(Reuters) -U.S. stock index futures rose on Wednesday as megacap growth stocks offered support, while a flurry of corporate earnings and commentary from Federal Reserve policymakers also caught investors' attention for cues on the health of the economy.

Megacap growth names such as Microsoft, Amazon.com and Tesla advanced between 0.5% and 1.1% before the bell.

The benchmark S&P 500 and the Nasdaq closed lower in the previous session, bogged down by climbing Treasury yields.

Government bond yields eased slightly, with the 10-year note last at 4.6469%.

Fed Board Governor Michelle Bowman and Cleveland Fed President Loretta Mester are scheduled to speak later in the day.

Top U.S. central bank officials including Fed Chair Jerome Powell refrained from providing any guidance on when interest rates may be cut. On Tuesday, they said monetary policy needed to be restrictive for longer, dashing investors' hopes for meaningful reductions in borrowing costs this year.

"While stopping short of mentioning rate hikes, Chairman Powell on Tuesday highlighted that 'the recent data have not given greater confidence in inflation'," Achilleas Georgolopoulos, investment analyst at forex broker XM said in a note.

"With Vice Chairman Jefferson indirectly stating that rate cuts could be a long way off, Bowman and Mester could also appear hawkish today and potentially inflict further damage to market sentiment amidst a very light US data calendar."

Money market participants see an around 43% chance the central bank could begin its easing cycle in July, as per the CME FedWatch tool.

Later in the day, investors will watch for the Fed's release of the "Beige Book" report, to assess the state of the world's largest economy.

At 7:12 a.m. ET, Dow e-minis were up 135 points, or 0.35%, S&P 500 e-minis were up 21.25 points, or 0.42%, and Nasdaq 100 e-minis were up 53 points, or 0.30%.

Among headlining stocks, United Airlines gained 5.2% after forecasting stronger-than-expected earnings in the current quarter.

Other airline stocks such as American Airlines, Delta Air Lines and Southwest Airlines added between 0.9% and 1.8%.

Mobileye advanced 3.1% after Reuters reported the Israeli automotive tech company was set to ship at least 46 million new assisted-driving chips.

JB Hunt Transport Services dipped 7.9% after the trucking firm missed Wall Street estimates for first-quarter results.

Apparel retailer Urban Outfitters fell 5.3% after Jefferies downgraded its rating to "underperform" from "hold".