One time I was pregnant. There were some simple things that I really wanted from my partner but at the time, I was too emotional to ask for them in a constructive way. Being a parent is a radical experience, and the starting point is the pregnant part. If you can provide an environment that is comfortable to your pregnant partner, the pregnancy, the birth, and the first months of insanity can be greatly improved. I believe that a pregnant woman's needs are totally within the scope of what you can do.
Step 1: Take Notice of the Amazing Power of Her Body
Most everyone wants their work to be appreciated, especially in relationships. When someone is working hard, it makes the experience more enjoyable to know that it is not in vain. Your lady is creating a human being without even knowing what she is doing. The baby is being made from parts of her body. It's totally insane and powerful, and if just once a day, you let her know that her body is amazing and doing a good job, you will make her happier.
Step 2: Water and Vitamins
Pregnant women are thirsty. They need beverages wherever they go. It would be really really sweet if you could make sure that she has water. She might already be on top of this water-having need, but I guarantee you that she will forget her water bottle at least one time. If you are the one that produces a little bottle of water for her from your bag or car or whatever, you will earn yourself some hugs and you will avoid the panic and crazed behavior that happens sometimes when a pregnant woman gets thirsty and can't find water. I think it's totally an animal thing, but never go walking with a pregnant woman unless one of you is carrying water.
Vitamins. Likely, she will take some kind of supplemental vitamin while pregnant. If you can make sure that she takes her vitamins every day with maybe even just an email or text message, she will feel like she is part of a well-oiled pregnancy team.
Step 3: Reading Material
She will want you to read a book that you probably don't want to read or don't have time to read. It might be a child rearing book or a birth book. If you really can't bring yourself to read it, find a birth book or a pregnancy/child book of your own and read it. Even if what you choose is very short, it will be the effort that she remembers. If you can make it through Spiritual Midwifery, you'll win an award. Otherwise, just read The Nursing Mother's Companion. Read the first 50 pages. She will forget all about all the other things she wants you to read.
If it were my choice, my man would've read The Continuum Concept. In fact, I wish everyone in the whole world would read it.
Step 4: Offer to Go With Her
Whenever she has an appointment with the midwife or ob/gyn, offer to go. Even if you know that she will say no, offer. Don't wait until she asks you. The more that she feels a part of a team, the more comfortable she will be with the idea of bringing the baby into the world.
Step 5: Help Her to Prepare
Mentally: She needs to know in her heart that she can birth this baby. Her body already knows everything about having the baby, but especially if it is her first time, there is a lot of uncertainty about what the process will be like. As long as at her core, she trusts her body and knows that she can do it, she will be as mentally ready as she can be.
Nesting: If she wants to rearrange everything, you have to help her, or hire someone to help her. She's pregnant and by the time the nesting urge hits and she has to fold and re-organize every thing in every cabinet, she will be quite large and could benefit from an extra pair of hands.
Birth Plan: Talk to her about her ideal birth, whether hospital, at home, birth center, in the lake, whatever. Find out what her fears are and try to address them. As she gets closer to the due window, make sure that all the supplies for birth are in order.
Step 6: Be Patient
She may be acting a little funny. She's got all these new levels of hormones going on and likely doesn't realize it most of the time. She is still the same lovely lady that she always was. What she needs is for you to just accept how she is and to not get angry with her. It will calm down eventually and you can both look back and laugh at the time she had a crying fit outside that Mexican restaurant because she had forgotten to take her vitamins.
Make sure you give her a big chocolate bar the day after the delivery. She will need the calories and it will make her the happiest she's been since the baby came out.
Step 7: Bonus Material
If you're a real go-getter, you can always do more for the mom and baby. Here are extra things that you can do if you have mastered everything else:
Food: She is hungry and she has to pee. But the hunger part, you can help out with. Near the end, especially, she will be heavy and her feet will tire of standing, but she will be at her hungriest part of the pregnancy. If you can make a good meal for her every day, you will be doing her a great favor. You will keep her from eating a whole box of golden grahams for dinner instead of making something for herself. Lean protein and veggies and complex carbohydrates! Not too much salt! If she needs it, she'll add it. She needs Iron and Calcium, especially, so make her something with Kale or Collard Greens or something. A good solid kidney bean never hurt a pregnant lady, either.
Feet: Even if your lady is at 35 weeks and buzzing around the world like she's not pregnant, her feet hurt. And even if she says they don't hurt, a foot rub will be well received and will help you bond with her new body and give you some quality time together that you might not get for months or even years following the birth.
Birth: Near the end, she will know that the baby has to come out soon. Maybe she will have already passed the 'due date'. The tension and anticipation of the baby's arrival and the mystery of the labor process is no good for her. Ease that tension as much as you can through talking to her about the baby and birth. And the most important part: get intimate. If you're having a hospital birth, you might not be able to make-out and get really into it at the hospital, so help her with her hormones at home, whenever you get a chance. Show her that you love her body! The hormones that put the baby in there will get the baby out.