Your baby
At 4 weeks, the cluster of cells that will become your baby is burrowing into the lining of your uterus and beginning to form the placenta and amniotic sac. Though no bigger than a poppy seed, the embryo is already organizing into layers that will become the brain, spine, heart, and digestive system. The outer layer of cells is beginning to form the placenta, the organ that will take over delivering oxygen and nutrients to your baby in the weeks ahead.
Your body
You may have just missed your period or seen a positive test, and many people feel nothing different yet. Early signs can include light spotting as implantation happens, mild cramping, tender breasts, or fatigue. If you do not have symptoms, that is completely normal and not a cause for worry.
This week
Start a daily prenatal vitamin with folic acid if you have not already, since it supports your baby's neural development right now. Call your OB/GYN to schedule your first prenatal visit, and begin avoiding alcohol, smoking, and unpasteurized foods. Be gentle with yourself as your body begins this big work.
Try our baby size tool, due date calculator, and food safety checker, and book your prenatal care with Garden OB/GYN across Brooklyn, NYC, and Long Island.
Book your prenatal visitAbout this guide
This page is general educational information, compiled from publicly available guidance from trusted medical sources, including the NHS and MedlinePlus. It is not medical advice from Garden OB/GYN or its providers, and it is not a substitute for care from your own clinician. Every pregnancy is different, so always talk with your OB/GYN about your specific situation. See our full medical disclaimer.
