A detailed study into the trials and tribulations of becoming a parent found that as well as days full of love and wonder, many mums find the initial 12 months emotionally and physically draining.
And mums admit the more negative aspects of parenthood – such as the sleepless nights, the feeling of being lost, loneliness and bewilderment – outweigh the positive for 54 per cent of the time.
The report finds that it is only when baby reaches the age of 11 months that the happier elements of motherhood come to the fore.
At this point, new mums finally start to feel that they know what they are doing and are more confident in their role.
Leading GP Dr Pixie McKenna says "It is easy to under estimate the impact having a baby has on a woman's life.
"Before embarking on parenthood, many women are settled in a job, know what they are doing on a day-to-day basis, and are confident in the role they have carved out for themselves.
"They have independence, aren't responsible for anyone but themselves, and their abilities and decisions aren't questioned constantly.
"The minute a baby comes along, a woman's world is turned upside down – with that initial rush of love and joy comes the unknown, and it is this which can throw women completely off balance."
The study of 2,000 mums by Nurofen for Children found more than half of new mums suffered a major knock in confidence in the first year, feeling they have no idea what they are doing.
Many mums would have liked to have a manual, more help, or instructions on how to cope with certain aspects of motherhood.
Half of those polled wish someone could have told them why the baby was crying, and 43 per cent would have liked tips on how to deal with sleepless nights.
Researchers found 89 per cent of women's lives completely change by having a baby, with their relationships at home and work life taking the biggest hit.
Even relationships with friends and family can be affected by the introduction of a new-born, while just under half of those polled had to put a stop to old hobbies and interests.
And while mums said they did start to really enjoy motherhood from about six months in, 65 per cent admit they find the first year incredibly stressful – 52 per cent genuinely feeling as though they'd lost their identity.
Two-thirds of those polled found it difficult to cope with the sleep deprivation.
Four in 10 women had no idea how to get their baby to sleep in a regular pattern, while 35 per cent felt they were making it up when it came to feeding the child.
Getting the baby settled into a routine, juggling the cleaning and cooking with childcare, and coping with the sheer responsibility are all aspects women would have liked training on.
A quarter of mums didn't have a clue when their baby was supposed to be reaching different milestones with regards to their learning and development.
When asked what they missed most about their lives pre-motherhood, 55 per cent said social life, 35 per cent said work, and 51 per cent wished they could have their old body back.
The top things mums wish they had known in the first few years of motherhood:
1. Why the baby was crying
2. How to cope with sleepless nights
3. The sheer responsibility of being a parent
4. Whether to let them cry it out or not
5. How to get a baby settled into a routine
6. How to recognise when a baby was ill and not just grumpy
7. How to juggle the house-cleaning with looking after the baby
8. Whether you should be querying things with a doctor/health visitor
9. Knowing that mums in the same position may only be appearing to cope
10. How to cook a meal while looking after a baby