Pregnancy Symptoms by Week: What to Expect Each Trimester

Every pregnancy is different, but there are common patterns in how your body responds to pregnancy hormones. Understanding these symptoms by week can help you distinguish between normal changes and warning signs that need medical attention.

First Trimester: Weeks 1-12

The first trimester brings the most dramatic hormonal shifts. You may not even know you're pregnant during weeks 1-4, as symptoms often begin around the time of your missed period.

Week 4-6: Early Hormonal Changes

• Missed period — Usually the first sign (week 4)
• Implantation bleeding — Light spotting when the embryo attaches to the uterus
• Breast tenderness — Breasts may feel sore, swollen, or tingly
• Frequent urination — Your body produces more blood, making your kidneys work harder
• Fatigue — Progesterone spikes make you sleepy

Week 7-9: Morning Sickness Peaks

• Nausea and vomiting — Can happen any time of day; peaks around week 9
• Food aversions — Suddenly repelled by smells or foods you used to love
• Heightened sense of smell — Perfumes, cooking odors, or coffee may trigger nausea
• Mood swings — Emotional highs and lows are normal
• Bloating — Hormonal changes slow digestion

Week 10-12: Energy Returns (Slightly)

• Reduced nausea — Most women feel improvement by week 12
• Visible baby bump — The uterus rises above the pelvis
• Headaches — Common due to hormonal shifts and blood volume changes
• Constipation — Iron in prenatal vitamins plus slower digestion
• Dizziness — Low blood sugar or standing up too fast

Second Trimester: Weeks 13-26

Many women call this the "honeymoon phase" of pregnancy. Nausea fades, energy returns, and you may start feeling the baby move. However, new symptoms emerge as your body grows.

Week 13-16: Energy & Movement

• Return of energy — Morning sickness usually eases dramatically
• First movements (quickening) — Often felt around week 16-20, described as "flutters"
• Nasal congestion — Increased blood flow to the mucus membranes
• Bleeding gums — Hormones make gums more sensitive
• Skin changes — Stretch marks may begin; linea nigra (dark line on belly) may appear

Week 17-20: Visible Changes & Tests

• Obvious baby bump — You'll probably need maternity clothes now
• Back pain — Center of gravity shifts as your belly grows
• Round ligament pain — Sharp, brief pains on the sides of your belly
• Leg cramps — Especially at night; stretching helps
• Anatomy scan ultrasound — Around week 20; a detailed look at baby's development

Week 21-26: Growing Pains

• Braxton Hicks contractions — Irregular "practice" contractions, especially later in trimester
• Stretch marks — Appear where skin stretches fastest (belly, hips, breasts, thighs)
• Swollen ankles and feet — Due to increased blood volume and pressure on veins
• Itchy skin — Belly and breasts may itch as they stretch
• Sciatica — Shooting pain down the leg from pressure on the sciatic nerve

Third Trimester: Weeks 27-40+

The final stretch brings physical discomfort as your baby gains weight and positions for birth. You may feel tired, uncomfortable, and eager for delivery—all completely normal.

Week 27-32: The Weight Gain Phase

• Shortness of breath — Uterus pushes up on your diaphragm
• Heartburn — Uterus presses on the stomach
• Frequent urination — Baby's weight presses on your bladder
• Pelvic pressure — Baby's head bears down on your pelvis
• Insomnia — Hard to get comfortable at night

Week 33-36: Preparing for Birth

• Braxton Hicks intensify — May feel like real contractions
• Nesting instinct — Sudden urge to clean and organize
• Colostrum production — Breasts may leak yellowish fluid
• Bloody show — Pink-tinged mucus as cervix begins to dilate
• Weight gain slowdown — Most rapid weight gain is done

Week 37-42: The Home Stretch

• Baby drops (lightening) — Baby descends into the pelvis; easier to breathe, more pelvic pressure
• Loss of mucus plug — Can happen days or weeks before labor
• Cervical changes — Cervix starts to soften, thin, and dilate
• Water breaking — Membrane ruptures; call your doctor immediately
• Regular contractions — When they're 5 minutes apart, lasting 1 minute, for 1 hour, it's time to go

When Symptoms Are Normal vs. Warning Signs

Most pregnancy symptoms are normal, but some require immediate medical attention. Contact your healthcare provider if you experience:

• Heavy vaginal bleeding — Soaking a pad in an hour
• Severe abdominal pain — Could indicate miscarriage or ectopic pregnancy
• Fever over 100.4°F (38°C) — Could be infection
• Severe headache with vision changes — Possible preeclampsia sign
• Decreased fetal movement — Especially in the third trimester
• Painful urination or back pain — Possible UTI or kidney infection
• Sudden severe swelling — Hands, face, or around eyes could be preeclampsia

When to Call Your Doctor

Pregnancy hormones can make everything feel strange. When in doubt, call your provider. It's always better to check. Keep their after-hours number saved in your phone.

Tracking Your Pregnancy

Use our free due date calculator to find out exactly which week you're in, then reference this guide to understand what changes to expect. Combine it with our first trimester checklist for a complete preparation plan.