The potential impact of maternal immunization as a public strategy to prevent disease in mothers and infants is well recognized. Yet, there are no vaccines currently approved or licensed specifically for use in pregnant women. Licensed vaccines that are recommended for non-pregnant adults may be administered to pregnant women based on need and a risk:benefit assessment. When the risk of exposure and disease from a vaccine preventable infection is high for a mother and/or her fetus, and an effective vaccine is available, the benefit of the vaccine protection is greater than any potential theoretical risk from the vaccine, which is in turn considered to be lower than the risk of acquiring the infection and disease the vaccine can prevent. Licensed vaccines that have not been formally evaluated in or approved for pregnant women are therefore recommended for administration during pregnancy by the WHO and the US Centers for Disease Control and Prevention (CDC), as well as local organizations in many countries (1, 2) (Table 1). These recommendations have evolved over time, and they differ in that the current WHO recommendations do not specifically recommend pertussis vaccination during pregnancy, except when there is a known high burden of disease, as implemented in several countries such as Canada and Australia; while CDC and other Public Health programs such as in the UK, recommend routine vaccination of all pregnant women with the tetanus, diphtheria, and reduced acellular pertussis antigen content (Tdap) vaccine for all women, at every pregnancy. The specific timing of administration of this vaccine is also variable in different countries. Similarly, while tetanus vaccination is recommended for all pregnancies by WHO, most industrialized countries in Europe and North America, where pediatric vaccination coverage is high and the risk of tetanus infection at birth is negligible, do not routinely recommend tetanus vaccine administration during pregnancy. It is only given now because of the use of Tdap. Finally, influenza vaccination during pregnancy is considered an essential element of prenatal care in the US, and pregnant women have one of the highest influenza vaccination coverage rates in this country. However, while pregnant women are not excluded from influenza vaccination, routine administration is not the standard in most countries.