Week 4 of Pregnancy
First trimester
For informational purposes only. This page is not medical advice. Every pregnancy is different — always consult your doctor, midwife, or healthcare provider for guidance specific to your situation. In an emergency, call your provider or 911 immediately.
Baby is
a poppy seed
0.1 inches · less than 1 gram
Baby this week
- •Blastocyst is implanting into the uterine lining
- •Cell division is rapidly accelerating
- •The amniotic sac is beginning to form
- •Placenta development has started
You this week
- •Missed period (often the first sign you notice)
- •Breast tenderness and swelling
- •Mild cramping or spotting as the blastocyst implants
- •Fatigue and needing extra rest
- •Nausea may begin to appear for some
This week's tips
- •Take a pregnancy test if you've missed your period—early detection tests work best with first morning urine
- •Schedule an appointment with your healthcare provider to confirm pregnancy and discuss prenatal care
- •Start taking prenatal vitamins with folic acid if you haven't already; this supports baby's neural tube development
- •Be gentle with yourself—exhaustion is real and normal right now
- •Avoid alcohol, smoking, and discuss any medications with your doctor
Informational only — always check with your doctor or midwife for advice specific to you and your baby.
Looking ahead
By week 5, your baby will be officially considered an embryo, and you may hear a heartbeat at your first ultrasound. The next few weeks bring rapid growth and the beginning of major organ formation.
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For informational purposes only. This page is not medical advice. Every pregnancy is different — always consult your doctor, midwife, or healthcare provider for guidance specific to your situation. In an emergency, call your provider or 911 immediately.
This content is for informational purposes only and is not medical advice. Every pregnancy and baby is different. Always consult your doctor, midwife, or pediatrician for guidance specific to your situation.
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