Please spend the money and buy the baby a seat. It will much more pleasant for you and MUCH SAFER. Too many stories of infants in mother's arms that have been seriously injured(or worse) as the baby flew out of parents arms during extreme turbulence and even God forbid an emergency landing. There was a whole article in our local newspaper a number of years back about this issue. They explained that in case of an emergency a baby must be left on the floor as the parents take the "brace" position or make the decision to hold the baby. Holding the baby takes the chance of you squashiing the baby with your body wait and putting the baby down can allow the baby to fly around the plane . Of course this is such a rarity, but after I read this I never took my children on the plane without a ticket. It is an expense but in the long run, its worth it.