There are so many things that pregnant people are forbidden from doing, and there are so many warnings about the harm that usually-harmless things will do to you or your baby. It's important to wear your critical-thinking cap all the time, but I think especially when you're pregnant. Most websites and other pregnancy resources will err significantly on the side of caution, giving the impression that even a bite of ham will give you listeria, and a even a sip of coffee or alcohol will cause a miscarriage or fetal alcohol syndrome. These generalizations protect the websites from being sued, but they also create a cloud of uncertainty and fear for pregnant people. Always, always, always ask your doctor or midwife about these types of things. They will (hopefully) be aware of the current research and can give you more information about what things are safe to eat, drink and do while you're pregnant.
Pregnant people are told to avoid deli meat because there's chance it carries listeria. Listeria is a bacteria that is present when foods are prepared incorrectly or contaminated at processing plants. Cooking things hot will completely kill listeria, but not fully heating contaminated foods or eating contaminated foods cold will infect you. Pregnant people are at more of a risk for contracting listeria because their immune systems are suppressed.
Listeria infection is VERY RARE. According to the CDC, 1600 people in the US contract listeria in a year. That means you have a 0.00000477% chance of getting listeria in a year. In 2024 (so far), there were listeria outbreaks in deli meat, frozen meals and pre-prepared salads, which means you have even less of a chance if you're heating frozen foods correctly and not eating cold prepared salads from the grocery store!
Talk to your doctor about the risks and benefits. Deli meat is an easy source of delicious protein - an important nutrition building block in anyone's diet, but especially in pregnancy. If you take reasonable precautions (buy your deli meat from a reputable source; keep an eye on listeria outbreaks) the risk to you is quite small.
If you decide the risk of listeria outweighs any enjoyment you might get from eating deli meat, that's also fine! Pregnancy (and life!) is just a matter of weighing those risks and deciding which ones you want to take.
It's a pretty well-established recommendation that pregnant people can drink 200-300mg of caffeine a day with no ill effects (that's about 1 to 1.5 cups of full-caff coffee). Some ill effects that are cited when consumption is beyond that limit are increased miscarriage risk and low birth weight. Again, it's up to you to weigh these risks vs rewards. One study I found estimated that babies born to caffeine drinkers (who drank any amount of caffeine) were 3 ounces smaller than babies born to caffeine non-drinkers (1). In my opinion, three ounces is not that much of a difference, and sometimes I need a cup of coffee to keep the demons at bay. The reward, in my opinion for myself, outweighs the risk.
There are many studies and resources on alcohol consumption during pregnancy. A sip of wine or beer or a cocktail is not going to hurt you or the baby. There's simply not enough alcohol in a sip to do anything to anyone. If you have more than just a sip, that's where things start to get murky. The main thing every resource will tell you is that "there is no known safe quantity of alcohol during pregnancy." And since it would be unethical to do a real study, this subject mostly relies on anecdotal evidence.
If you were comfortable sleeping on your stomach, it's completely fine. When it's too sensitive or there's too much pressure to get comfortable on your stomach, stop sleeping on your stomach.
NIH Study - https://www.nih.gov/news-events/news-releases/moderate-daily-caffeine-intake-during-pregnancy-may-lead-smaller-birth-size