The nation's two largest steel companies, U.S. Steel Corp. and Bethlehem Steel Corp., reported dismal first-quarter earnings yesterday, but agreed the prospect is brighter for the rest of 1978.

U.S. Steel, the No. 1 producer said it lost $58.7 million (70 cents a share) on sales of $2.46 billion while Bethlehem said it earned $1.1 million (2 cents) on sales of $1.4 billion.

Both companies said harsh winter weather and the 111-day Unted Mine Workers union strike against soft-coal operators were major factors in first-quarter results.

A year ago, U.S. Steel earned $27.4 million (33 cents) on sales of $2.27 billion, while Bethlehem reported a loss of $25.2 million (58 cents) on revenues of $1.3 billion.

Bethlehem said the coal strike cut pre-tax impact of $13 million when balanced against a $25 million inventory reduction during the strike.

"These severe strikes are behind us, and steel and nonsteel operations were profitable in March," said U.S. Steel Chairman Edgar Speer. "Production levels are recovering and, with coal flowing again, productive efficiency is returning to more acceptable levels."

Bethlehem Chairman Lewis Foy told shareholders at the company's annual meetng in Wilmington that new orders were strong due to improved demand from the construction industry.

Speer said U.S. Steel's bookings were at their highest level since August 1974, and he predicted the company's mills will operate at their highest level in four years during the second quarter.

The nation's biggest producer shipped 5 million tons during the first quarter up form 4.7 million a year ago, while Bethlehem said its shipments remained at about 3.1 million tons.

Both companies expressed concern over the high level of foreign steel imports during February. Imports totaled 2.3 million tons, or about 22 per cent of the domestic market in that month.

A Carter administration plan to curb alleged foreig steel dumping took effect in late February, and the domestic leaders said they looked for imports to decline in the second quarter.

"If imports do not begin to decline soon, we will have no choice but to pursue the remedies available to us under the trade laws," Foy warned.

Speer estimated that domestic shipments would reach 26 million tons during the second quarter. He projected U.S. consumption exceeding 1977 levels, which were the third best in history.

Procter & Gamble Co. net earnings for the first nine months of the fiscal year ended March 31 were $408.03 million ($4.94 a share), up 11 percent from the $366.48 million ($4.44) earned in the same period last year. Sales increased 10 percent to $6.036 billion.

Third-quarter earnings rose 12 percent to $147.11 million ($1.76) from $130.99 million ($1.59). Sales increased 13 percent to $2.174 billion.

P&G markets a wide range of household products, including soaps and detergents, toilet, goods, food products and paper products.

Eastern Airlines earned $19.5 million (92 cents a share) in the first quarter, up from $16.8 million (85 cents) a year ago. Revenues climbed 12.1 percent to $584.4 million.

Chairman Frank Borman told the annual meeting the gains resulted both from cost cutting and increased sales on improved services.

He also said Eastern hopes "to resume paying dividends as soon as we can responsibility do so." The airline has not paid any since 1969.

Eastern is working with the banks to remove a prohibition on dividends in the indenture in the airline's loan agreements.

Earnings and sales set records at Textron Inc. during its first quarter ended April 1 despite poor winter weather and the coal strike.

The conglomerate earned $39.8 million ($1.06 a share) on $727.2 million in sales compared with earnings a year ago of $28 million (75 cents) on $680.5 million in sales.

Textron's metal product group led an advance that included the consumer and creative capital groups. Aerospace group earnigs declined slightly, and industrial group earnings were flat.

Consolidated Edison Co. of New York, the large electric and gas utility, reported a modest increase in profits for the first quarter, but cautioned that results for all 1978 may fall below the previous year.

The company said profits were better than anticipated because of the colder-than-normal winter and te four-month coal strike, which ended last month.

For the first quarter, the utility registered a profit of $87.7 million ($1.41 a share) on sales of $814.7 million. For the comparable 1977 period, the company earned $84.2 million ($1.37) on sales of $797.5 million.