10 weeks!

From http://www.parents.com/:  "[Our] baby is still so tiny that he has plenty of room to move and groove in [Julie's] warm, protective amniotic fluid. He's now approaching 2 inches in length. If you could see him, you'd be pleased to note that his body is more in proportion; his head doesn't seem as large in comparison to the rest of him. You'd see that his ankles and wrists have formed, and his fingers and toes are now visible too.  An ultrasound taken now would probably show that the yolk sac is separate, and the umbilical cord from the placenta to [our] baby would be visible. [Our] baby's intestines are still part of the umbilical cord, but they're starting to move into his abdomen and will soon be covered by skin.  As for his organs, several more are starting to function. His thyroid gland -- the master switch for controlling his body's own unique chemistry -- is now operating. His pancreas is making digestive enzymes, and his gallbladder is secreting bile; these functions will be essential for eating and digesting his own food after birth.  [Our] baby's lung tissue is continuing to develop, and his bones are forming, even in his fingers and toes. Cells in the tiny hollows of his bones will soon start making blood cells, a function that until now has been the job of his liver and spleen. His face is starting to look more human; he may even have his first permanent tooth buds, and he will soon be able to open his mouth and move his tongue. It won't be long before he's sticking that adorable pink tongue out at [us]!"