As part of several enhancements to its Life Insurance Plus and Critical Illness Plus products, the insurer has doubled the maximum benefit payable where upgraded children's benefit has been selected when taking out an adult policy.
The enhancements also include improving the definitions for heart conditions, strokes and cancers.
For conditions such as spinal strokes, for example, the changes to the definitions will mean Aviva can pay out at an earlier point following diagnosis.
For cardiomyopathy, the broadening of the definition to include three measures of severity means more customers with a diagnosis of the condition will meet the description under which the insurer can make a payment.
Having a plan specifically designed to cover children would be a major advancement.Garry Webb
Mark Cracknell, head of protection distribution for Aviva, said: "What we are trying to do with this is to provide the best possible critical illness proposition to advisers.
"Critical illness can get too complicated as definitions become more complex, which makes the adviser's job difficult. So it is important to improve the clarity and consistency of definitions.
"Also, in terms of underwriting, we want to pay out the highest proportion of claims we can. The critical illness market is evolving and we recognise that childhood cancer is a serious issue.
"But as medical advancements mean people can get a diagnosis earlier, this is leading to an increase in claims.
"Therefore the extra care cover we have on this this can provide a family with a larger and more meaningful lump sum."
The industry average is £25,000 for a child up to 21 or 22, depending on certain providers.
While this sounds like a lot of money as a lump-sum, it can soon be eroded if one adult has to give up work and become a full-time carer, or there are other children.
Mr Cracknell said the 100 per cent uplift in the cover reflected the reality of rising medical costs, as well as the fact "life doesn't stop" for families.
Earlier this month, Aegon stressed the need for parents to check whether they had cover for children embedded within their own critical illness policies.
According to Aegon, of all the critical illness claims received by the company over the past 10 years, 67 per cent were for children's cancer.
In 2016 alone, cancer accounted for 81 per cent of critical illness claims for children.
In FTAdviser's Guide to Family Protection, Garry Webb, head of compliance for Roxburgh Financial Management, said more needed to be done to help families with specialist insurance needs for their children.
He said: "Having a plan specifically designed to cover children would be a major advancement.