Week 4 of Pregnancy
First trimester
Baby is
about the size of a poppy seed
0.1 inches · less than 1 gram
Baby this week
- •Blastocyst has implanted into the uterine wall
- •Cell division is rapidly accelerating
- •Amniotic sac is beginning to form
- •Placenta development is starting
You this week
- •Missed period
- •Breast tenderness and swelling
- •Mild cramping or spotting (can be normal)
- •Fatigue and increased need for sleep
- •Nausea may begin for some
- •Heightened sense of smell
- •Mood swings
This week's tips
- •Take a pregnancy test if you haven't already—it's most accurate after a missed period
- •Schedule your first prenatal appointment to confirm pregnancy and establish care
- •Start taking prenatal vitamins with folic acid if you haven't already
- •Be gentle with yourself; fatigue is normal as your body adjusts
- •Avoid alcohol, smoking, and unnecessary medications
- •Stay hydrated and eat nourishing foods when you can tolerate them
Looking ahead
Next week marks the official start of week 5, when your baby's heartbeat may become detectable on ultrasound. This is also when many pregnancy symptoms tend to intensify as hormone levels rise.
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