Stock index futures added gains on Tuesday after data showed U.S. housing starts fell slightly less than expected in February, while a decline in U.S. import prices was largely in line with expectations.

* S&P 500 futures rose 2.70 points and were above 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 gained 12 points and Nasdaq 100 futures added 5 points.

(Reporting by Leah Schnurr)