1. Thou shalt have no other women before me.
For partners: Self explanatory, you would think. Yet, as our bodies become less and less sexy, it's tempting to want to look elsewhere for eye candy (or worse). Even though we, as pregnant ladies, do not find our bodies especially sexy right now, do your best to find us attractive anyway. We'll think you're crazy, yes, but also take comfort in the fact that you at least want to keep us around long enough for us to pop out the damn thing.
Anyone else: Tell us that we're glowing, or cute. (Even if we look like miserable balloons at the moment.) It's your only option. Do not say things like, "you look like you used to be pretty" (yes, a real example of a comment by a stranger) or, "better put down those donuts, you'll never fit back into your jeans at this rate."
Penalty: A sock to the jaw, at best. If you imply that we're fat while we're actually growing a live human being inside our innards, you deserve worse.
2. Do not take the pain of thy wife (or girlfriend, sister, etc...) for granted.
"Your hips are moving out of their sockets and you have a horrible case of sciatica? Eh, women have been doing this for thousands of years, it's nothing your body can't handle I'm sure." Um, yeah, women have been birthing babies for thousands of years. Men have also been working 12 hour days doing hard labor by hand in the fields for thousands of years, so they have no right to complain about how their work day went, either. It's nothing they can't handle, right?
Penalty: Take a 10 lb rock and strap it to your waist. Wrap your chest and lower abdomen so tightly that you can neither breathe nor go 5 minutes without peeing. Inject yourself with massive doses of estrogen and wear nipple clamps constantly. Take tons of iron pills until you're constipated, then take a bunch of laxatives. When sleeping, replace the rock with a live animal such as a small dog, then try to sleep through its furious kicking. Do this for 9 months. For the first 3 months, maintain a constant state of food poisoning (but don't add the rock yet). For the next 3 months, add the rock/small animal, and for the last 3 months stuff a basketball between your legs while walking and tighten the chest/bladder binds in addition to the rest. Then go 2 more weeks. (9 months? Ha!) Periodically stuff a full hand and arm up your rectum to simulate cervical exams. Then, at the end of the last horrific 2 weeks, pull the pin out of a hand grenade and swallow. (To simulate childbirth.) When you do all this, you have the right to judge how much pain we are in and how much we can/cannot handle. If you decide to abandon the experiment, apologize profusely, buy us a hot fudge sundae, make us dinner, and give us a back massage.