All pregnant women are recommended to receive the inactivated influenza vaccine irrespective of their stage of pregnancy.
There is good evidence that pregnant women are at increased risk from complications if they contract influenza. In addition, there is evidence that having influenza during pregnancy may be associated with premature birth and smaller birth size and weight, and that influenza vaccination may reduce the likelihood of prematurity and smaller infant size at birth associated with an influenza infection during pregnancy. Furthermore, a number of studies show that influenza vaccination during pregnancy provides protection against influenza in infants in the first few months of life.
A review of studies on the safety of influenza vaccine in pregnancy concluded that inactivated influenza vaccine can be safely and effectively administered during any trimester of pregnancy and that no study to date has demonstrated an increased risk of either maternal complications or adverse fetal outcomes associated with inactivated influenza vaccine.
For more information please see the NHS Guidance below: