Vaccination against influenza (if pregnancy occurs during a flu season) can be carried out at any time during pregnancy, and is recommended for all pregnant women and for each subsequent gestation.
The diphtheria, tetanus-pertussis vaccine (dTpa), recommended as a single dose during the third trimester of each pregnancy (27-32 weeks), is of great importance.
During pregnancy, the dTpa vaccine and the influenza vaccine can be administered simultaneously.
Even during the current situation with the novel Coronavirus (SARS-CoV-2), according to the World Health Organization (WHO), it is essential to keep vaccination appointments. This is especially true for recommended vaccinations, so long as the response measures for Covid-19 allow it.
In case of high risk of exposure to poliovirus (e.g. travel to endemic countries), the inactivated polio vaccine (IPV) can also be administered. In clearly indicated cases, clinical practice allows the administration of tetravalent vaccines. 

The influenza vaccine is recommended and offered for free to women at any time during their pregnancy. Seasonal influenza can increase the risk of complications, such as maternal hospitalization, premature birth, caesarean section, fetal distress, low birth weight and termination of pregnancy.

The influenza vaccine is recommended for prevention during the next season, which should start sometime in the second half of October 2020.

Pregnancy is one of the most delicate periods in a woman's life and there are never too many precautions. During the nine months of waiting and after childbirth, the woman, the fetus and the future baby are at a greater risk of infections. Thus, it's a good idea to get vaccinated. The vaccine protects you from the flu but also from its complications and consequences. Furthermore, the vaccine protects your baby thanks to your antibodies (produced after getting the vaccine) that pass to him/her through the placenta. Remember that babies cannot be vaccinated before the start of the third month of life (61st day), so the pregnancy influenza vaccine is the only way you can protect your child.

According to the new indications given by the Ministry of Health, the influenza vaccine can be administered at any stage of pregnancy before flu season starts (generally from late October to before Christmas). Keep in mind that approximately 2-3 weeks are needed before achieving an antibody response and this response must be complete before flu season peaks (generally late January-early February). The protection lasts throughout the season and you must get the influenza vaccine again with each new season because the virus changes every year.

Note: The influenza vaccine does not protect against Covid-19.

Pertussis is a very serious and very contagious infection. Infants and nursing babies have a greater risk of serious complications, especially in the first six months of life. Permanent neurological complications, pneumonia, respiratory failure and other conditions may arise that require hospitalization and that can even lead to death. In the first year of life, pertussis does not manifest as coughing attacks but instead as episodes of apnea during which the child stops breathing.

In general, the infection is transmitted by the mother herself or another close relative.

For this reason, pertussis vaccination (dTpa vaccine, or dTpa-polio where indicated) is strongly recommended during each pregnancy. It can also be administered in combination with the influenza vaccine.

The gynecologist is right. According to the new guidelines from the Ministry of Health, the best period during which to get the vaccine is between the 27th to 36th week of pregnancy, ideally during the 28th week because you can get a better maternal immune response during this period. Additionally, optimal passage of antibodies from the mother to the baby through the placenta is guaranteed. In any case, each period can be useful. Follow the indications given by your gynecologist.