In periods of seasonal influenza, during pandemic flu in the past and from recent experience that we have the emergence of influenza A (H1N1), pregnant compared with non-pregnant women are at increased risk to get sick and to develop serious complications up to mortality. Purpose: This paper examines the risks that arise for pregnant from contamination with the flu virus and the safety of influenza vaccination in pregnancy. Method: The method involves searching review and research studies in Pubmed data base mainly of the 2000 until 2009 and the words were used is pregnancy, flu vaccination, complications of the flu vaccination at the period of pregnancy. Results: Morbidity during periods of seasonal influenza in pregnant women is increased, while in times of pandemic are recorded fatalities. Based on this, specific recommendations have been made for a flu vaccination in pregnant women, both from the CDC, the American College of Obstetricians and Gynecologists in the U.S. and other official bodies like the World Health Organization, according to that the constitution of influenza vaccine in the pregnancy is necessary, given that the probability of morbidity in this period is increased at 10%. Conclusions: The studies so far to influenza vaccination in pregnancy, do not record serious complications for pregnant women and infants. However more research needs to be done on the safety of influenza vaccination in pregnancy.