Your baby's organs have been finished forming for a long time. Now is the time for finishing touches. For example, the lungs make final preparations for birth by secreting surfactant to help them expand at birth. Your baby's kidneys are still producing lots of urine every day, helping to make up the almost two pints of amniotic fluid. While your baby may be putting on half a pound a week up until about week 37 at which point weight gain slows drastically. The average birth weight is still about seven and a half pounds. Your baby will measure between 18-22 inches at birth. Your due date is a guess as to when your baby may arrive. The majority of babies will show up from two weeks before this date to two weeks after this date. Labour is caused by the baby's signals to the mother's body that he or she is ready to be born. Good luck and good birth!