Bright Grey and Scottish Provident sales have declined by almost a fifth over the first three-quarters of the year.
The pair or protection providers, who are both part of the Royal London group, posted a joint fall of 19% in new business during the nine months to the end of September.
Previously the businesses had been reported individually, but over this time period they show combined present value of new business premiums (PVNBP) of £251m, down from £310m at the same point in 2009.
The results maintain a trend set earlier in the year and illustrate the present difficulties of the protection market.
Royal London put the decrease down to the still slow mortgage market and suggested that market consolidation demonstrated that other insurers were also suffering.
"The recent contraction in the number of providers is a clear indication of how difficult and competitive the market is," it said.
However, it added that one area of success was it business protection range and the pair were confident of seeing growth as the mortgage market improved.
The group's bancassurance protection distribution sector, although also affected by lower levels of mortgage-related business, has seen an increase of a 21% in the third quarter compared to last year, something it put down to the introduction of two new products.
Overall, total new life and pensions business at Royal London increased 26% to £2.32bn (on a PVNBP basis).
