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
about the size of a poppy seed
0.1 inches · less than 1 oz
Baby this week
- •Blastocyst has just implanted in your uterine lining
- •Cell division is happening rapidly
- •The amniotic sac is beginning to form
- •Primitive placenta is starting to develop
You this week
- •Missed period (the main clue you might be pregnant)
- •Breast tenderness and sensitivity
- •Mild cramping or lower abdominal discomfort
- •Fatigue and increased need for sleep
- •Nausea may be starting or about to begin
- •Mood swings from hormonal changes
- •Frequent urination
This week's tips
- •Take a pregnancy test if you haven't already—many are accurate from the first day of a missed period
- •Schedule an appointment with your healthcare provider to confirm the pregnancy and establish prenatal care
- •Start taking prenatal vitamins with folic acid if you haven't already (folic acid is crucial for preventing neural tube defects)
- •Avoid alcohol, smoking, and recreational drugs
- •Be gentle with yourself—rest when you need to and don't push through exhaustion
- •Keep a food and symptom journal if you're experiencing nausea
Informational only — always check with your doctor or midwife for advice specific to you and your baby.
Looking ahead
Next week, your baby's heart will begin to beat, and you'll move into week 5—often called the 'official' start of pregnancy in many care models. Your hormone levels will continue rising, which may intensify early pregnancy symptoms.
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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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