Pregnancy and breastfeeding

Compared to non-pregnant persons, SARS-CoV-2 infection in pregnancy is associated with increased risk of hospitalization and admission to an intensive care unit (ICU). SARS-CoV-2 infection during pregnancy is also associated with an increased risk in the neonate of preterm birth, low birth weight, and admission to a neonatal intensive care unit (NICU). Vaccination helps to protect the person who is pregnant and vaccination during pregnancy also lowers the risk of hospitalization for their newborn.

Recommendations

People who are pregnant or breastfeeding are recommended to be vaccinated as per the Recommendation for use section, with COVID-19 vaccination recommended for those 5 years of age and older who have not been previously vaccinated. Pregnancy is included in the group of previously vaccinated individuals for whom COVID-19 vaccination is particularly important.

An mRNA vaccine is preferred due to reassuring published data on the safety of these vaccines in pregnancy. COVID-19 vaccines can be given at any stage of pregnancy.

Considerations

Pregnant or breastfeeding individuals were excluded from COVID-19 vaccine clinical trials. However, analysis of data collected through international COVID-19 immunization registries to date have not revealed any maternal or neonatal safety signals.

Informed consent should include discussion that there is real-world evidence on the safety profile and effectiveness of mRNA vaccination with large numbers of individuals who are pregnant or breastfeeding, but that there is currently limited evidence on the use of the protein subunit vaccine.

Rates of adverse effects are similar in people who are pregnant or breastfeeding and those who are not pregnant or breastfeeding. Studies have not found any impacts of mRNA COVID-19 vaccination on the infant/child being fed human milk or on milk production or excretion. Vaccination during pregnancy does not increase risk for adverse pregnancy/birth outcomes, including miscarriage, stillbirth, low birth weight, preterm birth, and NICU admission.

Evidence suggests that COVID-19 mRNA vaccination during pregnancy results in comparable antibody titres to those generated in non-pregnant women. Maternal IgG humoral response to mRNA COVID-19 vaccines transfers across the placenta to the fetus, leading to a significant and potentially protective antibody titre in the neonatal bloodstream 1 week after the second dose. Infants of people who received the second dose of a primary series or a booster dose during pregnancy had a lower risk of hospitalization with COVID-19 (including Omicron) compared to infants born to individuals who were unvaccinated.

The effect was greater with the booster dose than the second dose in a primary series and if the dose was given later in the pregnancy as opposed to earlier. The protection from maternal vaccination against infant hospitalization decreases over time since birth.

Observational studies consistently show that both anti-spike IgG and IgA are present in breastmilk for at least 6 weeks after maternal vaccination with mRNA vaccines. The protection against disease as a result of breastfeeding is currently unknown.

Individuals who have received a COVID-19 vaccine during pregnancy are encouraged to enroll in a COVID-19 vaccine pregnancy registry (see Table 2).

There is a Canadian COVID-19 Vaccine Registry for Pregnant and Lactating Individuals, hosted at the University of British Columbia and supported by the COVID-19 Immunity Task Force (CITF) to assess the safety and effectiveness of COVID-19 vaccines.