Tuna

"Yes, but try to limit the amount of tuna you eat during pregnancy. The same applies when you’re breastfeeding or trying for a baby. Experts recommend that you eat no more than the following each week: four medium-sized cans of tuna (with a drained weight of 140g, or 5oz, per can) OR two fresh tuna steaks (weighing about 170g, or 6oz, raw or 140g when cooked) So, if you have both types of tuna, you could have two cans and one steak a week but no more than this.  The reason for these limits is that tuna contains mercury, which won’t harm you, but too much of it can harm your baby’s developing nervous system."