Sure, it's the most beautiful life-affirming experience in the world but with a passion-killing combination of sleepless nights, no time alone, endless decisions to be made and a third – highly demanding – person thrown into the dynamic, even the most solid relationship can be shaken to the core.
From competitive tiredness to who knows best, here are some of the most common relationship flashpoints for new parents. Do any of these sound familiar?
The tired Olympics
"My husband and I used to waste precious sleep time arguing about who was the most tired. Sometimes he'd say he'd been awake all night but I knew he hadn't because I'd heard him snoring. Other times I'd exaggerate how many times I'd been up in the night with the baby. We'd even argue about who'd had the best quality of sleep.
"It was all about point-scoring – because if you were the most tired, you got the best privileges, like the next lie-in or not having to be the next one to get up.
"Looking back we should have been kinder to each other. I still think I was more tired than him though!" Andrea, Slough
Who knows best
"I felt like I had no idea what I was doing when I first had my daughter. I now realise most new mums feel like this but at the time I just thought I was a complete failure. This made me really defensive. Every time my boyfriend questioned anything I did or made suggestions, I'd fly off the handle and think he was undermining me.
"I was constantly saying, 'Oh, so you're saying I'm a bad mum?' He'd reply, 'No, I'm just asking you if you packed the nappies' or 'I just wondered if we should try swaddling him'. The worst part was he was often right.
"I took every comment as a dig at my parenting skills – or lack thereof – even though he was just trying to help." Maddie, Nottingham
Competitive stress levels
"I have a pretty stressful job in the city – long hours, high-pressured presentations to clients, multi-million pound deals and a tyrannical boss. When I first went back to work after paternity leave I found it a real struggle and felt hard done by when my girlfriend asked me to help out with night duty from time to time.
"All I could see was that while I was in stressful meetings, she was at mother & baby groups, eating cake with her NCT pals or messing about on Facebook.
"Then one day, when she was struck down with a sick bug, I had to walk a mile in her shoes. Or should I say walk about eight miles to get our son to stop crying and go to sleep. I realised there is no more demanding boss than a newborn baby. I think we had a better understanding after that - and I have full respect for anyone who spends all day looking after their kids." Richard, Bournemouth
Whose turn it is
"Parenthood seems to have turned me and my husband into a pair of big kids. This would be a typical conversation these days:
Me: 'But I changed his nappy last time!'
Him: 'But I did the explosive one in Starbucks.'
Me: 'But I change them all day long and have had loads of explosive ones.'
This can go on for several minutes at a time. Luckily we can laugh about it though. We say things like, 'Aw, I think she wants daddy' or 'Mummy's very lazy today, isn't she?' to wind each other up. It stops us from taking it all too seriously." Jane, Huddersfield
The disappearing act
"My husband is like the invisible man when the baby needs his nappy changing or it's feeding time or nap time. He'll mutter something about going to look something up on the computer or filling the car up with oil and then reappear an hour later – usually when the baby is changed, fed or asleep.
"To be fair he does do a lot of jobs around the house. But he forgets that I'm doing baby stuff all day every day. To me, sorting out the washing or nipping out to the shop is a break.
"He's got a lot better since I confronted him about it. And now that I work part-time from home I can get my own back with sudden, urgent deadlines!" Christine, Blackburn
Good cop, bad cop
"Like all toddlers, our little monster can be quite a challenge. When we're both tired and stressed with work and he's playing up it can be hard to stay cool, calm and collected. Occasionally one of us will snap and get cross.
As soon as it happens, the other one always jumps straight in and gets all protective and holier than thou: 'Don't talk to him like that'/'It's not his fault you've had a bad day'/'He's only a baby'.
Yet we're both guilty of doing it – and we both feel terrible immediately. I guess it's easy to be the 'better parent' when you're the one quietly observing" Gemma, Stockport
What do you and your partner bicker about? Tell us in the comments box below.