Pregnancy symptoms week by week through the first trimester

Many people look up pregnancy symptoms week by week to understand what stage their body is at. First, how weeks are counted: pregnancy is dated from the first day of your last period, not from conception. With a 28-day cycle, conception usually happens towards the end of week 2. Everyone is different, so the timings below are typical ranges, not a fixed timetable.

Weeks 1 to 4: before and just after conception

• Weeks 1–2: you have your period and then ovulate. You are not actually pregnant yet, so there are no signs.
• Week 3: the fertilised egg travels to the womb. According to the NHS, hCG production starts around six days after fertilisation, but too little for a test to pick up.
• Week 4: around when your period is due. Some people notice light pink or brown spotting, mild cramps or tender breasts. This is when your period is missed and a home test starts to work.

Weeks 5 to 8: symptoms become clearer

• Nausea: the NHS says most people notice it around weeks 4 to 6, and it can happen at any time of day.
• Tiredness beyond the usual, wanting to sleep early.
• Needing to pee more, including at night.
• Breasts feeling heavy and sore, with darker nipples.
• A sharper sense of smell, changing tastes, a metallic taste.

This is the time to book your first appointment. WHO recommends the first antenatal contact within the first 12 weeks, and many hospitals offer a scan to confirm the pregnancy is in the womb and check the heartbeat.

Weeks 9 to 12: sickness may peak

• Nausea and tiredness may still be strong. The NHS says sickness usually eases and clears by around weeks 16 to 20, though it can last longer for some.
• Constipation, bloating and heartburn.
• Mood changes while hormone levels are high in the first 12 weeks.
• No obvious bump yet, but waistbands may feel tighter.

Hospitals in Vietnam usually schedule a nuchal translucency scan and screening tests around weeks 11 to 13. Your doctor will give you exact dates.

Pregnancy symptoms week by week at a glance

Red-flag symptoms that need a doctor now

In the first 12 weeks, Mayo Clinic advises contacting your doctor straight away for moderate to heavy vaginal bleeding, or bleeding with belly pain, cramping, fever or chills. The NHS also warns about:

• Pain low down on one side or shoulder tip pain: possibly an ectopic pregnancy, usually between weeks 4 and 12.
• Sudden severe pain, dizziness, fainting or looking very pale: an emergency.
• Being unable to keep food or fluids down for 24 hours, very dark urine or not peeing for more than eight hours: possible severe pregnancy sickness that needs treatment.

To see which week you are in today, use our due date calculator. For vitamins, iron and folic acid, browse prenatal vitamins for reference and always ask your doctor first. Still not sure you are pregnant? Read early signs of pregnancy.

Remember that symptoms are not a measure of how well a pregnancy is going. Some people feel very sick and others feel almost nothing, and both can be completely normal. Your check-ups, scans and blood tests are what tell your doctor how you and your baby are doing, so keep those appointments even on days you feel fine.

Based on NHS, WHO and Mayo Clinic guidance; every pregnancy is different, so follow the doctor caring for you.