"Some fat is good for you. Oily fish, such as herring, sardines, salmon and mackerel, are rich in omega-3 essential fatty acids, which are key to the development of your baby's eyes and brain. Sixty percent if your baby's brain is, in fact, made up of essential fatty acids, so, it's particularly important to eat such foods during your last trimester, when your baby's brain increases in weight by four to five times. Essential fatty acids are good for you, too, as they have been linked with a reduced risk of high blood pressure during pregnancy. Pregnant women are advised to eat two portion of fish a week, one of which should be oily."