Pregnant and breastfeeding women must consult their doctors before being vaccinated against covid-19

Pregnant and breastfeeding women were excluded from clinical trials and there are few data about the efficacy and safety for this collective


Vaccines against covid-19 have not yet been recommended in a universal way for pregnant and breastfeeding women because they were excluded from the clinical trials and there are few data about the efficacy and safety for this collective. However, no notice has been issued discouraging them from being immunised. Manufacturers and sanitary authorities indicate for the moment that women must consult with their doctors to assess the benefits and risks of vaccination based on their potential risk of exposure to the virus or whether they have a previous medical condition that could jeopardise their condition in case of infection. Ultimately, the decision of being vaccinated rests with women.

Pregnant women are a group of risk that can undergo a more severe covid-19 symptomatology that non-pregnant women and suffer complications due that pregnancy itself decreases the immune capacity, accelerates the cardiac frequency, modifies the pulmonary capacity due to an increasing oxygen consumption also increasing the possibilities of suffering thrombi, explains to Verificat Cyril Huissoud, general secretary of the National Society of Gynaecologists and Obstetricians in France. Complications increase if women have previous pathologies. Even so, the risk of suffering a serious illness derived from SARS-CoV-2 is estimated to remain low.

Large-scale data are missing

The lack of international consensus to establish directrices for this collective leads to disparate advice. The American College of Obstetricians and Gynecologists (ACOG) underlies that pregnant women must not be excluded from the immunisation campaign and that vaccines must be offered to breastfeeding women in the same measure that are offered to the non-breastfeeding ones. The Spanish Health Ministry, however, is recommending to postpone vaccination of pregnant women until the end of gestation, although it advises that each woman assess in an individual manner her exposure risk to the exposition or to suffer complications.

Pregnant women are not vaccinated in an usual manner

Generally, women within the gestation months are not being vaccinated, explains Huissoud. But there is a family of vaccines totally unadvised for pregnant women: that of live viruses which contain a weakened version of the pathogen, according to the specialist. “A precautionary principle is applied because we are considering whether there are risks with viruses that have a reputation of causing malformations in foetuses, as is the case of the vaccine against rubella”, he says. However, none of the authorised vaccines against covid-19 is made from live viruses, as Huissoud recalls, so none of the existing ones should cause any problems. Moreover, “preliminary data [about the vaccines against covid-19 and pregnancy] are reassuring”, he points out. The studies of Pfizer-BioNTech, Moderna and Janssen in lab animals before and after gestation did not detect safety problems.

New encouraging data

A study published on 21 April in the specialised journal New England Medical Journal shed preliminary encouraging data about the safety of Pfizer-BioNTech and Moderna formulas, created with the mRNA technology, which could help women to take the decision of being vaccinated. The clinical trial, in which 35.691 women between 16 and 54 years old participated in the United States, determined that abortion rates, premature labor mand other complications were comparable to those observed in pregnant women before the pandemic. The authors of the investigation advise, nonetheless, to realise more studies about the monitoring to a larger number of vaccinated women in the first pregnancy stages to obtain further data during gestation and breastfeeding.

Another study carried out by US scientists and published on 25 March proved the efficacy of mRNA vaccines in pregnant and breastfeeding women. The results determined that these vaccines transferred antibodies to their children through the placenta and the breast milk. Despite only 131 people participating in the clinical trial, a very small representative sample , it is considered as an important finding about the benefits of the immunisation of this group and their children.