Fetal development progresses through three main stages: Germinal (Weeks 1-2), from fertilization to implantation; Embryonic (Weeks 3-8), when major organs and body structures form rapidly (heart beats, brain develops); and Fetal (Week 9 to Birth), a period of significant growth, refinement, and maturation, with milestones like feeling movement (around 16-20 weeks) and developing senses. Key milestones include the neural tube forming (Week 5), heart starting to beat (Week 6), webbed fingers/toes