I am not aware of any specific mattress designed exclusively for pregnant women that offers adjustable springs or supports to accommodate different firmness preferences for couples. However, mattress technology and product offerings are constantly evolving, so it is possible that new options have been introduced since then.
To find the most up-to-date information on mattresses designed for pregnant women with adjustable features, I recommend conducting an online search or reaching out to mattress manufacturers or retailers. They would have the most recent information on any products specifically tailored to the needs of pregnant women.