Pregnancy Week by Week · First Trimester
Pregnancy Week 5: Your Baby's Heart Begins
A sesame seed with a heartbeat — that's your baby this week. Week 5 is small on the outside and monumental on the inside: a tiny heart is beginning, the brain and spine are under construction, and the first wave of symptoms may be checking in. Here's your calm, complete guide.
Baby's sizeA sesame seed
MilestoneThe heart begins to beat
Also formingNeural tube → brain & spine
TrimesterFirst
Week 5 of 40 — you're 12.5% of the way there, mama 🌸
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Watch this week's video
This week's video — Pregnancy Week 5: Your Baby's Heart Begins — is already live on our YouTube channel, together with the whole week-by-week series.
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Your baby this week
Your baby is about the size of a sesame seed. The headline event: the heart tube forms and begins its very first beats — not yet the steady rhythm you'll hear at an ultrasound, but the beginning of it. At the same time, the neural tube is forming along your baby's back; over the coming weeks it becomes the brain and spinal cord. The basic body plan — head end, tail end, the curve of a tiny body — is taking shape.
Your body & symptoms: the first wave arrives
This is often the week symptoms check in: tender breasts, a tiredness that naps don't fix, more trips to the bathroom, a heightened sense of smell, and for many moms the first queasiness. Some moms still feel nothing at all — both experiences are completely normal at week 5.
The neural tube & why folic acid matters now
The neural tube closes in these very early weeks — often before women even know they're pregnant — which is why folic acid is recommended before conception and through the first trimester. It significantly reduces the risk of neural tube defects. If you haven't started, start today; you're still in the window where it matters most.
Choosing your doctor & booking your first visit
Decide who will care for you — an OB-GYN, a midwife, or your family doctor, depending on your health and where you plan to give birth — and book the first prenatal visit, usually scheduled for around weeks 8–10. Write down your questions as they occur to you; no question is too small.
⚠️ Warning signs — call your doctor the same day
Heavy bleeding · severe or worsening pain · pain on one side · fainting · vomiting so much you can't keep fluids down. If something feels wrong, making the call is always the right move.
✅ Mama checklist — Week 5
- Start folic acid today if you haven't yet — the neural tube is closing in these very weeks
- Choose your doctor or midwife and book your first prenatal visit (usually around weeks 8–10)
- Keep a running list of questions for that visit — no question is too small
- Rest without guilt: a tiredness that naps don't fix is a classic week 5 symptom
Key takeaways
- Your baby's heart tube is beginning its first beats; the neural tube is forming
- Folic acid matters most right now, while the neural tube is closing
- The first wave of symptoms is normal — and so is feeling nothing yet
- Choose your doctor and book your first prenatal visit (usually weeks 8–10)
Prefer reading on the blog? This guide also lives on the Bump & Bloom blog →
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General information only, not medical advice. Always follow your own doctor or midwife for personal care.