* Wall St set for first monthly decline since August
* Mattel shares plunge after fourth-quarter results
* Futures down: S&P 14.5 pts; Dow 104 pts; Nasdaq 11.5 pts
NEW YORK, Jan 31 (Reuters) - U.S. stock index futures edged lower on Friday, setting Wall Street up for its first monthly decline since August, hurt by weaker-than-expected inflation data in the euro zone and ongoing concerns about turbulence in emerging markets.
* Eurostat's first reading of January inflation showed it slowed back down to 0.7 percent, raising pressure on the European Central Bank to consider fresh policy action to counter deflation risks and support a weak euro zone recovery.
* Ongoing concerns about the outlook for emerging markets have been pressuring global equity markets for weeks. The S&P 500 was now on track to end the month 2.9 percent lower. If the broad market index closes lower, the decline would be the biggest sine May 2012.
* Mattel Inc shares declined nearly 7 percent in premarket trade after the world's largest toy company's fourth quarter profit missed Wall Street's estimates.
* Amazon.com Inc shares also plunged nearly 7 percent in premarket trade, a day after the company missed Wall Street's estimates for the crucial holiday period and cautioned investors about a possible operating loss this quarter as shipping costs climb.
* S&P 500 e-mini futures fell 14.5 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 104 points and Nasdaq 100 futures fell 11.5 points.
* Google Inc's quarterly revenue beat Wall Street's target despite an ongoing decline in prices for its online ads and deepening losses at Motorola, the handset-making division to be sold to China's Lenovo. Google shares were up 3.2 percent in premarket trade.
* Zynga Inc shares rose nearly 17 percent in premarket trade after the company will shed 15 percent of its workforce to slash costs and buy mobile game developer NaturalMotion for $527 million to refresh a stalled games pipeline.