions become regular (especially every 5–10 minutes), progressively stronger, or are accompanied by pelvic pressure or back pain before 37 weeks, contact your provider (possible preterm labor).
• Pelvic girdle pain and pubic symphysis discomfort. Relaxin — a hormone produced throughout pregnancy — loosens ligaments, which can cause the pubic symphysis and sacroiliac joints to become painful. Waddling gait, pain with stairs or rolling over in bed are classic presentations. A pelvic floor physiotherapist can provide targeted management.
• Insomnia. Difficulty finding a comfortable sleep position, frequent urination at night, leg cramps, and anxiety all contribute. Left-side sleeping is recommended in the third trimester — it optimizes venous return to the heart and uterine blood flow.
• Itching. Mild itching of the abdomen as skin stretches is normal. Generalized severe itching — especially on the palms and soles, worse at night — can indicate intrahepatic cholestasis of pregnancy (ICP), a liver condition requiring medical evaluation and monitoring (ACOG Practice Bulletin 232, 2021).
• Lightning crotch. Sharp, brief shooting pain in the vagina, rectum, or inner thighs, caused by the baby’s head pressing on cervical nerves or pelvic floor nerves. Normal in late pregnancy.
• Colostrum leaking. Yellow to clear early milk from weeks 28 onward in many women.
• Increased Braxton Hicks frequency and intensity.

Fetal movement monitoring: After 28 weeks, ACOG recommends awareness of fetal movement patterns. While specific “kick count” protocols vary, the principle is: you should be feeling your baby move every day. A perceived decrease or change in your baby’s movement pattern warrants a call to your provider for fetal monitoring. Do not wait until the next scheduled appointment if you notice reduced movement.

Symptoms that are never normal: a quick reference

The bottom line

Most pregnancy symptoms are driven by hormones doing exactly what they are supposed to do: hCG and progesterone causing nausea and fatigue in the first trimester, estrogen and relaxin causing ligament softening and fluid changes through the second, and the sheer mechanical weight of a full-term fetus causing discomfort in the third. Knowing the expected arc makes it easier to distinguish normal physiology from warning signs.

Track your pregnancy week by week in the Pregnancy Week Calculator so you have context for what to expect at each stage. When a symptom concerns you, call your provider — no prenatal care provider will fault you for calling about something that turns out to be normal. The symptoms in the “never normal” table above are always worth a same-day call or emergency evaluation.