Week 1
Trimester 1Days 0+0 to 0+6
Week 1 of pregnancy is a little unusual — you are not actually pregnant yet. Pregnancy is traditionally dated from the first day of your last menstrual period (LMP), even though conception has not occurred. Doctors use this system because the exact date of ovulation and fertilisation is often unknown. During Week 1, your body is beginning a new menstrual cycle and preparing for a possible pregnancy later in the month.
Development highlights
- check_circleYour menstrual period begins.
- check_circleHormone levels change to start a new cycle.
- check_circleSeveral follicles begin developing in the ovaries.
- check_circleOne follicle will eventually become dominant and release an egg during ovulation.
Fun fact
If you become pregnant this cycle, your pregnancy countdown will still begin from this week — even though conception has not happened yet.
Weekly checklist
- Take prenatal vitamins if trying to conceive.
- Stay hydrated.
- Eat a balanced diet.
- Get regular exercise.
- Track your menstrual cycle.
- Learn about ovulation and fertile windows.
Frequently asked questions
Why am I considered pregnant if there is no baby yet?
Pregnancy is traditionally dated from the first day of your last menstrual period. This provides a consistent way for healthcare providers to calculate due dates.
Can I get pregnant during Week 1?
Conception usually occurs later in the cycle, after ovulation. Week 1 is the menstrual period phase, not the fertile window.
Should I start prenatal vitamins now?
Yes. Many healthcare providers recommend starting prenatal vitamins before conception occurs, as folic acid is most important in the very early weeks of pregnancy.
Is bleeding normal during Week 1?
Yes. For most people, Week 1 corresponds with their menstrual period.
Related tools
shopping_bagHelpful picks for Trimester 1
Browse all pregnancy products →Frida Mom Anti-Nausea Acupressure Bands
Drug-free acupressure wristbands for morning sickness relief — wear during the first trimester to ease nausea without medication.
Lokaheadr 1st Pregnancy Essentials Kit
Curated first-pregnancy essentials gift set for new moms-to-be — everything you need for a comfortable first trimester.
Momcozy Maternity Pregnancy Pillow
Full-length maternity pillow with removable sections for bump support, back relief, and comfortable side sleeping.
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Medical information disclaimer
The content on this page is provided for general informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.
Always consult your GP, midwife, health visitor, paediatrician, or other qualified healthcare provider before making decisions about your health or your child's health and development. Never ignore or delay seeking professional advice because of something you have read on BabyScout. If you think there is a medical emergency, call 999 (UK) or your local emergency services immediately.