Do pregnant women who have been vaccinated against COVID-19 have an increased risk of pregnancy loss?

Last updated: February 21, 2022
No. All the studies in this list that examine the question agreed on this conclusion. We identified one of these studies as a literature review, which is a type of study that reviews and often evaluates the findings of many studies on a question. This gives us more confidence that the answer is correct.
This short answer was generated by aggregating the answers that each of the studies below gave to the question (as indicated by State of K members) and adjusting for source quality and other factors. If key studies are missing or the answers attributed to individual studies are incorrect, the above answer could be wrong. For medical questions, don't rely on the information here. Consult a medical professional.
0
YES ANSWERS
7
NO ANSWERS
0
NO DATA ON ANSWER


Chart summary of 7 studies examining this question

All answers are assigned by State of K users. The label Couldn't Identify means that State of K was not able to determine whether a study answers the question "yes" or "no". This could be due to several factors. One possibility is that a study found some evidence to indicate that the answer to the question is "yes" and some evidence to indicate that the answer is "no". This often happens when a study uses two or more proxies to study the same phenomenon (i.e. firearm sales figures and self-reported firearm ownership rates as proxies for the prevalence of firearms) and the proxies yield different results when looking for correlations with another phenomenon (i.e. firearm-related deaths). Alternatively, the label may be applied if the phenomenon under study (i.e. whether breast milk improves cognitive function) is true for one group, but not another (i.e. true for girls, but not for boys). Yet another possibility is that a study found there was insufficient evidence to reach a conclusion regarding the question. Finally, the full text or abstract of a study may not have been written clearly or was inaccessible. This would make it difficult to determine how a study answered a question.

All labels of Literature Reviews and source quality are assigned by State of K. All labels of High Quality Source are assigned based on whether the publication in which the article appeared was ranked as Q1 by Scimago Institutions Rankings. Certain well-regarded think tanks are also given this label.

Literature Reviews
Although we recommend you consider all of the studies below, we believe the following study is a literature review, which surveys and evaluates many studies on this question:

SUMMARIES OF STUDIES
Total studies in list: 7
Sorted by publication year
1
COVID-19 and novel mRNA vaccines in pregnancy: an updated literature review
"The novel coronavirus, SARS-CoV-2, or COVID-19, has affected the world on a pandemic scale resulting in catastrophic outcomes and deaths. Currently, there is limited safety data specific to mRNA vaccine use in pregnant or lactating individuals and the potential risks to a pregnant individual and the fetus are unknown. We report an updated literature review of current information and evidence available to aid in the decision whether to vaccinate against COVID-19 currently being made by pregnant individuals and their healthcare providers so that they are able to make a well-informed recommendation and decision."
AUTHORS
CN Amin
AC Kekeh
E Joubert
PUBLISHED
2021 BJOG: An International Journal of Obstetrics & Gynaecology
Literature Review
High Quality Source
No
No
2
Receipt of mRNA Covid-19 Vaccines and Risk of Spontaneous Abortion
"As compared with data from two historical cohorts that represent the lower and upper ranges of spontaneous-abortion risk,2,4 the cumulative risks of spontaneous abortion from our primary and sensitivity analyses were within the expected risk range (Figure 1). Limitations of our study include the lack of a control group of unvaccinated pregnant persons, the homogeneity of the participants in terms of racial and ethnic groups and occupation, the voluntary enrollment of the population, and the use of data reported by the participants themselves, including some data collected retrospectively. Nonetheless, 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.5"
AUTHORS
Ashley N. Smoots
Lauren H. Zauche
Bailey Wallace
PUBLISHED
2021 The New England Journal of Medicine
High Quality Source
No
No
3
Spontaneous Abortion Following COVID-19 Vaccination During Pregnancy
"COVID-19 infection during pregnancy can be associated with severe maternal morbidity.1 In the United States, 1 COVID-19 vaccine has been approved and 2 have been authorized for use for pregnant women. To date, data on maternal COVID-19 vaccine safety come primarily from passive surveillance, and studies lack an unvaccinated comparison group.2,3 Spontaneous abortion has been identified as a priority outcome in studies of maternal vaccine safety,4 and concerns regarding risks of spontaneous abortion may be a barrier to vaccination during pregnancy. We present findings from case-control surveillance of COVID-19 vaccination during pregnancy and spontaneous abortion.MethodsThe Vaccine Safety Datalink is a collaboration between the Centers for Disease Control and Prevention and 9 health systems, representing approximately 3% of the US population.5 We applied a validated pregnancy algorithm, which incorporates diagnostic and procedure codes and electronic health record (EHR) data, to identify and assign gestational ages for spontaneous abortions and ongoing pregnancies.6 Data from 8 health systems (Kaiser Permanente: Washington, Northwest, Northern California, Southern California, and Colorado; Denver Health; HealthPartners; and Marshfield Clinic, Wisconsin) over seven 4-week surveillance periods from December 15, 2020, through June 28, 2021, were included. Ongoing pregnancies between 6 and 19 weeks’ gestation were identified on the last day of each 4-week surveillance period (index date) and contributed data to 1 or more surveillance periods. Spontaneous abortions were assigned to a 4-week surveillance period based on their outcome date; these spontaneous abortions could have been included in the ongoing pregnancy categories during prior periods (eFigure in the Supplement). Vaccination data came from EHRs, medical and pharmacy claims, and regional or state immunization information systems.We analyzed the odds of receiving a COVID-19 vaccine in the 28 days prior to spontaneous abortion compared with the odds of receiving a COVID-19 vaccine in the 28 days prior to index dates for ongoing pregnancies. Both spontaneous abortions and ongoing pregnancies were assigned to gestational age groups (6-8, 9-13, and 14-19 weeks), surveillance periods, site, maternal age groups (16-24, 25-34, and 35-49 years), number of antenatal visits (≤1 or ≥2), and race and ethnicity. Generalized estimating equations with binomial distribution and logit link were used to account for repeated ongoing pregnancies across surveillance periods. Analyses by manufacturer and gestational age group were also conducted. Analysis was performed using SAS/STAT software version 9.4 (SAS Institute Inc).This surveillance was approved by the institutional review boards of all participating sites with a waiver of informed consent.ResultsOf 105 446 unique pregnancies, 13 160 spontaneous abortions and 92 286 ongoing pregnancies were identified. Overall, 7.8% of women received 1 or more BN"
AUTHORS
Malini DeSilva
acob Haapala
Elyse O. Kharbanda
PUBLISHED
2021 JAMA
High Quality Source
No
No
4
COVID-19 vaccination in pregnancy: early experience from a single institution
"Objective: Pregnant women are at increased risk for morbidity owing to infection with the COVID-19 virus.1 Vaccination presents an important strategy to mitigate illness in this population. However, there is a paucity of data on vaccination safety and pregnancy outcomes because pregnant women were excluded from the initial phase III clinical trials. Our objective was to describe the maternal, neonatal, and obstetrical outcomes of women who received a messenger RNA (mRNA) COVID-19 vaccination while pregnant during the first 4 months of vaccine availability.Study design: This was an institutional review board-approved descriptive study of pregnant women at New York University Langone Health who received at least 1 dose of an mRNA COVID-19 vaccination approved by the US Food and Drug Administration (FDA) (Pfizer-BioNTech or Moderna) from the time of the FDA Emergency Use Authorization to April 22, 2021. Eligible women were identified via search of the electronic medical record (EMR) system. Vaccine administration was ascertained via immunization records from the New York State Department of Health. Women were excluded if they were vaccinated before conception or during the postpartum period. Charts were reviewed for maternal demographics and pregnancy outcomes. Descriptive analyses were performed using the R software version 4.0.2 (The R Foundation, Boston, MA).Results: We identified 424 pregnant women who received an mRNA vaccination. Of those, 348 (82.1%) received both doses and 76 (17.9%) received only 1 dose. The maternal characteristics and vaccination information are shown in Table 1. Of the included women, 4.9% had a history of a confirmed COVID-19 diagnosis before vaccination. After vaccination, no patient in our cohort was diagnosed with COVID-19. In terms of the pregnancy outcomes, 9 women had spontaneous abortions, 3 terminated their pregnancies, and 327 have ongoing pregnancies. Of the women included, 85 delivered liveborn infants. There were no stillbirths in our population. Of the 9 spontaneous abortions, 8 occurred during the first trimester at a range of 6 to 13 weeks' gestation. There was 1 second trimester loss. The rate of spontaneous abortion among women vaccinated in the first trimester was 6.5%. The 327 women with ongoing pregnancies have been followed for a median of 4.6 weeks (range, 0-17 weeks) following their most recent dose. A total of 113 (34.6%) women, initiated vaccination during the first trimester, 178 (54.4%) initiated vaccination during the second trimester, and 36 (11.0%) during the third trimester. Following the vaccination, 2 fetuses (0.6%) developed intrauterine growth restriction, whereas 5 (1.5%) were diagnosed with anomalies. Outcomes for the 85 women who delivered are shown in Table 2. Of the women who delivered, 18.8% were diagnosed with a hypertensive disorder of pregnancy. The rate of preterm birth was 5.9%. One preterm delivery was medically indicated, whereas the remaining 3 were spontaneous. A tot"
AUTHORS
Ashley S Roman
Christina A Penfield
Jennifer L Lighter
Valeryia Avtushka
Meghana A Limaye
Megan E Trostle
PUBLISHED
2021 American Journal of Obstetrics & Gynecology
No
No
5
Receipt of mRNA COVID-19 vaccines preconception and during pregnancy and risk of self-reported spontaneous abortions, CDC v-safe COVID-19 Vaccine Pregnancy Registry 2020-21
"Background There is continuing public concern about the safety of COVID-19 vaccination during pregnancy. While there is no compelling biological reason to expect that mRNA COVID-19 vaccination (either preconception or during pregnancy) presents a risk to pregnancy, data are limited. It is, however, well documented that SARS-CoV-2 infection during pregnancy is associated with severe illness and increased risk of adverse pregnancy outcomes. Among recognized pregnancies in high-income countries, 11-16% end in spontaneous abortion (SAB). Methods People enrolled in v-safe, a voluntary smartphone-based surveillance system, who received a COVID-19 vaccine preconception or during pregnancy were contacted by telephone to enroll in the v-safe pregnancy registry. V-safe pregnancy registry participants who received at least one dose of an mRNA COVID-19 vaccine preconception or prior to 20 weeks' gestation and who did not report a pregnancy loss before 6 completed weeks' gestation were included in this analysis to assess the cumulative risk of SAB using Life Table methods. Results Among 2,456 pregnant persons who received an mRNA COVID-19 vaccine preconception or prior to 20 weeks' gestation, the cumulative risk of SAB from 6-19 weeks' gestation was 14.1% (95% CI: 12.1, 16.1%). Using direct age standardization to the selected reference population, the age-standardized cumulative risk of SAB was 12.8% (95% CI: 10.8-14.8%). Conclusions When compared to the expected range of SABs in recognized pregnancies, these data suggest receipt of an mRNA COVID-19 vaccine preconception or during pregnancy is not associated with an increased risk of SAB. These findings add to accumulating evidence that mRNA COVID-19 vaccines during pregnancy are safe."
AUTHORS
Christine K Olson
Ashley N Smoots
Bailey Wallace
Lauren Head Zauche
PUBLISHED
2021 Research Square
No
No
6
Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons
"Background: Many pregnant persons in the United States are receiving messenger RNA (mRNA) coronavirus disease 2019 (Covid-19) vaccines, but data are limited on their safety in pregnancy.Methods: From December 14, 2020, to February 28, 2021, we used data from the "v-safe after vaccination health checker" surveillance system, the v-safe pregnancy registry, and the Vaccine Adverse Event Reporting System (VAERS) to characterize the initial safety of mRNA Covid-19 vaccines in pregnant persons.Results: A total of 35,691 v-safe participants 16 to 54 years of age identified as pregnant. Injection-site pain was reported more frequently among pregnant persons than among nonpregnant women, whereas headache, myalgia, chills, and fever were reported less frequently. Among 3958 participants enrolled in the v-safe pregnancy registry, 827 had a completed pregnancy, of which 115 (13.9%) resulted in a pregnancy loss and 712 (86.1%) resulted in a live birth (mostly among participants with vaccination in the third trimester). Adverse neonatal outcomes included preterm birth (in 9.4%) and small size for gestational age (in 3.2%); no neonatal deaths were reported. Although not directly comparable, calculated proportions of adverse pregnancy and neonatal outcomes in persons vaccinated against Covid-19 who had a completed pregnancy were similar to incidences reported in studies involving pregnant women that were conducted before the Covid-19 pandemic. Among 221 pregnancy-related adverse events reported to the VAERS, the most frequently reported event was spontaneous abortion (46 cases).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."
AUTHORS
Tanya R Myers
Shin Y Kim
Tom T Shimabukuro
PUBLISHED
2021 The New England Journal of Medicine
High Quality Source
No
No
7
Covid-19 Vaccination during Pregnancy and First-Trimester Miscarriage
"Our study found no evidence of an increased risk for early pregnancy loss after Covid-19 vaccination and adds to the findings from other reports supporting Covid-19 vaccination during pregnancy."
AUTHORS
Helena N. Eide
Håkon K. Gjessing
Maria C. Magnus
PUBLISHED
2021 The New England Journal of Medicine
High Quality Source
No
No