These are the top tips for breaking the news that you're pregnant to your husband, partner or spouse. Lets cover the Don't's first:

Don't:
Break the news when you're driving, if you're in a really busy place, late at night when he's tired or when he's just arrived home from work.
Try to manipulate his response by saying "Isn't it great?" or "Aren't you excited?".
Be horrified by his initial response if it's a surprise pregnancy that you were not planning or expecting as he may get excited later on after he has processed the information that he's about to become a father. While he may initially be against the idea, it may just take a little while to come around to the idea later.
Finally whatever you do, don't start talking about buying the cot and the pram and how are you going to change his study where he sits on his computer and gets his private space into a nursery for your new addition immediately after you've broken the news.
In a nutshell, timing is everything and you have to give him a chance to absorb the news particularly if it's a surprise pregnancy. Moving on to the Do's.

Do:
Choose a moment when there is time for the two of you to talk. Preferably where you can go for a walk, do something that you enjoy doing together or tell him over his favourite meal you've made specially for him.
Make sure you are both calm and relaxed and in a place where you won't get interrupted. Not at the pub!
Be honest about how you are feeling as it can go a long way to allowing him to express himself as well.This is a very important point.
Do give him space to think and absorb the the idea of a new baby and becoming a dad. This gives him a chance to come around to the fabulous news.
Set ground rules about who you can and can't tell until you are 12 weeks. Everybody is different about how they decide to tell friends and family the news. For example; I can't wait to tell everybody and I find it very hard to wait until 12 weeks.
Think about how it's going to affect your relationship and once he's come around to the idea, it would be a good idea to talk about how you are going to adjust your lifestyle in order to accommodate your lovely new baby and the prospect of being parents.
Be prepared to answer all his questions ie how long have you known? when is it due? How did this happen? That is what my husband asked me each time I told him I was pregnant! My answer to that question was a very Homer Simpson "Doh!"

You know your partner, you know what their moods are like and when they are at their best. You have to think about all those things. So plan breaking the news that you catch him at the best possible moment, when he's the most receptive, the most relaxed and the most open. Good luck and happy parenting.