The tragedy comes just two years after the couple lost their three-week-old son Mason Martin to SIDS.
The couple are believed to have recently started trying for another child.
“She is a girl who has really had it tough and it just breaks our hearts to see her have to go through this again,” Ms Mason’s stepfather, Graham Hood, tells The West.
“They had both been a mess since (Mason’s death) and ... with this now coming on top of that, it is beyond the pale.
It is just lucky that she found the strength to get away (from her attacker).
“There were three or four times that she said she felt herself slipping away, but she managed to find the strength within herself to fight back.”
Ms Mason’s family have set up a GoFundMe page to raise money for medical costs and to help get her get back on her feet.