UPDATE 1-National Oilwell Varco earnings top forecasts

* Earnings of $1.13 per share top forecast of $1.06

* Revenues rise to $3.48 billion

NEW YORK, April 23 (Reuters) - National Oilwell Varco Inc (NOV.N), an oilfield services company, on Thursday posted an 18 percent increase in first-quarter earnings as its strong backlog of orders offset cuts in spending from its energy-producing customers.

Net income for the first quarter rose to $470 million, or $1.13 per share, from $398 million, or $1.11 per share in the year-ago quarter.

Revenues rose to $3.48 billion from $2.69 billion.

Analysts had forecast earnings per share of $1.06, according to Reuters Estimates.

Shares in the company slipped 4 percent to $31.50 per share in pre-market trading. (Reporting by Matt Daily, editing by Gerald E. McCormick)