American Home Products Corp. yesterday enriched its bid for A.H. Robins Co. by $100 million, topping offers by two rival drug manufacturers and winning the backing of Robins' outside shareholders. But the committee representing Dalkon Shield product-liability claimants said it will oppose the offer.

The New York-based conglomerate offered shares of American Home valued at $700 million, compared with $550 million only 20 days earlier -- an amount increased within days to $600 million. The offer would be a tax-free exchange for all of the stock of Richmond-based Robins.

American Home also improved its offer to women who claim injuries from the Dalkon Shield, the defective Robins intrauterine contraceptive device, while retaining the payout cap of $2.475 billion. The same cap was also accepted by the rival bidders, Sanofi S.A., of France, the merger partner chosen by Robins, and Rorer Group Inc. of Fort Washington, Pa.

U.S. District Judge Robert R. Merhige Jr., who presides in the 29-month-old Robins voluntary bankruptcy, has said that $2.475 billion, paid out over a reasonable period of time, would constitute full compensation of shield claimants.

American Home's proposed improvement is a commitment to pay the claimants $1.4 billion in the first two years and the balance over the four succeeding years, or, in the alternative, to pay $2.15 billion in cash at the closing. The alternative would enable interest to accrue for the benefit of the claimants. A contribution of undisclosed size, plus "certain insurance coverages," would be provided by Aetna Life & Casualty Co., which was the shield product-liability insurer.

By comparison, American Home's December proposal would pay out the $2.475 billion over seven years.

Murray Drabkin, counsel for the Dalkon Shield Claimants' Committee, said the American Home offer would "stretch out the payment" of shield claimants over six years, while providing "immediate payment to the shareholders and insiders of $700 million. This stands the Bankruptcy Code on its head. The Dalkon Shield victims are creditors. As such, they are entitled, as a matter of law, to be paid in full before shareholders receive anything. This proposal does not do that ... The Dalkon Shield problem is not going to be resolved by the ingenious use of financial discount tables."

Under the reorganization plan filed by Robins last Wednesday, Sanofi would acquire 58 percent of Robins for $600 million in the form of new convertible securities, and would pay the $2.475 billion to the claimants over a period of up to seven years.

The Sanofi bid has drawn criticism on the ground that it will retain the present Robins management at the expense of the outside shareholders.

The outside shareholders also have a critical say, because they control about 60 percent of the common stock. President E. Claiborne Robins Jr. and his family own the balance.

Robert M. Miller, counsel for the outside shareholders, said that the new proposal "represents the best offer for Robins' shareholders currently on the table."

It also offers "greater downside protection than the filed Sanofi plan," he said.

Bruce D. Fiedorek, managing director of mergers and acquisitions for Morgan Stanley & Co. Inc., which advised American Home, said his analysis of Sanofi's offer showed that it valued a Robins share at $15 to $20, compared with the $29 American Home offered yesterday.

H. Arvid Johnson, general counsel of Robins, told Dow Jones News Service, "It's interesting sitting here at a bankrupt company and seeing the bidding going up."

Robins reserved comment on the new bid, but Johnson said the board is "anxiously waiting to hear" from Sanofi.

A Sanofi spokesman said the company is studying the new bid but recalled vice chairman Jean-Francois Dehecq's comment last Thursday that Sanofi intends to "fight and win" the auction for Robins.

A Rorer spokesman said the company is "evaluating {the offer} and considering all our options."