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A.A US Food and Drug Administration panel have recently recommended that pregnant women should limit their consumption of tuna, and avoid completely swordfish, shark, tilefish and king mackerel. This is because of concerns that these particular fish may contain levels of mercury that could be harmful to developing babies. Mercury enters the sea environment through pollution. Virtually all fish contain tiny amounts of mercury. Long–lived fish that are predators, such as shark or swordfish accumulate the greatest amounts of mercury and so might be harmful to people who eat them regularly. The safe level of tuna intake with regard to the effects of mercury in pregnancy has not been established, but in the meantime it has been recommended that pregnant women should eat no more than two six-ounce cans of tuna each week. However, women should not avoid all fish completely as fish is a rich source of protein and fatty acids, important for both the mother and the developing baby. Fish such as salmon, for example, are considered safe. In addition, a high fish intake is associated with less risk of pregnancy complications such as premature labour or a low birth weight baby. So fish remains a valuable component of a healthy diet in pregnancy.

Pregnancy complications may predict mothers at risk of heart disease later in life

Emerging evidence suggests that a link exists between pregnancy complications, such as preeclampsia, and later vascular disease, such as heart attacks, in the mother.

One study suggests that women who give birth to a low-birthweight (less than 2500g) baby are 7-11 times more likely to die from heart disease than women who give birth to an infant weighing 3500g or more at birth. Other studies suggest that women who have had preeclampsia during pregnancy are more likely to develop heart disease than women who do not develop this complication. In addition, women who have had a premature delivery, before 37 weeks' , may have twice the usual risk of heart disease.

If these associations are confirmed in bigger studies, then women who experience these pregnancy complications could benefit from screening for heart disease and preventive treatment, including lifestyle modifications such as better diet and increased exercise. Indeed there is some evidence to show that exercise during early pregnancy or before pregnancy can also reduce the likelihood of pregnancy complications.

*Reference: N Sattar & IA Greer, BMJ 2002; 325:157-60.