The arrival of a baby is greeted with joy and delight by family and friends alike.
For the little one's parents, however, nothing will ever be the same again - especially their love life.
They can suffer a phenomenon labelled 'baby quake', which shakes up their relationship and often makes them shun intimacy.
Experts warn that new parents may stop having sex, which can taint their marriage and ultimately drive them apart.
Their study found almost two-thirds of new parents have a concern about their relationship which did not exist before.
Often parents are so worried about their new roles, either staying at home or being the main breadwinner, that they neglect each other and stop regarding themselves as romantic partners.
Relationship charity OnePlusOne, which carried out the study in the UK, said 40 per cent of new mothers who expressed worries feared they were no longer sexually attractive to their partners.
At the same time, more than a quarter of new fathers were worried their partner had stopped wanting to make love.
Just over a quarter of couples longed for some time alone instead of constantly worrying about their baby. Charity director Penny Mansfield said: 'Becoming a parent can put a relationship under extreme pressure as each partner tries to adjust to their new role.
'For some, it can be almost like a mini-earthquake. Often one becomes a stay-at-home parent and this can be very isolating. If they feel the partner out at work does not appreciate them, it can lead to arguments.
'Time alone is vital because it's very easy to slip into seeing each other as parents rather than as romantic partners, leading to issues around sex and intimacy.'
The study of more than 1,400 mothers and fathers also showed that nearly a quarter have split up from the partner with whom they had their first child.
Of those parents who had separated, two-fifths parted company during the pregnancy or before the child reached three years old.
The charity said some of the challenges couples face included day-to-day gripes such as how to divide up the cooking and cleaning as well as bigger issues such as clinging to a sense of identity.
- Daily Mail