The diseases that vaccines protect against are very dangerous, although some might think they are not ("I didn't get one and nothing happened to me"). None of the diseases protected against by a vaccine have disappeared, although they are no longer seen precisely because vaccination coverage has kept infection to a minimum. If you do not get vaccinated, you expose yourself and your unborn child to serious and totally unjustified risk. Vaccines are a very useful precaution and an investment in your health. Vaccines not only protect against the diseases for which they are made but also from the complications and the consequences of those diseases, which can be more or less intense based on your general health conditions.

The vaccines used for pregnant women consist of proteins synthesized in the laboratory that simulate the microorganism or virus, but they are not the infectious agent itself. Thus, they cannot harm the mother or the baby in any way. This is why the current vaccines are safe. There is no scientific evidence whatsoever that shows risk related to vaccination of pregnant women using inactivated microorganism vaccines. On the contrary, the maternal antibodies created in response to the vaccine pass to the unborn child through the placenta and reduce the risk of preventable infections in the first weeks of life when the newborn's immune system is still immature.
The scientific studies done have not documented any significant side effects after getting a vaccine. Thus, you can get vaccinated without worrying about anything.

La maggiore sensibilità vale sia per la futura mamma che per il neonato. L’“immunizzazione materna” ovvero la vaccinazione effettuata in gravidanza rappresenta una strategia piuttosto recente che permette di proteggere sia la donna, sia il feto che il futuro neonato da alcune infezioni prevenibili con il vaccino.

Attualmente, in gravidanza sono raccomandate le vaccinazioni contro influenza, tetano, pertosse (dTpa) e  difterite.  Il vaccino della poliomielite inattivato (IPV), pur non essendo raccomandato di routine, può essere somministrato a donne in gravidanza ad alto rischio di esposizione al poliovirus (per es. in caso di viaggi in paesi endemici).
Per maggiori informazioni, leggi le FAQ della sezione “QUALI VACCINI IN GRAVIDANZA? L’attuale immunizzazione materna”.

The maternal antibodies (IgG) are transferred through the placenta (transplacental transmission) and provide passive immunity to infants during the first months of life, until the first immunizations are administered, or at least until the end of the period when they are most sensitive to the infections covered by vaccines.
The transmission of antibodies through the placenta is a selective, active and intracellular process that starts at the 17th week of pregnancy and progressively increases until the 40th week, when the fetus antibodies reach higher levels than the maternal ones.