(Telecompaper) Global shipments of branded tablets, excluding e-readers and convertible PCs, rose 117 percent to 40.6 million units in the first quarter, compared to 18.7 million in the year-earlier period, according to Strategy Analytics. Apple shipped 19.5 million iPads, compared to 11.8 million in the first quarter of 2012, maintaining its market share leadership with 48.2 percent in the first quarter, compared to 63.1 percent in the year-earlier first quarter. Shipments of branded tablets running Android rose to 17.6 million units (43.4 percent share) from 6.4 million units (34.2%). Windows tablet shipments reached 3 million units for a 7.5 percent market share in the first quarter. There were no Windows tablets a year ago. Microsoft's tablet shipments are being held back by very limited distribution, a shortage of top-tier apps and market confusion, according to the market researcher. Including white box tablets, Android had a 52 percent share of all tablets shipped, ahead of Apple with 41 percent.