Pregnancy Week by Week: Find Your Week
This is the DueDateLab pregnancy week-by-week guide. Detailed pages are currently available for weeks 4 to 9, with weeks 10 to 42 planned for later additions. Weeks 1 to 3 appear as context rows because pregnancy dating starts from the first day of the last menstrual period, before most people have a positive test. The goal is a clear, source-backed weekly map that connects dates, symptoms, development, and safe next steps without turning a week number into a personal medical conclusion.
How pregnancy weeks are counted
Pregnancy weeks are counted from the first day of the last menstrual period, often shortened to LMP. NHS due-date guidance asks for that date, and Mayo Clinic describes pregnancy's full counted span as 40 weeks from the start of the last period.[1][2] That is why the counted week can run ahead of time since fertilisation. It is also why a week-by-week guide needs a short dating explanation before jumping into development details.
Weeks 1 to 3
Pregnancy weeks are counted from the first day of the last menstrual period, which is why a week-by-week pregnancy chart starts before most people have a positive test. Weeks 1 to 3 are included here as context rows only, not as separate pages. The individual guides begin at week 4, when NHS week-by-week guidance starts to discuss missed-period timing, early symptoms, implantation-related spotting, and the first practical testing questions.
Detailed week pages, weeks 4 to 9
The table below links the detailed weekly pages currently available. Each row is short by design. The detailed leaf for that week carries the fuller source map, safety callout, and calculator links.
| Week | What may be happening | Guide |
|---|---|---|
| Weeks 1 to 3 | Context only: pregnancy is counted from LMP before most people have a positive test. | See the explainer above |
| Week 4 | Missed-period timing, implantation-related spotting, early symptoms, and first testing questions may overlap.[3] | 4 weeks pregnant |
| Week 5 | Many people realise they are pregnant around this point; early brain, spinal-cord, and heart formation are underway.[4] | 5 weeks pregnant |
| Week 6 | Rapid early development continues, and symptoms such as nausea or tiredness may become more noticeable.[5] | 6 weeks pregnant |
| Week 7 | Brain, face, and limb structures continue developing, while tiredness, sickness, mood changes, or thirst may show up.[6] | 7 weeks pregnant |
| Week 8 | The placenta is getting ready to support nutrient and oxygen exchange, and common early symptoms may continue.[7] | 8 weeks pregnant |
| Week 9 | Hormone levels and symptoms can feel prominent, while internal organs, bones, face, hands, and feet keep developing.[8] | 9 weeks pregnant |
| Weeks 10 to 42 | More weekly guides will be added later. | Coming later |
Safety in early pregnancy
Safety in early pregnancy
Each detailed week page includes a full early-pregnancy safety section anchored to NHS guidance.[9] If you are pregnant and have light bleeding or spotting, contact your maternity unit, an early pregnancy unit if you are under 20 weeks, or NHS 111 if you cannot reach those services. Call emergency services for bleeding with severe tummy pain, shoulder pain, faintness, dizziness, loss of consciousness, or heavy bleeding that soaks a pad soon after putting it on.
Use our Due Date Calculator
Use the Due Date Calculator if you want to estimate your due date from LMP using the 40-week pregnancy convention.[2] The calculator gives a dated result first, then you can use this hub to open the matching weekly guide. If your question is how a week number converts into months, use the Pregnancy Weeks to Months Calculator and Chart.
The hub is a navigation layer; each weekly guide explains source-backed development, common symptoms, safety routing, and relevant calculator context. If you only know a due date, start with the calculator. If you know your LMP date or current week count, start with the matching row above.
The weekly series is being expanded gradually so each page can be sourced and reviewed properly. The early post-test window from week 4 through week 9 is available now, and more weekly guides will be added later.
Related
Sources
- Pregnancy due date calculator — NHS. LMP dating and pregnancy-length guidance. Last verified 2026-04-30.
- Fetal development: The first trimester — Mayo Clinic. Forty-week pregnancy convention and early development. Last verified 2026-04-30.
- Week 4 — NHS Best Start in Life. LMP convention and early week-4 symptoms. Last verified 2026-04-30.
- Week 5 — NHS Best Start in Life. Pregnancy awareness and early development. Last verified 2026-04-30.
- Week 6 — NHS Best Start in Life. Week-6 development and symptoms. Last verified 2026-04-30.
- Week 7 — NHS Best Start in Life. Week-7 development and symptoms. Last verified 2026-04-30.
- Week 8 — NHS Best Start in Life. Placenta and week-8 development. Last verified 2026-04-30.
- Week 9 — NHS Best Start in Life. Week-9 symptoms and development. Last verified 2026-04-30.
- Vaginal bleeding in pregnancy — NHS. Early-pregnancy safety routing. Last verified 2026-04-30.