Quick answer: Week 5: Neural tube forms, sickness triggers & relief tips, foods to eat & avoid.
You’ve reached week 5 and you’re in the thick of the first trimester — the most physically demanding stretch for many women. The work your body is doing right now is extraordinary, even if it’s invisible from the outside.
Baby Development This Week
At week 5, your baby is approximately the size of a sesame seed — measuring around 0.13 in / 3mm. The neural tube is closing. The heart begins beating around day 22. All major organ systems are forming at extraordinary speed.
Symptoms You May Feel
Week 5 first trimester symptoms typically include: nausea (often worst between weeks 6–10 and frequently striking at all hours despite the ‘morning’ misnomer), profound fatigue driven by surging progesterone, breast tenderness and fullness, frequent urination as kidneys filter increased blood volume, food aversions and cravings, a heightened sense of smell that amplifies nausea, bloating, and mood swings from rapidly shifting hormones. Not every woman experiences all of these — some have almost no symptoms through the first trimester and that is completely normal.
Neural tube forms, sickness triggers & relief tips, foods to eat & avoid
At week 5, the neural tube is actively closing — this is the process that forms the brain and spinal cord. Folic acid is critical during this window, which is why starting prenatal vitamins before conception is recommended. The embryo is approximately 3mm; the heart has begun beating as a simple tube structure (though it won’t be detectable on ultrasound for another week). Morning sickness at week 5 is driven by rapidly rising hCG and progesterone — it typically peaks around weeks 8–10. Foods to prioritize: protein (stabilizes blood sugar), B6-rich foods (bananas, potatoes, poultry), and ginger for nausea relief.
Practical Tips for Week 5
- Take your prenatal vitamin daily. At week 5, the neural tube is actively closing — folic acid (400–800mcg) is essential right now. If you aren’t already taking a prenatal, start immediately.
- Eat small meals every 2–3 hours to keep nausea at bay — an empty stomach makes symptoms worse.
- Ginger tea, ginger capsules (250mg 4x daily), and Vitamin B6 (25mg 3x daily) have solid evidence for nausea.
- Rest is not laziness — your body is doing extraordinary work. Nap when you can.
- Avoid alcohol completely. Limit caffeine to under 200mg daily (roughly one 12oz coffee).
- Book your first prenatal appointment if you haven’t yet — the initial visit is typically at 8–10 weeks.
When to Call Your Midwife or OB
Call your provider immediately for: heavy bleeding (soaking a pad), severe one-sided abdominal pain (possible ectopic sign), fever above 101°F / 38.3°C, inability to keep any fluids down for 24+ hours, or any symptom that feels wrong to you.
Frequently Asked Questions
Is it normal to have no symptoms at 5 weeks pregnant?
Yes — many women with perfectly healthy pregnancies experience minimal or no nausea, fatigue, or breast tenderness. Symptom severity is driven by your individual hormone levels and sensitivity, not by pregnancy health. A day of feeling ‘almost normal’ doesn’t mean anything is wrong. At 5 weeks, most women haven’t had an ultrasound yet — a positive pregnancy test is the confirmation you have. Ultrasound at 5 weeks may show a gestational sac but often cannot yet detect cardiac activity. If your OB has scheduled an early scan, it’s typically at 6–8 weeks when a heartbeat is reliably detectable.
When will I start showing at week 5?
First-time mothers typically develop a visible bump between weeks 12–16. Before that, bloating can make the belly look larger, but the uterus is still tucked low in the pelvis. Women who’ve been pregnant before often show earlier because uterine muscles are already stretched. Height, body type, and position of the uterus all affect when you show.
Can I exercise during the first trimester?
Yes — for most healthy pregnancies, moderate exercise is safe and beneficial throughout the first trimester. Walking, swimming, and prenatal yoga are excellent options. Avoid contact sports, high-fall-risk activities, exercises lying flat on your back for long periods, and hot yoga. If you were active before pregnancy, you can usually continue your routine with modifications as your body feels comfortable.
Disclosure: This post contains affiliate links. We may earn a small commission at no extra cost to you. We only recommend products we genuinely trust.
Related Reading
- Weaning meal plan: 4-week starter guide for 6-month olds
- First baby purees: 15 easy recipes for 4-6 month olds
Found this helpful? Sign up to the LylyMama newsletter for evidence-based guides, honest essays and practical advice delivered to your inbox every week.
