**Conflict of interest**

*Human Papillomavirus*

immunization for maternal antibodies [119, 127]. Though, the clinical importance of this blunting effect is unknown, the epidemiological data of implemented maternal immunization from various countries have not shown any negative impact

Gardasil and Cervarix both HPV vaccines are recombinant which contains virus-like particles (VLP's) and enhanced by an adjuvant which is responsible for triggering an immune response higher than a natural infection [129]. Gardasil 9, a 9-valent HPV vaccine was only licensed for use in the USA in December 2014. Depending on age, full coverage by the HPV vaccine is obtained by 2 or 3 doses with the first dose administered at time o, followed by the second dose after 1–2 months and the third dose after 6 months [130]. While, all doses are not received by many girls [131]. In order to achieve long-term duration of immunity,

Worldwide, millions of doses of HPV vaccine since its introduction have been administered and involuntary administration also occurs during pregnancy as the young fertile women are the main recipients of the vaccines. Potentially harmful adverse effects (AE) to the unborn child such as preterm birth, miscarriage, congenital malformations, fetal death or fears of teratogenicity raise concern among both the health care providers and recipients. The development of sensitive organs such as the heart, the central nervous system takes place in the first trimester of pregnancy and in this period the environmental factors like medications and drugs theoretically might cause damage the developing fetus which is the main reason of concern. The vaccine manufacturers (Merck and GlaxoSmithKline) and the World Health Organization recommend avoiding HPV vaccination during pregnancy [36]. However, in case of accidental vaccination of pregnant women there are no interventions and no mandatory pregnancy testing before vaccination recommended so far. Moreover, conducting studies to investigate the pregnancy outcomes by administering HPV vaccines to pregnant women are not ethically feasible. In pregnancy, the true safety of the HPV vaccination has not yet been established through randomized controlled trial. Hence, the HPV vaccine administration to the pregnant

In pregnant women, many observational studies reported the HPV infection risk but there are controversial results too. Higher HPV prevalence has been reported in few studies, whereas several studies reported lower prevalence in pregnant women or there is no statistical difference between pregnant and age matched non-preg-

For a successful pregnancy, a modulated, dynamic and responsive immune system is required but definitely not a suppressive one and this has been supported by an increasing number of studies. At the feto-maternal interface, the trophoblastic cells are important for the receptive immune system establishment which is achieved as a part of response mechanism to the normal microbiota which highlights the complexity of the regulatory pathways involved during pregnancy. Moreover, there are evidences on the effects that changed the modulated immune system and the receptive feto-maternal interface by a clinically silent viral infection emphasizes the necessity of better detection, treatment and prevention of the viral infections during pregnancy. This will further lead not only to the better outcomes

the repeat doses of vaccine are given which boost the immune system.

on the protection against the diseases targeted [26, 128].

**6.2 HPV vaccination during pregnancy**

women has not yet been approved [132].

**7. Conclusion**

nant controls [16].

**78**

The authors declare no conflict of interest.
