ComScore today reported its numbers for smartphone subscribers in the U.S. for the three month period ending in April with Apple experiencing the biggest gains in both categories. The main theme of the report is much the same as we heard in its January and February reports– Apple is up and gaining while Android maintains its lead as top smartphone platform.

When it comes to market share by platform, comScore reports that Google continues its lead with 52.3% (down 0.3 percent since the January quarter), while Apple experienced a slight gain of 1.4 percentage points increasing from 37.8% to 39.2%. That’s compared to BlackBerry at just 5.1% (down from 5.9% last quarter) and 3.0% for Microsoft (down from 3.1%).

Apple also captured the biggest gain for smartphone subscribers by OEM, positioning itself as the No.1 smartphone vendor in the U.S. with 39.2% of the market compared to Samsung’s 22% during the three month period. Filling out the final three positions is HTC, Motorola, and LG:

138.5 million people in the U.S. owned smartphones (58 percent mobile market penetration) during the three months ending in April, up 7 percent since January. Apple ranked as the top OEM with 39.2 percent of U.S. smartphone subscribers (up 1.4 percentage points from January). Samsung ranked second with 22 percent market share (up 0.6 percentage points), followed by HTC with 8.9 percent, Motorola with 8.3 percent and LG with 6.7 percent.

Unlike some other reports that often includes shipments of devices, comScore tracks mobile phone usage through its MobiLens data surveys.