Newline in parameteres

$data = $this->EE->TMPL->fetch_param('data_containing_newline');

Does fetch_param() strip newline from input? If so, is there a way around it?

This is what I’m trying to do:

{exp:freeform:entries limit="1"}

{exp:mailchimp_ee:subscribe interest_groups="{newsletter_preferences}"}

{/exp:freeform:entries}

{newsletter_preferences} contains entries delimited by newline (these show in the template), but if I use in in the way described above, when fetching param with fetch_param() newline is gone :(

Help - please? 😊