The end of week 10 is the end of the embryonic period and marks the beginning of the fetal period. Most congenital defects occur before the end of week 10. The critical part of your baby's development is safely behind you. Few malformations occur during the fetal period. However it is still advisable to avoid severe stress or radiation. The tubes in your baby's lungs are fully formed and his intestines have migrated from the umbilical cord into the abdominal cavity. Your baby's taste buds start to develop and if your baby is a girl, her ovaries start to descend into the pelvis. Your baby is still very lightweight and measures about 1Â½ to 1Â¾ inch long 3.1-4.2cm and weighs close to just 1/30th of an oz or 0.18 oz (5g).