Well... for a start her body is about to go through some fairly major changes. You won't see much change for the first month except for one thing... She'll be floating around with a radiant pink glow of happiness while tiny little changes are taking place inside her body. One of the first things she may get is...
Aching Breasts.
One of the first changes she'll notice will be her breasts. This should kick in almost straight away. Her breasts will start aching and begin to feel heavy, so stay the heck away from them! They'll be hyper sensitive to touch so if you attempt to go there you'll be setting yourself up for a world wrestling federation style body slam. Don't risk it.
Nausea and Morning Sickness
I'll be the first to admit, there's a reason God made women the child bearers and not us Men. Women seem to 'take the pain' better than us tough guys.
Your wife will probably experience some sort of nausea at some point during the first month and for some women it may continue for months if they're unlucky. Not a nice thing at all.
I'm not sure why they call it morning sickness when they rarely feel sick 'in the morning'. So don't let the name fool you. It can hit them at any time of the day.
If you've ever suffered sea sickness, then you'll have a good idea of what it feels like (apparently).
Morning sickness resembles 'seas sickness' and not a hangover. The two are very different feelings. As some may know, a hangover is more to do with the head. Headaches, vomiting, dizziness perhaps. But morning sickness is a full body sickly feeling. I can't really explain it as well as a women who's had it, but it's something that I'm glad I don't have to go through.
So... How can you help? You can't really. Simply support her as much as possible and be there for her. Morning sickness may last a while, so do as much to help out around the house as possible. The morning sickness will be around for at least the first trimester (3 months).
The nausea will make her feel so tired and exhausted and could go on for quite a while. Even the littlest of tasks will feel like a marathon. So if your partner does the coking and arrive home to no dinner, then you need to learn to cook :-)
Fatigue
When she becomes pregnant, her body metabolism is going to increase to cope with the development of the baby. She will become very tired and need to sleep more often. Adding to this the body produces more of the hormone progesterone. Because this hormone has a sedating effect, when produced in high levels during pregnancy she will naturally feel more tired.
Dashing to the Toilet
Your partner will be making a few regular visits to the ladies room early in the pregnancy. She'll be off to the bathroom all through the night. Why? Apparenty her body produces more of a particular hormone that relaxes her intestines which helps the organs move around to make room for the baby. They must press onto the bladder I guess. If you're one of those guys who needs all the details then google it.
Cramping
This is a normal part of early pregnancy. Some newbies (first time pregnancy) may think they are having a miscarriage. If the cramping is accompanied with bleeding then see your doctor just in case. Again... google it if you need details.
Constipation & Wind
Yes guys... your lady does fart (and so does the Queen of England). Remember earlier I mentioned the increase in hormones? This is the side effect. The odd 'toot toot' now and again. This can be a little embarrassing for your lady. Especially as they like us to believe they don't actually do those types of things.
Craving
Anyone for some pickled onions?
My wife didn't really go through the craving stage. She's had an insatiable craving for chocolate for years. So nothing abnormal there.
However, she did experience a metallic taste in her mouth for a short while. This is apparently also to do with the increased hormone flooding her body.
Just as my wife did, many women hate the smell and taste of meat during pregnancy. Just the smell of it would make her gag and almost puke.
That's the main stuff I can think of, so I hope it helps you guys in some way to understand what to expect when she's expecting. All women a different, so you never know what to expect when she's expecting.