May 12 (Reuters) - U.S. stock index futures held on to their losses on Tuesday as investors assessed April inflation data and its impact on the Federal Reserve's monetary policy path.

A Labor Department report showed the Consumer Price Index rose 3.8% on a yearly basis in April, compared with estimates of a 3.7% increase, according to economists polled by Reuters. On a monthly basis, it rose 0.6%, in line with expectations.

Excluding volatile food and energy components, core CPI stood at 2.8% on an annual basis, compared with estimates of 2.7%. Core CPI stood at 0.4% on a month-on-month basis, versus a 0.3% expected rise.

At 08:37 a.m. ET, Dow E-minis YMcv1 were down 15 points, or 0.03%, Nasdaq 100 E-minis NQcv1 were down 224 points, or 0.76%, and S&P 500 E-minis EScv1 were down 24.5 points, or 0.33%.