The embryo is now about half a centimeter long (around 2-3mm), roughly the size of a sesame seed. A flurry of development is happening within this tiny being! The heart, a vital organ, has begun to beat, although it may be irregular at this early stage. This tiny heartbeat is a powerful sign of the life growing within you. Major organs are starting their formation journey. The liver and kidneys, crucial for filtering waste and other functions, are beginning to develop. Even facial features are starting to take shape – the nostrils, mouth, and eyes are beginning to bud. The placenta and the umbilical cord, lifelines for your baby, are also developing rapidly. These structures will act as a channel, delivering essential nutrients and oxygen from your body to the embryo. Oxygen, amino acids, fats, and sugars are all vital building blocks for your baby's growth and development. The neural tube, which will eventually become the spinal cord and brain, is forming. This is a critical stage in neurological development. The amniotic sac, which will cushion and protect your baby throughout pregnancy, is also forming. Your baby is now officially called an embryo. Key Developments: Baby's neural tube forms, heart begins to form (and beats!), and blood begins to circulate. The liver begins to function. Facial features start to emerge. Placenta and umbilical cord begin to develop. Size: Approximately 2-3 mm (half a centimeter).