The answers may lie in our complicated socio/cultural influences. Chocolate cravings, particularly among women, may result from a combination of factors such as, a reaction to stress, hormonal fluctuations and modulations of certain neuropeptide concentrations but also from our relationship with food. For example, studies from countries, like Spain, where chocolate consumption viewed as a part of a healthy diet and is generally higher, report very limited cravings for chocolate. This is contrasted by American women, who’s chocolate consumption is more restricted or considered a "treat". American women report the strongest craving for this rich delicious treat.
In North American culture, chocolate, and carbs in general are often turned to in order to treat and soothe our emotional selves. It is possible that when pregnant, especially in the first trimester, when we might feel nauseous, bloated, tired and crabby (because of hormones), we turn to foods that are easy to digest (make us less nauseous and require less energy to process), increase our comfort levels and boost our feel good serotonin levels.
Chocolate is also rich in magnesium. Pregnancy, the first trimester in particular, is a time when the body's demand for magnesium is elevated. Perhaps you're body is telling you it needs some magnesium? Satisfy the urge with some high quality 80%+ dark chocolate or mix raw cacao with some psyllium husk (great for constipation) and water or nut milk. When you make this cacao "paste/pudding" and eat it with a spoon (I like some cacao nibs on top), it will eliminate your cravings and give you a solid dose of magnesium, potassium and a shot of iron. Other foods rich in magnesium include: dark leafy greens (spinach in particular), cashews, almonds and sesame seeds (eg tahini).
Carb cravings in particular, in the first trimester may also be a result of a few different things going on inside your body.
First, a more relaxed attitude surrounding food when pregnant. Women who were previously restricting carbs, a common practice in the Paleo/Keto community, may see pregnancy as a ‘hall pass’ to enjoy carbs in all forms and as a result may experience intense cravings for these starchy and/or sweet delights. I say, go for it, just remember to take your vitamins and don’t go ‘hog wild’ on sugar. Whole grain gluten free toast, pastas, rice, quinoa, sweet / white potato, squashes and cereals are your best bet.
Secondly, when nausea hits sometimes all your body can tolerate are carbs. They are easily digested, bland and palatable to most women who feel nauseated. If this is all you can get in, go for it. As I’m writing this, I myself am pregnant in my first trimester, nauseated AF and I’ve eaten nothing but gf toast/ bagels, muffins and pasta over the past 48 hrs. I don’t feel bad about it one bit.
While we are on the topic of carbs, I think it’s also important to recognize the biological aspects of carb cravings, aside from chocolate, in pregnancy. Your body needs carbs when you’re nourishing your fertile and pregnant self. Carbs are required for proper hormone function and once you become pregnant, your body becomes increasingly more insulin resistant as a way of increasing fuel availability to your growing baby. This insulin resistance can cause carb cravings particularly in the first trimester. More on Carbs can be found on my previous post, "How Many Carbs Should I Eat When Pregnant?"