The survey, carried out by Swedish motherhood magazine "mama", also revealed that 48 percent of Swedish mums manage to have sex one to two times per week, while 4 percent claimed they manage to get it on with their partners on a daily basis.
However most mothers in Sweden, 51 percent, reported having sex only once or twice a month, while 7 percent said they only had sex once or twice a year.
Despite the modest frequency with which most Swedish mothers have sex, mama's 2012 sex survey also found that motherhood doesn't necessarily diminish Swedish women's sex drive.
Two-thirds of mothers said they desired to have sex once or twice a week, while 10 percent dreamed of doing the dirty on a daily basis.
But the demands of everyday life often stand in the way of Swedish mothers fulfilling their sex dreams, according to the survey.
"I would like to take the initiative more often, but I'm often too tired and I don't have the energy to start anything. The sex drive is there, so if my partner initiates sex, I'm game," one 34-year-old mother of three told the magazine.
In terms of when and where Swedish mothers have sex, the survey found that an overwhelming majority – 90 and 92 percent respectively – have sex at night and in the bedroom.
Swedish mothers also reported that the struggle to balance work and family life left little time for long lovemaking sessions, with only one percent having sex sessions lasting an hour or more, while 15 percent said that they spent between 30 minutes and an hour at a time between the sheets
But most mothers in Sweden, 65 percent, said that their lovemaking sessions usually last between 15 and 30 minutes.
One in four Swedish mums reported fantasizing about being unfaithful, while 10 percent reported they had actually cheated on their partner.
The most common partners featured in Swedish mothers' fantasies are ex-boyfriends, followed by co-workers.
Swedish mothers also offered a number of ideas for how they'd like to spice up their sex lives, including making sex less routine.
"New positions and not just quickies. And in more exciting places like outside," said a 32-year-old mother of two.
"More spice in the form of a sex toy now and again," said a 36-year-old mother of one.
The survey is based on responses from 663 mothers, 92 percent of who are married or live with their partners, and who participate in mama's reader panel.