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COVID-19, Vaccines and Pregnancy

Public Health Services Health Advisory: COVID-19 Vaccination for Pregnant People to Prevent Serious Illness, Deaths, and Adverse Pregnancy Outcomes from COVID-19

San Diego Perinatal Center strongly recommends COVID-19 vaccination for our patients, and the Centers for Disease Control and Prevention are now recommending all pregnant women receive the COVID-19 vaccine, regardless of gestational age.

CDC data indicates pregnant women with COVID-19 are more likely to experience preterm birth and other adverse pregnancy outcomes, and are at a higher risk for developing severe illness. Conditions such as diabetes, obesity, asthma, hypertension, sickle cell disease, thalassemia and kidney disease further increase risk.

The current efficacy and safety profiles of the messenger RNA, or mRNA, vaccine options from Pfizer-BioNTech and Moderna make them preferable to the Johnson & Johnson vaccine, which uses an inactivated adenovirus. The CDC tracks safety outcomes of individuals receiving COVID-19 vaccines from the following monitoring programs:

As of Aug. 16, 2021, v-safe has registered more than 148,000 pregnant vaccine recipients. No safety concerns for the recipients or their babies have been found to date. In the United States overall, the CDC vaccine tracker shows that about 360 million doses have been administered and 170 million people have been fully vaccinated as of Aug. 2021. In addition, a study published Aug. 18, 2021 in the journal Health Affairs estimates that COVID-19 vaccines prevented approximately 140,000 deaths and three million infections between late Dec. 2020 and early May 2021.

How COVID-19 mRNA Vaccines Work

Pfizer-BioNTech and Moderna’s two-dose vaccine options use mRNA, which teaches the body how to make proteins, to help the body create the spike proteins seen on the virus that causes COVID-19. The immune system then recognizes the proteins as foreign and develops antibodies to target the viral element of the spikes. If the body is exposed to the actual virus, its existing antibodies can either reduce the severity of infection or prevent it altogether. It takes two weeks after the second vaccine dose for the immune system to fully recognize the spikes and develop an effective antibody response.

Why mRNA Vaccines Can be Developed Faster

The goal of a vaccine is to train the immune system to recognize viruses and make antibodies that prevent infection. Most vaccines introduce a weakened or inactivated version of a virus so the body can make antibodies to detect and defeat the live virus. Traditional vaccines require significant production of animal cells that are then infected with a weakened or dead virus. This process takes four to six weeks. Because mRNA vaccines do not require infected cells and use highly regulated processes and purified ingredients, they can be synthesized quickly.

Why mRNA Vaccines for COVID-19 are not Considered Experimental

mRNA vaccine technology has been well-studied, which allowed it to be quickly deployed for use in COVID-19 vaccines. Before granting emergency use approval, the Food and Drug Administration reviewed data from clinical trials with tens of thousands of participants to determine vaccine efficacy and safety. These clinical trials were conducted according to the same rigorous standards used for medications and other vaccines. The Pfizer-BioNTech vaccine now has full FDA approval, with full approval expected for the Moderna vaccine in Sept. 2021.


Reliable, up-to-date information about COVID-19, including infection rates and vaccination recommendations, can be found from the following resources. This information is continually being reviewed and updated. San Diego Perinatal Center continues to monitor and update our recommendations based on these evidence-based resources.