(Adds historical context for loss, share price, analyst comment)
BRASILIA, April 25 (Reuters) - Brazilian steelmaker Usiminas on Monday posted a loss of 151 million reais($42.5 million) in the first quarter, its seventh quarterly loss in a row, as the country's largest producer of flat steel struggles with a slump in demand and a severe recession.
Shares in Usinas Siderurgicas de Minas Gerais fell more than 8 percent in morning trade in Sao Paulo, but the stock is up more than 55 percent since January on a combination of hopes the steelmaker can turn itself around and rising steel prices.
Despite the loss, the company, which is in the midst of a boardroom battle between controlling shareholders, registered some slight improvements in comparison with the final quarter of last year.
First-quarter earnings before interest, taxes, depreciation and amortization (EBITDA) swung to a positive 52 million reais from a loss of 250 million reais in the fourth quarter.
EBITDA margins also improved into positive territory, reaching 2.5 percent in the first quarter compared with -10.4 percent in the prior quarter, partly due to the closure of its loss-making Cubatao steel mill.
The company also began exporting iron ore again, shipping 344,000 tonnes in the quarter, as it took advantage of a rise in the price of the steelmaking raw material.
Analysts at Citi said in a note the results were in line with their expectations and said focus will be on whether steel and iron ore prices hold up in the coming months. Citi rates Usiminas a sell.
$1 = 3.556 reais Reporting by Stephen Eisenhammer; Editing by Chizu Nomiyama and W Simon