Except for infants. Right now a child up to 2 can be held on a lap. Under this policy, families would now be paying for the baby (born and unborn - pregnant women would be charged more too).
I called the airline talked to an American got the addition done in about 2 minutes on the phone. Six months later, same deal, still United, called and was transferred to a call center in India. It took literally 25 minute on the phone and they still screwed it up. They added the baby on for only two of the three legs.