When analysing the potential impact of COVID-19 vaccines in pregnancy, first of all, we must observe that several studies have shown that, in pregnant women, SARS-CoV-2 infection can have significant negative consequences.
Thus, the INTERCOVID study (one of the largest to date, which included 706 pregnant women infected with SARS-CoV-2) showed that this infection (including asymptomatic forms) is associated with an increased risk of preeclampsia and eclampsia, secondary infections, hospitalization in intensive care, and medically induced preterm birth. Other studies from countries such as China, India, Iran, Spain and Turkey, have provided similar results. In addition, it was observed that new-borns by COVID-19-positive mothers had a lower birth weight than those of COVID-19 negative mothers.
Transplacental transmission of SARS-CoV-2 infection from mother to foetus is also possible, but still not completely understood. All these maternal and foetal risks associated with COVID-19 indicate the need for careful monitoring of pregnant women infected with SARS-CoV-2, as well as taking more rigorous prophylaxis measures—including vaccination—by pregnant women or those who are planning to become pregnant.
Safety of COVID-19 vaccines in pregnancy
In medical practice, most vaccines (such as those for the flu or whooping cough) are allowed and even recommended for pregnant women. This is is a well-established approach.
Data on the safety and efficacy of COVID-19 vaccination during pregnancy are limited because vaccine-producing pharmaceutical companies have excluded pregnant women from their clinical trials. However, such data has started to accumulate considerably in recent times. The information suggests that the benefits of vaccination against COVID-19 in pregnancy outweigh the known or potential risks. COVID-19 mRNA vaccines have been shown to generate strong immunity in pregnant and lactating women, similar to that found in all other vaccinated people.
None of the anti-SARS-CoV-2 vaccines contains a live virus and no one can develop COVID-19 from them, including pregnant women or their babies. On the contrary, some studies show that, after vaccination (especially in the third trimester of pregnancy), there is a transfer of antibodies from mother to foetus, both through the placenta and through breast milk; thus, vaccination can give both the mother and the new-born protection against COVID-19.
Preliminary data from December 2020 to February 2021, extracted from the V-safe and VAERS monitoring registries of the adverse effects of mRNA vaccines, revealed that the frequency of miscarriages, premature births or cases of low birth weight infants is similar to that generally observed in pregnant women before the COVID-19 pandemic. In other words, mRNA vaccines do not appear to be accompanied by an increased risk of maternal-foetal complications.
Recommendations for COVID-19 vaccines in pregnancy
In the United States, the Center for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices (ACIP), in collaboration with the American College of Obstetricians and Gynaecologists (ACOG) and the American Academy of Paediatrics, have put together multiple good practice guidelines which show that pregnant women should not be denied the opportunity to be vaccinated against COVID-19. The American Society for Reproductive Medicine (ARSM) and the Society for Maternal-Fetal Medicine (SMFM) also support the vaccination of all pregnant and lactating women.
The World Health Organization (WHO) claims that pregnant women can be vaccinated against COVID-19, after a preliminary discussion with their family doctor about the possible benefits and risks of vaccination. The WHO considers COVID-19 vaccines to potentially be of great help to pregnant women at high risk of SARS-Cov-2 infection, such as frontline health workers, those living in areas with a high incidence of COVID-19, and those with comorbidities (such as high blood pressure or diabetes) associated with an increased risk of developing a severe form of COVID-19.
The European Center for Disease Prevention and Control (ECDC) shows that all EU member states, except Bulgaria, recommend vaccination against COVID-19 in pregnant women. Most of these countries recommend vaccination only after the first trimester of pregnancy, and with an mRNA vaccine. Some states (Germany, Lithuania, Spain) have issued similar recommendations (mRNA vaccine) for breastfeeding women. The European Society of Human Reproduction and Embryology (ESHRE) also stresses that pregnant women should have access to vaccination, but recommends that the decision to vaccinate or not be made in consultation with a doctor, after considering the individual benefits and risks.
It is not yet clear whether women planning a pregnancy should wait for some time (weeks or months) after vaccination before trying to get pregnant. Some authors consider such a postponement prudent, the American and British guidelines do not support a postponement, while the WHO or EMA do not make any recommendations in this regard.
Pregnant women infected with the coronavirus have an increased risk of maternal-foetal complications compared to uninfected women. The data available to date do not indicate a negative impact of COVID-19 vaccination in the pre- and post-conception periods. As a result, vaccination against COVID-19 is usually recommended for all pregnant women, or for those who are breastfeeding or intend to become pregnant, unless, of course, there are contraindications (history of severe allergic reactions or hypersensitivity to the components of the vaccine).
It is preferable to use an mRNA vaccine (Pfizer/BioNTech or Moderna vaccines), as adenoviral vector vaccines (such as Astra-Zeneca and Johnson & Johnson vaccines) can rarely cause autoimmune thrombocytopenia, especially in young women. In pregnant women, it is more prudent to get vaccinated after the first trimester of pregnancy. Before deciding whether or not to get vaccinated, it may be helpful (but not mandatory) for these women to consult with their doctor, considering the individual risk/benefit ratio.
If fever occurs after vaccination, it should be kept under control with paracetamol, as maternal fever, regardless of the cause, is associated with an increased risk of foetal malformations.
Dr Liviu Segall is a primary care physician in internal medicine and nephrology at the Fresenius Nephrocare Dialysis Center, Iasi