Your baby this week

Fertilization usually happens now. A single cell forms. It starts dividing fast.

By the end of the week, that ball of cells usually reaches your uterus (womb).

You this week

It's usually too early to feel symptoms. The pregnancy hormone hCG hasn't risen enough yet.

Week 3 of pregnancy

How your baby is developing

  • Fertilization typically occurs this week; the resulting single cell begins dividing rapidly as it travels toward the uterus.UNSW Embryology (CC-BY)
  • By the end of the week, a small ball of dividing cells (the blastocyst) typically reaches the uterus and prepares to implant.UNSW Embryology (CC-BY)

How you may feel

  • It's typically too early for pregnancy symptoms; hCG hormone has usually not yet risen enough to detect.ACOG

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)

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.

Tips for this stage

  • Continue folic acid — this is the most critical window for neural tube developmentSource: NHS – Vitamins, supplements and nutrition in pregnancy; CDC – Folic Acid
  • Light, home-cooked mealsSource: NHS – Have a healthy diet in pregnancy
  • Avoid raw/undercooked food and unpasteurised dairy as a precautionSource: NHS – Foods to avoid in pregnancy
  • Limit caffeine to under 200mg/daySource: NHS – Foods to avoid in pregnancy

Checklist

  • It's usually too early for a home pregnancy test to detect hCG yetSource: NHS Start4Life — Week 4 of pregnancy
  • Continue folic acid without interruptionSource: NHS – Vitamins, supplements and nutrition in pregnancy; CDC – Folic Acid
  • Note any early spotting (implantation bleeding is common and usually harmless, but track it)Source: NHS-affiliated Trust patient information — Bleeding in early pregnancy