When eating out, always ask about the ingredients in a sushi roll, and make sure to specify that you can’t eat any raw fish.

If you went right from seeing two positive lines to reading about what you have to give up now that you’re pregnant, you’re not alone. While some of the things to avoid are pretty obvious, there are food items you may think are healthy but can actually pose a safety risk to you and your baby.

One item to add to your list of no-no’s is that tasty spicy tuna roll. That’s right, along with drinking your favorite glass of wine, eating turkey sandwiches, taking prolonged dips in the hot tub, and scooping kitty litter — yes, you can delegate this to someone else! — eating sushi, at least the kind with raw fish, isn’t something you’ll want to do until after giving birth.

That said, before you cancel dinner reservations or toss out those delicious and healthy California rolls, there’s some good news — not all sushi is off-limits.

Related: 11 things not to do while pregnant

Any sushi with raw or undercooked seafood is off-limits, according to FoodSafety.gov. Eating raw or undercooked fish can expose your growing baby to mercury, bacteria, and other harmful parasites.

“Due to immune system changes during pregnancy, pregnant women are more susceptible to infection, which can increase the risk of miscarriage, stillbirth, uterine infection, and preterm delivery,” says Kristian Morey, RD, LDN, clinical dietician at The Center for Endocrinology at Mercy Medical Center.

What’s more, your baby is especially vulnerable to mercury exposure, which Morey says can result in neurological issues, as methylmercury has toxic effects on the nervous system during development.

Short answer: Right away! In fact, even if you’re in the process of trying to get pregnant, it’s a good idea to stop eating raw fish. The no-undercooked-or-raw-fish-sushi rule applies to all three trimesters.

During the first trimester, several significant developments are happening, so it’s crucial to abstain as soon as you know you’re pregnant. During weeks 1 to 8, the brain and spinal cord begin to form. This is also the time that the tissues that form the heart begin to beat and the eyes, ears, and nose develop.

All of your baby’s major organs will develop and function by the end of the first trimester. It’s during these first 12 weeks that the fetus is most vulnerable and susceptible to damage and harm from exposure to toxic substances.

“During pregnancy, your immune system is lowered since you’re sharing it with a growing fetus,” says Dara Godfrey, MS, RD, registered dietician for Reproductive Medicine Associates of New York. When you have a weakened immune system, Godfrey says you’re more susceptible to bacteria or parasites that could be present in raw or improperly handled fish.

However, if you just found out you’re pregnant and you’ve been indulging in raw or undercooked sushi, take a deep breath. It’s going to be OK. To help ease any concerns, let your doctor know that you’ve had sushi with raw fish. They’ll be able to answer any questions you may have and guide you on safer food choices during pregnancy.

Now that you know sushi rolls with raw fish or raw meat are a definite no during pregnancy, you might wonder why one of your favorite meals didn’t make the cut.

“Undercooked or raw fish increases the risks of exposure to certain types of bacteria during pregnancy and is more likely to contain bacteria and parasites,” says Dr. Lisa Valle, DO, OB-GYN at Providence Saint John’s Health Center.

Listeria, a bacteria that causes listeriosis, is a type of food poisoning that can pose a serious health risk for you and your baby. And pregnant women are at a higher risk of getting listeriosis.

In addition to vomiting and diarrhea, it can cause preterm labor, stillbirth, and miscarriage. Additionally, if a baby is born with listeriosis, there can be problems with their kidneys and heart, as well as infections of the blood or brain.

To help prevent listeriosis, the American College of Obstetricians and Gynecologists (ACOG) recommends that pregnant women avoid eating sushi made with raw fish, among other foods like hot dogs, lunch meats, and unpasteurized milk.

Furthermore, raw fish can result in increased mercury exposure to your baby. When a pregnant woman is exposed to high levels of mercury, which is a metal, the health of the baby and mom are threatened. “High levels of mercury can cause brain damage, hearing, and vision problems in the baby,” says Valle.

Godfrey says even if you’re getting good quality fish from a reputable restaurant that employs qualified chefs using proper handling techniques, they can’t guarantee that their raw fish is safe to eat.

In a nutshell, there are mainly two reasons why you shouldn’t eat raw fish sushi while pregnant:

  • bacteria and parasites to which you have lowered immunity (may be found in all raw fish, meat, and milk products)
  • high mercury levels (found in many types of fish — more about this below)

Related: Is it safe to eat sushi while breastfeeding?

Remember when we said there’s good news? Well, here it goes: You can eat some sushi rolls while pregnant. “Sushi that is cooked (with seafood) in addition to vegetable rolls are safe for pregnant women to consume,” says Valle.

In fact, the current guidelines from the ACOG recommend that pregnant women eat at least two servings of low-mercury fish, such as salmon, catfish, and other fatty fish and shellfish that contain omega-3 fatty acids, per week.

But before you reach for that salmon roll, make sure it’s cooked, as you need to protect yourself and your baby from both mercury and listeria.

Cooked rolls, if heated to a temperature of 145°F, are OK to eat during pregnancy if made with low-mercury fish.

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When choosing a roll with cooked seafood, the Food and Drug Administration (FDA) tells pregnant women to avoid these high-mercury fish:

  • swordfish
  • tilefish
  • king mackerel
  • marlin
  • orange roughy
  • shark
  • bigeye tuna

“Fish high in mercury tends to have mercury levels of more than 0.3 parts per million,” says Valle.

However, a California roll, which is one of the more popular sushi rolls, is often made with imitation crab meat. Since this type of crab meat is cooked and made from lower-mercury fish, it’s generally considered safe for a pregnant woman to eat.

When it comes to any sushi roll with seafood, make sure to ask about the ingredients. You may think you’re just getting crab meat or shrimp, but there could be other types of fish in there that are high in mercury.

Some commonly cooked rolls you may see on a menu include:

  • California roll
  • ebi roll (shrimp)
  • unagi roll (cooked eel)
  • spicy chicken sushi roll
  • spicy crab roll
  • spicy shrimp roll
  • chicken katsu roll

Some common vegan rolls you may see on a menu include:

  • cucumber maki roll
  • cucumber avocado roll
  • shiitake mushroom roll
  • Futomaki roll (when vegan)

Pregnancy is a time to pay extra attention to what you put in your body. Knowing the ingredients in the foods you eat can help keep you and your growing baby safe.

If you’re unsure about what you should and shouldn’t be eating over the next 9 months, talk with your doctor or a registered dietician. They can help you create a diet that is both safe and satisfying.