Half of British fathers either continue to doze or pretend to be asleep when their babies cry during the night, making many mothers resentful, a survey released on Thursday shows.

In addition to the 52 percent of dads who do not get up with their wailing children, a further 22 percent only get up after their partner has already crawled out of bed.

The lack of support leaves six in 10 mothers feeling bitter toward their partners. Restless nights also mean 86 percent of mums prefer sleep to sex.

“It’s amazing so many relationships survive the onslaught of a baby, but sadly, some never recover. And the problem is compounded because so many couples with a baby now both work and they feel ravaged with tiredness,” said Elena Dalrymple, editor of Mother & Baby magazine, which carried out the survey of 2,000 parents across the UK.

The research also showed that most babies are about five months old before they regularly sleep for seven hours a night and a third don’t sleep through the night until they are 18 months old.