The weaker U.S. economy has led to a five-year low in the number of venture-backed businesses going public, according to the National Venture Capital Association.

There were just five venture-backed IPO over the first quarter, which together raised $282.7 million, the trade group reported this week. Businesses in the life sciences sector accounted for more than $220 million in total IPO proceeds for the quarter, including an $83 million deal by IPC The Hospitalist Company, Inc., a California-based hospitalized patient-care firm.

For the first time in eight years, there were no foreign IPOs on U.S. exchanges.

Mark Heesen, the group's president, blamed the declines on economic uncertainties.

"It was not a great start to the year by any measure and we will need to see a significant increase in volume in the remaining three quarters to salvage the rest of the year," Heesen said in a statement.

The number of mergers and acquisitions has also dropped to a six-year low, the group reported.