| | Family Health | Babies Health How big is the baby after 3 weeks? The average baby is about 1 inch (2.5 cm) long and weighs about 1/28 ounce (1 gram) at 3 weeks after conception. Babies Health - Related Articles What Is the Difference Between HDL & LDL? How to Repair a Dawn Simulator How to Lose Dandruff Is there an alcohol rehab center in Charlotte? Why do people need psychologist to help them with their needs? Can you get 360 waves if have dandruff? Theory of Anxiety