The figure is better than the 7% decrease reported in August and included a 5% increase in December, although this performance was helped by comparisons with the cold snap the previous Christmas.
Total global sales were down by 1.2% despite a 3% increase in its worldwide network. Mothercare has 1,000 stores outside the UK.
The update is unlikely to relieve the pressure on the UK business following a poor 2011, which saw it place its entire UK business under review after half-year losses of more than £80 million and the departure of chief executive Ben Gordon.
Executive chairman Alan Parker said: “In the UK, the better like-for-like sales performance was achieved in an increasingly competitive consumer environment.
“Additional promotional activity was successful in driving a 5% like-for-like sales increase in December.”