July 21 (Reuters) - Domino's Pizza surpassed analysts' expectations for second-quarter U.S. same-store sales on Monday, driven by new items on the menu and promotions, amid persisting macroeconomic uncertainties.

The shares gained 1.9% in premarket trading.

The world's largest pizza chain added items such as the parmesan-stuffed crust pizza to its list, and attracted value-conscious consumers through deals under its rewards program. That partly helped cushion the impact from U.S. President Donald Trump's on-and-off tariff policy and the ensuing trade war.

"In the U.S., both delivery and carryout grew, driving meaningful market share gains," Domino's CEO Russell Weiner said.

Domino's posted a 3.4% rise in same-store sales in the U.S. for the quarter ended June 15, exceeding analysts' average estimate of a 2.21% rise, according to data compiled by LSEG. That marked its first beat in five quarters.

The company's online sales also grew, helped by discounts and from the success of its partnership with DoorDash, which doubled its share of sales made through third-party delivery channels to roughly 5%, according to Matt Goodman, analyst at research firm M Science.

International same-store sales grew 2.4%, also ahead of the estimate of 1.71% growth.

The company posted earnings per share of $3.81, compared with the estimate of $3.95.