The euro extended earlier losses on Thursday, falling to three-month lows against the dollar as the U.S. currency made gains across the board ahead of U.S. retail sales data. Data at 1230 GMT is forecast to show retail sales up 0.7 percent in April, and traders were looking to a strong reading after data on Thursday showing an unexpected narrowing in the U.S. trade deficit in March. "After the trade data, people are saying there will be an upward revision to Q1 GDP and the dollar is likely to remain supported by retail sales later," said Kamal Sharma, currency strategist at Dresdner Kleinwort Wasserstein. The euro fell a third of a percent on the day to $1.2757 its worst showing since February 10. The dollar also rose half a percent against the Swiss franc to four-week highs of 1.2124 francs, and approached three-week highs against the yen .