Pregnancies seem to be going around here at Epicurious — I've joined my colleague Siobhan in the club. Being someone who loves food, and also a typical thorough editor type, before I got pregnant, I read up on which foods I was supposed to be eating and not eating.
Much to my surprise, it was incredibly difficult to get accurate and thorough information on which foods to avoid. For instance, most pregnancy books and web sites say to avoid soft cheeses made from unpasteurized milk. “But wait a minute,” you're probably thinking, “aren't those illegal in the United States?” That's exactly right: It's against U.S. law to sell any raw-milk cheeses that haven't been aged for at least 60 days, which rules out any soft varieties. This is why cheese aficionados go to great lengths to sneak things like luscious raw-milk Camembert into the country. (My parents have a great story about trying to hide a pungent wheel in an overheated overhead compartment on a flight from Normandy, but that's a tale for another day.) But it certainly means that your average pregnant American is not likely to accidentally ingest a soft raw-milk cheese. If you want to eat one in America, you really have to seek it out.
My doctor was not a whole lot more helpful — she just gave me the same info as the books. It seems like there's a real knowledge gap here — most doctors are not food experts, and most foodies don't know the details on pathogens and illnesses. So I was pretty much on my own.
After a lot of research, I finally made my own decisions based on what I could find out. The results of my research are below — I hope they'll be helpful to other people in my situation. Of course, I'm most certainly not an expert, and some of this comes down to personal comfort with degrees of risk. So I'm definitely not telling anyone what to do. But if you're looking for more information to help you with your decisions, here's what I was able to turn up:
The main risk here is listeria. Listeria is a bacteria that can be found in milk and other foods. (See below for the others.) It's quite rare in the United States, but when you're pregnant, your immune system undergoes changes that makes it harder for it to fight off infections, which means that, if you did ingest listeria, you'd be more vulnerable to it. If you did get infected, it would likely cause miscarriage or stillbirth.
So, this is a serious issue. The question, then, is how likely are cheeses to contain listeria? It's killed by pasteurization, so with non-raw-milk cheeses, the only danger would be if the milk were recontaminated after it was pasteurized. According to my research, this is not very likely. However, if the milk were recontaminated, a soft cheese, particularly one with a rind like a brie, would be a good medium for the bacteria to grow.
So, this is an iffy one. Bottom line: soft, raw-milk cheeses are risky. Soft, non-raw-milk cheeses are much less so, though there is a very small risk, particularly if the cheese has a rind. Feta, because it's stored in a brine that inhibits bacterial growth, is a bit safer, as long as it's pasteurized. Hard cheeses, even those made from raw milk, are always safe because they're aged for at least 60 days, a period which would kill any bacteria present. Mozzarella, cottage cheese, ricotta, and cream cheese (and mascarpone, etc.) are also always safe. All cheeses are safe if they're heated through until steaming, because heat kills listeria.
There are two dangers with fish: listeria and parasites. They're both killed by cooking. Listeria lives only on the surface of the flesh, while parasites can be in the interior. Listeria is even more rare on fish than it is in milk, but, as I mentioned above, if it were present, it would be quite dangerous. Parasites such as worms are fairly common in fish, especially salmon. However, most sushi-quality fish is frozen for a period of time, which kills parasites (though not listeria). Parasites are not as dangerous during pregnancy as listeria, but they can occasionally cause complications.
What this means is: Sushi is slightly risky. Partially-cooked fish, such as salmon cooked medium-rare, is also slightly risky, though not very. So, this is a personal choice. My decision has been to avoid sushi and eat undercooked fish only at very high-end restaurants, where I'm confident in its quality, or when I've bought it myself and know it's sushi-quality.
Smoked fish also has a slight risk of listeria, though not of parasites (which are killed by the smoking process). In the U.S., pregnant women are told to avoid smoked fish, but in the U.K., they're told it's fine. If you're concerned about the risk, heating the fish through until it's steaming will eliminate any bacteria. (I actually tried this with smoked salmon, and it resulted in a very tasty product similar to hot-smoked salmon, which was delicious with potato pancakes.) Pickled fish such as pickled herring is safe, because the pickling brine is not hospitable to bacteria. Other cured fish such as gravlax are a bit risky, the same as raw fish.
Another seafood product that's a pregnancy concern is caviar. The risk here is listeria, unless the caviar is pasteurized. I had a hard time finding out exactly which brands are pasteurized, but it seems that Romanoff offers a pasteurized product. If the caviar is not clearly marked pasteurized, though, it's definitely a risk.
In addition, raw shellfish such as oysters and clams can be contaminated with salmonella, which is not as dangerous to a pregnancy as listeria, but would make you very sick, which could cause complications. Salmonella is not exactly common in shellfish, but it's not altogether uncommon either, particular if the product is from polluted waters. So, this is a bit of a risk.
And finally, while many types of seafood contain beneficial Omega-3 fatty acids, which are recommended for pregnant women, some varieties are also loaded with mercury, which can harm the development of the baby. This article from the American Pregnancy Association has a good list of which types have the most mercury.
The biggest risk in meat products is listeria but, as above, the risk is only with uncooked meats, and it's not that common. Products such as pâtés are the riskiest. Sliced deli meats are in the same category as smoked fish — avoided in the U.S., but not in the U.K. If heated until steaming, they're definitely safe. Dry-type salamis are safer because the low-moisture environment is not friendly to bacteria. Hot dogs cause cases of listeriosis in the U.S. each year, so you should be sure that they're cooked all the way through.
Another risk with raw meat is toxoplasmosis. This is a parasite that can be in the flesh. It's killed by freezing or cooking, but only if the meat is cooked all the way through. Toxoplasmosis can cause problems during pregnancy ranging from stillbirth to birth defects. However, it's pretty rare in meat in the U.S. To be completely safe, you'd need to cook all meat until well-done.
Other contaminants such as E. coli and salmonella are more common on U.S. meat, as we've all seen from recent food recalls. Like salmonella, E. coli is not as dangerous to a pregnancy as listeria, but can cause complications. However, like all bacteria, these are only present on the surface of the meat, not in the flesh. The biggest danger is ground meat, because bacteria from the surface can be distributed throughout the entire product. Therefore, to kill any bacteria, products such as hamburgers need to be cooked all the way through. A solid piece of meat such as a steak would only need to be seared to kill bacteria.
The risk here is salmonella. This bacteria is not uncommon on eggs in the U.S., and, as I mentioned above, is moderately dangerous during pregnancy. To kill it, eggs need to be cooked all the way through. Recipes made with undercooked eggs, such as buttercream icing, hollandaise sauce, mousse, and homemade mayonnaise, can also contain salmonella. However, commercial versions of these products use pasteurized eggs, so they're not a risk. My personal choice has been to eat undercooked eggs only if they're from free-range chickens from a local farm, which have a lower risk of salmonella than those from factory farms.
Veggies and fruits can be contaminated with salmonella or E. coli, so it's best to wash them thoroughly. Some experts advise avoiding sprouts, which are hard to clean thoroughly. Again, my strategy is to go for local produce whenever possible, to avoid contaminants present in the factory food system. And of course, all bacteria are killed by cooking.