When Do Pregnancy Symptoms Start? A Week-by-Week Timeline
Reviewed by Safi Allah Khan
Medically reviewed by: Safi Allah Khan · Written by the Momi team · Last updated 20 October 2026
Quick answer: When do pregnancy symptoms start? For most people, at around 4 to 6 weeks of pregnancy, counted from the first day of your last period. That's around when your period is due, about two weeks after conception. A missed period is usually the first sign, followed by tiredness, sore breasts and nausea. Some people notice nothing until later.
This page is about timing. For a full list of early signs, see early pregnancy symptoms, and for the whole nine months, pregnancy symptoms week by week.
Why "week 4" is only two weeks after conception
Pregnancy is counted from the first day of your last period, not from conception. So in a 28-day cycle:
- Weeks 1 to 2: your period and the run-up to ovulation. You're not pregnant yet.
- Week 3: ovulation and fertilisation, then the fertilised egg travels to the uterus.
- Week 4: implantation; your period is due at the end of this week.
That's why the due date calculator adds two weeks before conception. See why does a pregnancy calculator add 2 weeks?.
Pregnancy symptoms timeline
| Pregnancy week (from last period) | Days after conception (approx.) | What you might notice |
|---|---|---|
| 3 | 0–7 | Usually nothing |
| 4 | 7–14 | Light spotting (implantation bleeding), mild cramps, missed period at the end |
| 5 | 14–21 | Tiredness, sore breasts, needing to pee more |
| 6 | 21–28 | Nausea (with or without vomiting), sensitivity to smells, mood changes |
| 7–8 | 28–42 | Nausea often building, food aversions, bloating, constipation |
| 9–12 | 42–70 | Symptoms often at their strongest, then easing for many by 12 to 14 weeks |
The NHS says early signs usually start at 4 to 6 weeks. ACOG says nausea and vomiting usually start before 9 weeks. Everyone is different: you may have all of these, some, or none.
The earliest symptoms (weeks 4 to 6)
According to the NHS, signs you may notice first include:
- a missed period
- a bleed like a very light period, or spotting, around when your period is due (implantation bleeding)
- feeling or being sick, at any time of day
- feeling extremely tired after your usual activities
- sore, larger or tender breasts
- needing to pee more often
- constipation
- more vaginal discharge (without soreness or itching)
- a metallic taste, sensitivity to smells, cravings or aversions
- mood changes
Implantation
After fertilisation, the egg takes several days to reach the uterus and implant. The NHS says the pregnancy hormone hCG starts to be produced around 6 days after fertilisation, and rising hCG is what pregnancy tests detect and what drives many early symptoms.
Mayo Clinic says implantation bleeding can occur about 10 to 14 days after conception. It's typically light spotting rather than a flow, and many people don't have it at all.
Symptoms vs PMS
Many early pregnancy symptoms overlap with premenstrual syndrome. The NHS lists common PMS symptoms as mood swings, tiredness, bloating or cramping, breast tenderness, headaches, spots and food cravings.
| Clue | More likely PMS | More likely pregnancy |
|---|---|---|
| Your period | Arrives as usual | Doesn't arrive |
| Bleeding | A normal period | Light spotting only, or none |
| Nausea | Uncommon | Common, often from about 6 weeks |
| Breast soreness | Eases when your period starts | Continues and may increase |
| Timing | Eases once your period starts | Builds over the following weeks |
The only way to know is a test. Read more in pregnancy vs period symptoms.
When to test
The NHS says:
- tests are most reliable from the first day of a missed period
- if you don't know when your period is due, test at least 21 days after unprotected sex
- you can test at any time of day
- a positive result is almost certainly correct; a negative result is less reliable if you test too early
If your test is negative but your period still doesn't come, test again a few days later.
Why symptoms vary so much
Some people feel sick within days of a missed period; others feel almost nothing for weeks. Differences in hormone levels, sensitivity to those hormones, and whether you've been pregnant before all play a part. Symptoms can also come and go from day to day. A few things that can make early symptoms easier to miss or mistake:
- Irregular cycles: if your periods aren't regular, it's harder to know when one is "late". Count from the first day of your last period, or test 21 days after unprotected sex.
- Contraception: the NHS says hormonal contraception won't stop a pregnancy test working, so test if you're unsure.
- Stress or illness: both can delay a period or cause tiredness and nausea, so a test is the only way to be sure.
When to get help
Contact a doctor urgently if you have a positive test and severe pain on one side of your lower tummy, shoulder tip pain, heavy bleeding or you feel faint. ACOG says these can be signs of an ectopic pregnancy, which needs emergency care. If you have any bleeding or pain in early pregnancy, contact your midwife, doctor or early pregnancy unit.
How Momi helps
Once you've got a positive test, set your due date in Momi from your last period or conception date. You'll see your current week, trimester and baby size, with daily and weekly tips. Add your first appointment with medicine reminders, and start your diary while it's all new.
Download Momi free on the App Store or Google Play. Free with ads; optional Premium.
Related: first trimester symptoms · 4 weeks pregnant · How Many Weeks Pregnant Am I?
Sources
- NHS, Signs and symptoms that might mean you're pregnant
- NHS, Doing a pregnancy test
- Mayo Clinic, Symptoms of pregnancy: What happens first
- ACOG, Morning Sickness: Nausea and Vomiting of Pregnancy
- NHS, PMS (premenstrual syndrome)
- ACOG, Ectopic Pregnancy
Medical disclaimer: Momi and this website provide general information, not medical advice. Always talk to your doctor or midwife; in an emergency call your local emergency number.
FAQ
How soon do pregnancy symptoms start?
The NHS says early signs usually start at around 4 to 6 weeks of pregnancy, counted from the first day of your last period. That's around the time your period is due, about 2 weeks after conception. Some people notice nothing until later.
Can you have pregnancy symptoms 1 week after conception?
It's unlikely. The fertilised egg takes several days to implant, and the NHS says the pregnancy hormone hCG only starts being produced around 6 days after fertilisation. Symptoms in the first week are more likely to be part of your normal cycle.
When does implantation bleeding happen?
Mayo Clinic says implantation bleeding can happen about 10 to 14 days after conception, around when your period is due. It's usually light spotting, much less than a period. Not everyone has it.
When should I take a pregnancy test?
The NHS says tests are most reliable from the first day of a missed period. If you don't know when your period is due, test at least 21 days after unprotected sex. A positive result is almost certainly right; a negative one is less reliable if you test early.
Is it normal to have no symptoms at 6 weeks?
Yes. Not everyone has symptoms, and some people feel very little until later in the first trimester. Having no symptoms doesn't mean something is wrong. If you have bleeding or pain, contact your midwife or doctor.
Related guides
Track this in Momi
Momi is a free pregnancy tracker app for iPhone and Android that follows pregnancy week by week, estimates the due date, and keeps a pregnancy journal, weight log, kick counter and contraction timer in one place.
