Q Now I'm pregnant, do I need to avoid eating fish? I can't work out whether it's good for me and the baby because of the omega-3 it contains, or bad for us because of mercury contamination...

A Dr Carrie Ruxton, a dietitian at the Health Food Supplements Information Service, says: "Several nutrients are vital during pregnancy, particularly folic acid, omega-3 fatty acids and vitamin D.

"Oily fish is the richest food source of omega-3s and vitamin D, yet many pregnant women wrongly believe eating fish could be harmful to their babies due to possible contamination with mercury or other sea pollutants.

"However, this isn't the case, as reported in a recent study in the Journal of Allergy and Clinical Immunology. Norwegian researchers followed up 40,000 women five years after giving birth, reporting that their children's communication skills were significantly better if the mothers had eaten seafood while pregnant.

"The only fish to get the thumbs-down for mercury levels was fresh tuna. This positive news means pregnant women can safely have one portion of salmon, trout, mackerel or herring weekly.

"For those who don't eat fish, certain fish oil supplements are suitable during pregnancy - your pharmacist will be able to advise.

"Since other nutrients are needed to grow a healthy baby, it's essential for women to take 400mcg of folic acid prior to conception and for the first trimester. A daily 10mcg vitamin D supplement is also recommended during pregnancy and breastfeeding."