Women between the age of 15 and 49 may reduce their risk of developing heart attacks, strokes, and hypertension by consuming fish right in omega 3 fatty acids. Compared to women eating fish high in omega 3 fats such as salmon, mackerel, cod and herring, have a 90% less risk compared to women eating little or no fish. This study was published in the journal, Hypertension, in December of 2011 and involved 49,000 over 8 years.
It still remains a problem that fish are high in mercury, which is highly toxic to the fetus. So, we do not recommend eating any fish during the year before and during pregnancy. It would make sense to use either fish or krill oil.