Small U.S. firms borrowed slightly more in December than in the prior month, data released on Wednesday showed, but more were repaying existing loans late, suggesting that default rates may rise this year.

The Thomson Reuters/PayNet Small Business Lending Index rose to 129.7 in December from a downwardly revised 129.1 in November. Measured from a year earlier, when the index registered 135.6, it was the sixth decline in seven months. Movements in the index typically correspond with movements in gross domestic product growth a quarter or two ahead.

"It's an improved mood, but the questions are still out there on the policies and how they are going to play out," said Bill Phelan, PayNet's chief executive and founder, referring to policies under U.S. President Donald Trump, who was elected in November.

Since taking the top political U.S. post on Jan. 20, Trump has continued to meet with CEOs of big U.S. companies to urge them to boost jobs at home, and has signed a number of executive orders directing changes in immigration, health insurance, governments rule-writing and other policies that leave small businesses unclear on where they stand.

The U.S. economy grew at a 1.9 percent annual pace in the fourth quarter, the latest government figures showed, slower than in the third quarter but close to what many economists see as its long-term potential.

Small business borrowing is a key barometer of growth because small companies tend to do much of the hiring that drives economic gains.

"Small businesses are show-me kind of companies, and then they will get more active if they like the direction it's going," Phelan said.

Companies also having a harder time paying back existing debts, PayNet data showed. The share of loans more than 30 days past due rose in December to 1.69 percent, the highest in four years.

PayNet collects real-time loan information such as originations and delinquencies from more than 325 leading U.S. lenders.