Edinburgh handled a total of 767,500 passengers, a fall of 1.1% on the same period last year.
Last month, the airport was sold to the owner of Gatwick and London City airports for £807m.
Aberdeen's passenger traffic climbed by 11%, while Glasgow recorded a 6.7% increase.
BAA said Aberdeen's increase reflected strong energy-related traffic.
Almost 550,000 people travelled through Glasgow in April, as the airport reported an increase in demand for both international and domestic travel.
The airport has succeeded in adding a number of new routes in recent months, including direct flights to Barcelona, Rome and Venice.
Glasgow Airport managing director Amanda McMillan said: "Despite the challenges presented by rising fuel costs and further increases in Air Passenger Duty (APD), we have enjoyed considerable success in expanding our route network and this has been a major factor in encouraging more people to fly from Glasgow Airport."
In April, Global Infrastructure Partners (GIP) beat off competition to buy Edinburgh Airport.
It was put on the market by owner BAA last October, after the Competition Commission ruled that it had to sell either Edinburgh or Glasgow.
The winning price, expected to be paid at the end of May, was considerably more than had been expected.