Bright Grey and Scottish Provident are remaining defiant and calling government action in the face of the European Court of Justice (ECJ) decision to ban gender based underwriting.
The ABI added that it was disappointed with the ruling that outlawed the practice from 21 December 2012 and hoped customers would not be put off by it.
Fears had been raised that the judgment could have been introduced immediately and, in a worst case scenario, enacted retrospectively.
This could have resulted in a chaotic period as some providers removed products to update underwriting systems while a mass re-pricing took place as the market sought to find the correct level for risk pricing.
Roger Edwards, proposition director of Bright Grey and Scottish Provident, told COVER he was thankful for the transition period but disappointed the practice had been banned.
"It undermines the insurance principles that have been in place for hundreds of years and I just do not believe its discrimination in the politically correct sense that the ECJ have judged it to be, but we're going to have to comply with that," he said.
"If it had happened today there would have been a real flurry of activity for next month so would causing quite a lot of chaos and a lot of uncertainty, but it would've got it out of the way.
"Eighteen months is quite a long time but we should be looking for what are potential alternatives for this," he added.
Edwards acknowledged he was unsure of the full legal implications of the ruling but demand government and the ABI pull out all the stops to achieve a re-think.
"The ABI and government stance was not to rock the boat because if we did it would make the decision a certainty," he explained.
"Well that non-vocal stance obviously didn't help so do we use next 18 months to lobby government and use the industry to find another way of over turning the decision. We should leave no stone unturned to try and find a possible solution because it's the wrong decision.
"I'm all for equality but this isn't discrimination its just pricing and its common sense," he added.
Edwards view was partially supported by the ABI which noted that over the next 20 months insurers would have large scale changes to make including amending all affected policy documentation, contacting customers, updating computer systems and ensuring intermediaries have the right information.
Maggie Craig, acting director general of the ABI, said: "This gender ban is disappointing news for consumers and something the UK insurance industry has fought against for the last decade.
"The judgment ignores the fact that taking a person's gender into account, where relevant to the risk, enables men and women alike to get a more accurate price for their insurance.
"It will be crucial to ensure this news does not put people off having vital insurance that protects them against accident or illness, or provides an income in retirement. Each company will have to respond to the ban in the way they feel is in their customers' interests.
"Adaptation during this transition period will be challenging, but all insurers will be doing everything they can to ensure as smooth a change as possible for customers," she added.
