Week 3
Trimester 1Days 2+0 to 2+6
Week 3 is a very exciting milestone because this is often the week when conception occurs. If sperm successfully fertilises the egg, your baby's unique genetic makeup is created at this moment. Eye colour, hair colour, biological sex, and thousands of other characteristics are determined from the very beginning. Most people still have no idea they are pregnant, but an incredible amount is already happening behind the scenes.
Development highlights
- check_circleOvulation occurs and the egg is released from the ovary.
- check_circleIf sperm reaches the egg, fertilisation forms a single cell called a zygote.
- check_circleThe zygote immediately begins dividing — one cell becomes two, two become four, and so on.
- check_circleThe dividing cells travel through the fallopian tube toward the uterus.
- check_circleAll of the baby's genetic information is already present from this moment.
Fun fact
Your baby's biological sex is determined at the moment of fertilisation. Whether your baby has XX or XY chromosomes is decided before you even know you are pregnant.
Weekly checklist
- Continue taking prenatal vitamins.
- Stay hydrated.
- Eat a balanced diet.
- Get enough sleep.
- Avoid smoking and excessive alcohol.
- Be patient during the waiting period.
Frequently asked questions
Is my baby already developing?
If fertilisation has occurred, yes. The fertilised egg is already dividing into more cells and beginning the earliest stages of development, even though it is far too small to see.
Can I take a pregnancy test this week?
Usually not. It is too early for most tests to detect pregnancy during Week 3, as the pregnancy hormone hCG has not yet built up to detectable levels.
Can I have symptoms already?
Most people do not experience noticeable pregnancy symptoms during Week 3. The fertilised egg has not yet implanted, so pregnancy hormones are still very low.
When will implantation happen?
Implantation usually occurs during the following week as the developing embryo reaches the uterus and nestles into the lining.
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.