Week 5 of pregnancy
How your baby is developing
- The neural tube — which will become the brain and spinal cord — begins to form.UNSW Embryology (CC-BY)
- A primitive heart structure begins to develop and will soon start beating.UNSW Embryology (CC-BY)
How you may feel
- A missed period is often the first clear sign; nausea and fatigue commonly begin.NHS
- Needing to urinate more often is common as hormone levels rise.NHS
Nutrition this week
- Folate (B9) — supports neural-tube closure — most critical in weeks 1–12 (Leafy greens)
- Iodine — fetal brain + thyroid development (Iodized salt)
- Vitamin B12 — with folate, for blood + nerves (Meat)
When to reach out
- Heavy vaginal bleeding or passing clots.ACOG
- Severe or persistent abdominal or pelvic pain.ACOG
- Severe, persistent nausea or vomiting that prevents keeping any fluids down (possible hyperemesis gravidarum).NHS
- Fever of 38°C (100.4°F) or higher, or chills.WHO
- Severe dizziness, fainting, or a racing/irregular heartbeat.NHS
- Pain or burning when urinating (possible urinary tract infection).NHS
These apply to this week specifically. See the full list of urgent warning signs the CDC publishes for pregnancy and the year after birth.
Part of the First trimester (weeks 1–13).
Educational reference only — not medical advice. Typical/average figures; every pregnancy differs. Always consult your doctor or midwife. Seek urgent care for any warning sign.