Pregnant, Breastfeeding Women and COVID-19 Vaccines

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Last reviewed
October 20, 2021

Pregnant & Breastfeeding Women and COVID-19 Vaccines

In the United States, Europe, the U.K., health agencies have published various COVID-19 vaccine recommendations for women who may become pregnant, pregnant women, and women breastfeeding children. 

The US Centers for Disease Control and Prevention (CDC) and the European Medicines Agency (EMA) say 'COVID-19 vaccination is recommended for all 12 years and older women, including pregnant women, breastfeeding, trying to get pregnant, or might become pregnant in the future. However, there is limited data available on the efficacy of COVID-19 vaccines in pregnancy.'

And 'pregnant women in Russia can get vaccinated when the benefits for the mother outweigh the risks for the fetus.' However, the U.K. says, 'Like all medicines, vaccines can cause common side effects.'

As of October 2021, the CDC reported about 33% of pregnant women in the USA were fully vaccinated. And on October 18, 2021, the CDC reported (200) pregnant women (vaccination status and related comorbidities not undisclosed) have died from COVID-19 since January 2020.

Since the week of August 7, 2021, when over 1,000 pregnant women were diagnosed with COVID-19, the weekly rate has decreased to 686 patients by the end of September 2021.

During the CDC Advisory Committee on Immunization Practices (ACIP) meeting on September 22, 2021, Dana Meaney-Delman, MD, MPH FACOG presented 'Updates on COVID-19 and Pregnancy'; Elyse O. Kharbanda, MD, MPH HealthPartners Institute, delivered 'Safety of COVID-19 Vaccination in Pregnancy, Interim Data from the Vaccine Safety Datalink'; and Christine Olson MD, MPH presented 'Updates from the v-safe COVID-19 vaccine pregnancy registry.' The ACIP recently posted an informative video on YouTube for further clarifications.

As of October 15, 2021, thirty-three countries do not recommend pregnant women receive a COVID-19 vaccine, according to the Maternal Immunization Tracker, produced by Johns Hopkins University.

Pregnant & Breastfeeding Women COVID-19 Vaccine Research-Based News

October 19, 2021 - Translational Science published the results from a new study: Fc receptor (FcR)-binding and antibody effector functions were induced with delayed kinetics in both pregnant and lactating women compared to non-pregnant women after the first vaccine dose, which normalized after the second dose. Vaccine boosting resulted in high FcR-binding titers in breastmilk. 

October 19, 2021 - A new study focused on 'a persistent bias toward higher prevalence and increased severity of COVID-19 in males. The underlying mechanisms accounting for this sex difference remain incompletely understood. Sexually dimorphic expression of placental Fc receptors, ISGs and proteins, and interleukin-10 was observed following maternal SARS-CoV-2 infection, with up-regulation of these features in placental tissue of pregnant individuals with male fetuses. Reduced maternal SARS-CoV-2-specific antibody titers and impaired placental antibody transfer were also observed in pregnancies with a male fetus. These results demonstrate fetal sex-specific maternal and placental adaptive and innate immune responses to SARS-CoV-2.

October 6, 2021 - The EMA's PRAC concluded that there is currently no evidence suggesting a causal relationship of menstrual disorders with the Spikevax vaccine.

October 1, 2021 - Provider Considerations for Engaging in COVID-19 Vaccine Counseling With Pregnant and Lactating Patients.

September 29, 2021 - The U.S. CDC issued a Health Advisory confirmed data from the COVID-19-Associated Hospitalization Surveillance Network in 2021 indicate that approximately 97% of pregnant women hospitalized (either for illness or for labor and delivery) with confirmed SARS-CoV-2 infection were unvaccinated.

September 21, 2021 - Women who receive an mRNA COVID-19 vaccine during pregnancy pass high levels of antibodies to their babies, reported a new study published in the American Journal of Obstetrics & Gynecology—Maternal-Fetal Medicine. These findings demonstrate transplacental antibody transfer following mRNA COVID-19 vaccination during pregnancy, with 100% of cord blood specimens having high levels of anti-S antibodies. Furthermore, given the combination of positive anti-S IgG and negative anti-N IgG, the neonatal antibodies were secondary to the vertical transfer of antibodies from maternal vaccination rather than natural infection.

September 17, 2021 - COVID-19 vaccine booster protection against confirmed infections and severe disease - data from Israel.

September 10, 2021 - The Robert Koch Institute in Germany that Standing Vaccination Commission now recommends an mRNA vaccination for pregnant women, from the second trimester of pregnancy, and for breastfeeding women. They said the decision was made "after detailed consultation and evaluation of the existing evidence." 

September 8, 2021 - The NEJM published - Receipt of mRNA Covid-19 Vaccines and Risk of Spontaneous Abortion. 'Our findings suggest that the risk of spontaneous abortion after mRNA Covid-19 vaccination either before conception or during pregnancy is consistent with the expected risk of spontaneous abortion; these findings add to the accumulating evidence about the safety of mRNA Covid-19 vaccination in pregnancy.'

September 8, 2021 - The PAHO reported more than 270,000 pregnant women have become sick with COVID in the Americas so far, and more than 2,600 have died from the virus. The problem is particularly acute in Mexico and Colombia, where COVID-19 has become the leading cause of maternal deaths in 2021.

September 8, 2021 - The JAMA Network published a Research Letter: Spontaneous Abortion Following COVID-19 Vaccination During Pregnancy. Finding: Among women with spontaneous abortions, the odds of COVID-19 vaccine exposure were not increased in the prior 28 days compared with women with ongoing pregnancies.

September 7, 2021 - The journal Nature Medicines published a new study: Effectiveness of the BNT162b2 mRNA COVID-19 vaccine in pregnancy. In summary, the BNT162b2 mRNA vaccine was estimated to have high vaccine effectiveness in pregnant women, similar to the general population's effects.

September 3, 2021 - Public Health England updated Green Book Chapter 14a to say 'pregnant women are more likely to have severe COVID-19 infection if they are overweight or obese, are minority ethnic background, have comorbidities such as diabetes, hypertension, and asthma, or are 35 years old or older.

August 25, 2021 - The benefits of the COVID-19 vaccine for pregnant women and their babies are backed by solid, ongoing research, according to UMass Medical School chair and professor of obstetrics & gynecology Tiffany A. Moore Simas, M.D., MPH, MEd.

August 24, 2021 - "Our findings show that vaccination results in a significant increase in antibodies against SARS-CoV-2 — the virus that causes COVID-19 — in breast milk, suggesting that vaccinated mothers can pass on this immunity to their babies, something we are working to confirm in our ongoing research," said Joseph Larkin III, Ph.D., senior author of the study and an associate professor at the University of Florida.

August 20, 2021 - Israel's Ministry of Health Director-General, Prof. Nachman Ash, authorized the Comirnaty mRNA vaccine for pregnant women.

August 20, 2021 - The Breastfeeding Medicine journal published Detection of SARS-CoV-2-Specific IgA in the Human Milk of COVID-19 Vaccinated Lactating Health Care Workers. This prospective observational study was conducted at Shands Hospital, University of Florida, from December 2020 to March 2021. Twenty-two lactating health care workers who received the mRNA vaccine (Comirnaty or SpikeVax) made up the sample group. The study's results show that the mRNA-based COVID-19 vaccines induce SARS-CoV-2-specific IgA and IgG secretion in human milk. However, further studies are needed to determine the duration of this immune response, its capacity to neutralize the SARS-CoV-2 virus, the transfer of passive immunity to breastfeeding infants, and the potential therapeutic use of human milk IgA to combat SARS-CoV-2 infections and COVID-19.

August 17, 2021 - Last update date of the Comirnaty Phase 2/3, randomized, placebo-controlled, observer-blind study evaluating the safety, tolerability, and immunogenicity of 30 µg of BNT162b2 or placebo administered in 2 doses, 21 days apart, in approximately 700 healthy pregnant women 18 years of age or older vaccinated at 24 to 34 weeks gestation. Participants will be randomized 1:1 to receive BNT162b2 or placebo (saline).

August 17, 2021 - The JAMA Network published a research letter: Short-term Reactions Among Pregnant and Lactating Individuals in the First Wave of the COVID-19 Vaccine Rollout. This large prospective cohort study found that COVID-19 vaccines were well-tolerated among pregnant, lactating, or planning pregnancy. However, all groups reported increased adverse reactions following dose two of BNT162b2 (Comirnaty) and mRNA-1273 (SpikeVax) vaccines. Among pregnant participants, any obstetrical symptoms were reported by 346 of 7809 individuals (4.4%) after the first dose and 484 of 6444 individuals (7.5%) after the second dose.

August 11, 2021 - The journal JAMA published findings from a large US-based study that found that women with COVID-19 who were giving birth had a mortality rate of 0.13% compared with women without COVID-19.

August 11, 2021 - The US Centers for Disease Control and Prevention published updated COVID-19 vaccinations for women, pregnant women, and breastfeeding women.

August 3, 2021 - The Canadian Medical Association Journal published a new study: Preterm birth and stillbirth rates during the COVID-19 pandemic: a population-based cohort study. INTERPRETATION: In Ontario, Canada, we found no special cause variation (unusual change) in preterm birth or stillbirth rates, overall or by subgroups, during the first 12 months of the COVID-19 pandemic compared with the previous 17.5 years.

July 30, 2021 - The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine announced their recommendation that all pregnant women be vaccinated against COVID-19. 

July 16, 2021 - A UC San Fransico study found 'Messenger RNA vaccines against COVID-19 were not detected in human milk, providing early evidence that the vaccine mRNA is not transferred to the infant.'

July 12, 2021 - A retrospective cohort study of pregnant women, the BioNTech - Pfizer (Comirnaty, BNT162b2) vaccine, was significantly lower risk SARS-CoV-2 infection with no vaccination.

July 8, 2021 - The U.K.'s NHS affirmed, 'If you're pregnant and have not had a COVID-19 vaccine yet, you should have the Pfizer/BioNTech or Moderna vaccine. And if you've already had the Oxford/AstraZeneca vaccine for your 1st dose and did not have any serious side effects, you should have it again for your 2nd dose. Furthermore, there's no evidence the COVID-19 vaccines have any effect on your chances of becoming pregnant.'

July 6, 2021 - The JAMA Pediatrics published a new study: Evaluation of mRNA From COVID-19 BTN162b2 and mRNA-1273 Vaccines in Human Milk. Results: Postvaccination milk samples were collected 4 to 48 hours after administering the BNT162b2 (n = 5) or mRNA-1273 (n = 2) vaccines. Analysis of 13 human milk samples collected 24 hours after vaccination, including multiple time points (4 to 48 hours) from a single participant, revealed that none of the samples showed detectable levels of vaccine mRNA in any component of the milk. However, clinical data from larger populations are needed to estimate the effect of these vaccines on lactation outcomes.

July 2, 2021 - The India Health Ministry announced that pregnant women are now eligible for Covid-19 vaccination at any time of the pregnancy. The Ministry has said that although most infected pregnant women (>90%) recover without the need for hospitalization, "rapid deterioration in health may occur in a few." However, it adds that most newborns (95%) of Covid-positive mothers have been in good condition at birth.

July 1, 2021 - Original paper: Short-term outcome of pregnant women vaccinated with BNT162b2 mRNA COVID-19 vaccine. Conclusions - The adverse-effect profile and short-term obstetric and neonatal outcomes among pregnant women who were vaccinated with the BNT162b2 vaccine at any stage of pregnancy do not indicate any safety concerns. The vaccine is effective in generating a humoral immune response in pregnant women, although SARS-CoV-2 IgG levels were lower than those observed in non-pregnant vaccinated women. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

June 29, 2021 - The U.S. CDC website stated, 'Based on how these vaccines work in the body, experts believe they are unlikely to pose a risk for people who are pregnant. However, there is currently limited data on the safety of COVID-19 vaccines in pregnant people. Human clinical trials that study the safety of COVID-19 vaccines and how well they work in pregnant people are underway or planned.

June 23, 2021 - A new observational study named MOMI-VAX has begun to evaluate the immune responses generated by COVID-19 vaccines administered to 750 pregnant or 250 postpartum women, announced by the National Institutes of Health.

June 23, 2021 - The Nature journal published: COVID vaccines and breastfeeding.

June 17, 2021 - The NEJM journal published a new study: Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons. CONCLUSIONS: Preliminary findings did not show obvious safety signals among pregnant persons who received mRNA Covid-19 vaccines. However, more longitudinal follow-up, including follow-up of large numbers of women vaccinated earlier in pregnancy, is necessary to inform pregnancy and infant outcomes maternally. However, more longitudinal follow-up, including follow-up of large numbers of women vaccinated earlier in pregnancy, is necessary to inform maternal, pregnancy, and infant outcomes.

June 15, 2021 - The U.S. CDC posted 'COVID-19 Vaccination Coverage Among Pregnant Women During Pregnancy — Eight Integrated Health Care Organizations, United States, December 14, 2020–May 8, 2021.' As of May 8, 2021, 16.3% of pregnant women identified in CDC's Vaccine Safety Datalink had received ≥one dose of a COVID-19 vaccine during pregnancy in the United States. Vaccination was lowest among women aged 18–24 years (5.5%) and highest among women aged 35–49 years (22.7%).

June 4, 2021 - The first Covid-19 vaccine study for pregnant women has been launched across the U.K. The study, which involves the University of Edinburgh's MRC Centre for Reproductive Health, occurs across 11 sites, including the Royal Infirmary of Edinburgh, with more than 200 UK participants. Participants will initially receive two doses of the Pfizer-BioNTech vaccine or a placebo with a gap of 21 days between them.

May 28, 2021 - Canada's National Advisory Committee on Immunization preferentially recommends that a complete two-dose vaccine series with an mRNA COVID-19 vaccine (Pfizer-BioNTech, Moderna) be offered to women who are pregnant or breastfeeding. If they cannot receive an mRNA vaccine, another authorized COVID-19 vaccine should be offered because of an allergy.

May 28, 2021 - The Royal College of Obstetricians and Gynaecologists updated its FAQs to include: The latest advice from the Joint Committee on Vaccination and Immunisation (JCVI) is that COVID-19 vaccines should be offered to pregnant women. Women may wish to discuss the benefits and risks of having the vaccine with healthcare professionals and reach a joint decision based on individual circumstances. And mothers should not stop breastfeeding to be vaccinated against COVID-19. Women trying to become pregnant do not need to avoid pregnancy after vaccination, and there is no evidence to suggest that COVID-19 vaccines will affect fertility.

May 24, 2021 - A new study found during March 29, 2020–March 5, 2021, underlying medical conditions were associated with an increased risk of moderate-to-severe or critical COVID-19 illness among pregnant women. Among 7,950 pregnant women with a SARS-CoV-2 virus infection (42.0% were Hispanic, and 54.5% had Medicaid), moderate-to-severe or critical COVID-19 illness was associated with age 25 years and older, healthcare occupation, pre-pregnancy obesity (28.2%), chronic lung disease, chronic hypertension (10%), and pregestational diabetes mellitus (10%). The risk of moderate-to-severe or critical illness increased with the number of underlying medical or pregnancy-related conditions. Two health conditions were associated with a 59% increased risk, and three or more conditions were associated with more than twice the risk compared to women without any reported conditions. This study did not disclose any related mother or infant fatalities.

May 13, 2021 - The Lancet published an exploratory analysis of a convenience sample, receipt of a COVID-19 messenger RNA vaccine was immunogenic in pregnant women, and vaccine-elicited antibodies were transported to infant cord blood and breast milk. Pregnant and non-pregnant women who were vaccinated developed cross-reactive antibody responses and T-cell responses against SARS-CoV-2 variants of concern.

May 11, 2021 - A limited study by researchers at Northwestern Medical in Chicago of vaccinated pregnant patients reported no observed increase in the incidence of findings characteristic of SARS-CoV-2 infection in pregnancy and no evidence of a vaccine-triggered breakdown in maternal immunologic tolerance of the fetus.

May 11, 2021 - Study: In-Hospital Mortality in a Cohort of Hospitalized Pregnant and Non-pregnant Patients With COVID-19. Overall and within multiple subgroups, we found a substantially lower in-hospital mortality rate in pregnant patients than non-pregnant patients hospitalized with COVID-19 and viral pneumonia, according to a new study by researchers with The University of Texas Health Science Center at Houston and the University of Maryland School of Medicine.

April 29, 2021 - Infants born to women with COVID-19 have a low chance of contracting the disease from their mothers, according to a study published in JAMA. "Our study suggests that mother and baby can be cared for together and that nursing can be recommended without danger to the baby's health," concluded first study author Mikael Norman, MD, in a Karolinska Institutet press release.

April 23, 2021 - A new study published in JAMA Network Open, physician-researchers from Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Children's Hospital, and Massachusetts General Hospital reveal mother-to-newborn transmission of the coronavirus is rare. Out of the 255 neonates studied, 88.2 percent were tested for SARS-CoV-2, and only 2.2 percent had positive results. 

April 21, 2021 - The NEJM Original Article: Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons. CONCLUSIONS: Preliminary findings did not show obvious safety signals among pregnant persons who received mRNA Covid-19 vaccines. However, more longitudinal follow-up, including follow-up of large numbers of women vaccinated earlier in pregnancy, is necessary to inform maternal pregnancy and infant outcomes.

April 13, 2021 - A non-peer-reviewed study: Ovarian follicular function is not altered by SARS-Cov-2 infection or BNT162b2 mRNA Covid-19 vaccination. Conclusions and relevance Both SARS-COV-2 infection and vaccination with the BNT162b2 mRNA vaccine mediate IgG immunity that crosses into the follicular fluid. No detrimental effect on follicular function was detected.

April 12, 2021 - JAMA published a Research Letter that found robust secretion of SARS-CoV-2 specific IgA and IgG antibodies in breast milk for 6 weeks after vaccination. IgA secretion was evident as early as 2 weeks after vaccination, followed by a spike in IgG after 4 weeks (a week after the second vaccine).

March 24, 2021 - This Practice Advisory was developed by the American College of Obstetricians and Gynecologists' Immunization, Infectious Disease, and Public Health Preparedness Expert Work Group. Information and recommendations will evolve as more data are collected about these vaccines and guidance for their use in pregnant and lactating patients.

March 12, 2021 - A non-peer-reviewed study's findings highlight that vaccination of pregnant women may provide maternal and neonatal protection from SARS-CoV-2 infection.

February 10, 2021 - Dr. Aya Mohr-Sasson, Sheba Medical Center, Israel, launched a clinical study with 200 women using the mRNA vaccines, evaluating their influence on the ovarian reserve.

February 9, 2021 - mBio published a study: Characterization of SARS-CoV-2 RNA, Antibodies, and Neutralizing Capacity in Milk Produced by Women with COVID-19. 'Our data do not support mother-to-infant transmission of SARS-CoV-2 via milk. Importantly, milk produced by infected mothers is a beneficial source of anti-SARS-CoV-2 IgA and IgG and neutralizes SARS-CoV-2 activity. These results support recommendations to continue breastfeeding during mild-to-moderate maternal COVID-19 illness.'

February 9, 2021 - Emer Cooke, EMA Executive Director and Chair of the International Coalition of Medicines Regulatory Authorities, published a Pregnancy and Lactation Workshop.

February 2, 2021 - Pregnant and recently pregnant women with covid-19 attending or admitted to the hospitals for any reason are less likely to manifest COVID-19 symptoms and are more likely to be admitted to the intensive care unit. Pre-existing comorbidities, non-white ethnicity, chronic hypertension, pre-existing diabetes, high maternal age, and high body mass index are risk factors for severe covid-19 in pregnancy. 

May 22, 2020 - A limited study published by Northwestern University COVID-19 reported that placentas showed an increased prevalence of decidual arteriopathy and other features of MVM, a pattern of placental injury reflecting abnormalities in abnormalities oxygenation within the intervillous space associated with adverse perinatal outcomes. These changes may reflect a systemic inflammatory or hypercoagulable state influencing placental physiology.

Note: This information has been aggregated from the US CDC, US FDA, WHO, EMA, and other research-based organizations.