Of all the times in your life to pay attention to what you put in your mouth, pregnancy ranks as number one. That’s because mom’s nutrition during those nine months can have a huge impact on the baby she’s nourishing. “But you definitely shouldn’t think of it as ‘eating for two,’” warns nutritionist Tara Gidus, RD, author of Pregnancy Cooking & Nutrition for Dummies (Wiley 2012). “Eating too much will just result in unnecessary weight gain.” In your second and third trimesters you do need a few more calories, but only about 300 to 400 a day. So the key is to focus on food quality, not quantity. Here, what you need and what you need to skip:

Eat this:

  • Leafy greens: These are a rich source of vital folate (essential for baby’s spinal cord development).
  • Meat, poultry and fish: Not only are these foods a great source of protein, but also of iron. Because your blood volume increases during pregnancy, your iron needs increase too.
  • Milk, cheese, yogurt: Dairy products will help you get the calcium you need in order to keep your own bones strong and help build your baby’s too.
  • Salmon: This fish is high in Omega-3 fatty acids (good for baby’s brain development, plus helps mom avoid complications like pre-eclampsia and high blood pressure) and low in mercury.
  • Egg yolks: If you insist on egg-white omelets you’ll miss out on a nutrient called choline that’s found in the yolks. And choline helps with your baby’s neural tube and brain development.
  • Prenatal vitamins: Step up from a basic multivitamin to one of these specially formulated supplements to ensure that you’re getting adequate amounts of all the essential pregnancy nutrients every day (even on the days when morning sickness keeps you from eating a healthy diet).

Skip this:

  • Alcohol: This is the biggest pregnancy no-no. The experts maintain that there is no safe amount of alcohol during pregnancy—whatever you drink will pass through the placenta to the baby, potentially causing harm.
  • Sushi: Raw fish (or raw meat for that matter) should be avoided because it could be a source of harmful bacteria or parasites.
  • Soft cheese made from unpasteurized milk: Read the labels to see what’s safe. If the ingredients list pasteurized milk, then soft cheeses (like brie, feta or queso fresco) are okay to eat. But those made with unpasteurized milk could be contaminated with E. coli or Listeria.
  • Deli meats: Although these are precooked, they can be contaminated with Listeria, so it’s best to eat them only if you heat them to at least 165 degrees first.
  • Albacore (or white) tuna: This type of tuna has higher levels of mercury than light tuna. So best to switch to “light” for these nine months.
  • Sprouts: Since raw sprouts can harbor harmful E. coli or salmonella bacteria, it’s best to avoid them during your pregnancy.
  • Caffeine: The jury is out on whether or not you need to avoid caffeine entirely during your pregnancy, but since it can increase the baby’s heart rate and potentially slow growth, it’s best to limit your intake to no more than 200 milligrams per day.