Southwestern Bell Corp. reported yesterday that its net income for the first quarter of 1985 increased 29 percent over the same period a year ago. Earlier, Pacific Telesis Group, another of the seven regional Bell holding companies, reported profits of 13 percent, but U S West Inc. said its earnings declined.

GTE Corp. said its first-quarter profit fell 14.3 percent to $273 million ($1.29 a share), from $312 million ($1.59) a year ago.

U S West blamed an out-of-court settlement in an antitrust suit for a decline in its earnings for the first three months of 1985. GTE said it would have had a 2 percent profit gain if a special one-time credit were excluded from its 1984 results.

In other earnings reports yesterday, Manufacturers Hanover Corp., the nation's fourth-largest bank holding company, said yesterday that its first-quarter profit rose 19.3 percent.

Coca-Cola Co., the nation's leading soft drink manufacturer, said its first-quarter profit edged up 2.3 percent, including strong gains in both its soft drink business and its entertainment division.

* Southwestern Bell Corp., based in St. Louis, reported net income of $264.6 million ($2.66 a share), compared with $205 million ($2.12) last year.

Revenue was $1.9 billion vs. $1.7 billion.

Zane Barnes, chairman and chief executive officer of Southwestern Bell, said revenue increased because of a steady rise in the number of customers. He also cited federal regulations that increased access charges paid to Southwestern Bell by long-distance companies.

During the first quarter of 1985, the company's expenses were $1.37 billion, compared with $1.25 billion a year earlier.

* Pacific Telesis Group, based in San Francisco, reported a first-quarter profit of $223.5 million ($2.23 a share), compared with $196.8 million ($2.04) a year ago.

Its revenue rose to $2.05 billion from $1.86 billion a year ago.

"While our revenues have increased, our long-term expense control programs continue to be an important element in increasing the return on our shareowners' investment," said Donald Guinn, Pacific Telesis chairman and chief executive.

* GTE Corp., which is based in Stamford, Conn., said its 1984 results were boosted by $45 million because of an accounting change involving investment tax credits of non-telephone operations.

Without that one-time gain, the company said its profit would have been $267 million ($1.36 a share) a year ago.

Its revenue rose 6 percent to $3.7 billion from $3.4 billion.

GTE Chairman Theodore F. Brophy said strong showings by local telephone and electrical products divisions more than offset declines in the Sprint long-distance telephone business and in communications products.

* U S West, the Denver-based regional company that owns Northwestern Bell, Mountain Bell and Pacific Northwest Bell telephone companies, said its first-quarter profit fell 3 percent to $197.4 million ($2.05 per share), compared with $202.6 million ($2.10) a year earlier.

Revenue rose 9 percent to $1.9 billion from $1.7 billion a year earlier.

The company's results were lowered, officials said, by last month's out-of-court agreement with MCI Communications Corp., which ended a longstanding antitrust action unvolving U S West and its three telephone operating subsidiaries.

* Manufacturers Hanover Corp., based in New York and parent to the No. 4 bank in the country, Manufacturers Hanover Trust Co., said its first-quarter income rose to $100.2 million ($2.01 a share), from $84.0 million ($1.88) a year ago.

The change in per-share earnings was not as large as the overall earnings gain because of dividend requirements on preferred stock issued last May and new common stock issued last February in connection with the acquisition of CIT Financial Corp.

Total assets on March 31 were $72.8 billion compared with $64.8 billion a year ago.

* Atlanta-based Coca-Cola Co. posted net income of $141.2 million ($1.08 per share), compared with $138 million ($1.02) for the same quarter in 1984.

Net operating revenue rose 11.2 percent to $1.76 billion from $1.58 billion in the same period in 1984.

Roberto C. Goizueta, chairman of the board and chief executive of the company, said unit volume in its soft drink operations outside North America increased an average of 8 percent during the quarter, including a 15 percent volume increase in Europe and Africa.

Coca-Cola USA achieved an 8 percent increase in syrup and concentrate shipments.