The rotation of Earth is also slowing due to tidal friction from the Moon and other factors. Because of this, every so often a "leap second" has to be inserted into UTC to keep our clocks in sync with apparent time. Not all of the factors are currently understood, so there is no long term way to predict exactly when a leap second will need to be inserted.
However, there are occasionally long periods in which no leap second needs to be inserted (e.g. between 1999 and 2006). It appears we are currently in one of those periods. The last leap second was inserted on January 1st, 2017. According to IERS (International Earth Rotation and Reference System Service) Bulletin C Number 58 - issued July 4th, 2019 - there will be no leap second inserted for the rest of 2019.
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