Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccination in Pregnancy: Measures of Immunity and Placental Histopathology

Perceptions and acceptance of COVID-19 vaccine among pregnant and lactating women in Singapore: a pre-vaccine rollout cross-sectional study

INTRODUCTION

Vaccination is critical in controlling the coronavirus disease 2019 (COVID-19) pandemic. However, vaccine perception and acceptance among pregnant and lactating women is unknown in Singapore. We aimed to determine the acceptance of COVID-19 vaccination among these two groups of women in Singapore and the factors associated with vaccine acceptance.

METHODS

We conducted an anonymous, online survey on the perceptions of the COVID-19 vaccine and its acceptance by pregnant and lactating women at a tertiary maternal and child hospital in Singapore from 1 March to 31 May 2021. Information on their demographics and knowledge was collected. These factors were assessed for their relationship with vaccine acceptance.

RESULTS

A total of 201 pregnant and 207 lactating women participated. Vaccine acceptance rates in pregnant and lactating women were 30.3% and 16.9%, respectively. Pregnant women who were unsure or unwilling to take the vaccine cited concerns about safety of the vaccine during pregnancy (92.9%), while lactating women were concerned about its potential long-term negative effects on the breastfeeding child (75.6%). Factors that were positively associated with vaccine acceptance included a lower monthly household income or education level, appropriate knowledge regarding vaccine mechanism and higher perceived maternal risk of COVID-19. Most pregnant (70.0%) and lactating women (83.7%) were willing to take the vaccine only when more safety data during pregnancy and breastfeeding were available.

CONCLUSION

COVID-19 vaccine acceptance was low among pregnant and lactating women in Singapore. Addressing the safety concerns when more data are available and education on the mechanism of vaccine action will likely improve acceptance among these women.

Safety of COVID-19 Vaccination in Pregnancy: A Systematic Review

The COVID-19 pandemic has posed significant risks to pregnant women and those recently pregnant, leading to heightened mortality and morbidity rates. Vaccination has emerged as a pivotal strategy in reducing COVID-19-related deaths and illnesses worldwide. However, the initial exclusion of pregnant individuals from most clinical trials raised concerns about vaccine safety in this population, contributing to vaccine hesitancy. This review aims to consolidate the existing literature to assess the safety and efficacy of COVID-19 vaccination in pregnant populations and neonatal outcomes. Diverse studies were included evaluating various aspects of safety for women and their newborns, encompassing mild to severe symptoms across different vaccines. The findings indicate the overall safety and efficacy of COVID-19 vaccination, with minimal adverse outcomes observed, including mild side effects like pain and fever. Although most studies reported the absence of severe adverse outcomes, isolated case reports have raised concerns about potential associations between maternal COVID-19 vaccination and conditions such as fetal supraventricular tachycardia and immune-mediated diseases. Our review underscores the importance of ongoing surveillance and monitoring to ensure vaccine safety in pregnant women. Overall, COVID-19 vaccination during pregnancy remains a safe and effective strategy, emphasizing the need for continued research and vigilance to safeguard maternal and fetal health.

Systematic Review: Safety and Efficacy of mRNA COVID-19 Vaccines in Pregnant Women

Since pregnant women were excluded from clinical trials for vaccines against SARS-CoV-2, the novel coronavirus disease 2019 (COVID-19), there is limited data on the safety and efficacy of vaccines in this population. This systematic review explored the safety and efficacy of mRNA vaccines in pregnant women. A literature search was performed using Ovid databases through November 2021 for all studies evaluated efficacy and safety of mRNA COVID-19 vaccines in pregnant women. A total of five studies including 42,782 women were included in the systematic review. Humoral immunity to COVID-19 was detected in pregnant women who received the vaccine and no differences found in spike-specific T-cell responses. Incidence of high-grade chronic villitis is higher in the unvaccinated group with adjusted odds ratio of .31 (.1-.97), P < .05. Vaccination in pregnant women resulted in 12.6% spontaneous abortions (SAB) with 92.3% occurring in the first trimester, .1% stillbirth (>20 weeks gestation), 9.4% preterm birth (<37 weeks gestation), and 2.2% congenital abnormalities. The mRNA COVID-19 vaccines are immunogenic in pregnant women and no obvious safety concerns observed. There is no increased incidence of adverse reactions in pregnant women. Our finding supports that pregnant women should receive the vaccination at their earliest convenience regardless of trimester.

The type of COVID-19 vaccination does not affect reproductive function and pregnancy outcomes in infertile couples

Introduction

Studies on the effect of vaccine type and two other vaccines other than inactivated vaccines approved in China on in vitro fertilization (IVF) pregnancy outcomes are rare. To complement and confirm the existing findings, this research aimed to investigate whether there are adverse effects of different vaccine types in females and males on reproductive function and clinical pregnancy.

Methods

This retrospective study enrolled 6,455 fresh embryo transfer cycles at the First Affiliated Hospital of Zhengzhou University between May 1, 2021, and October 31, 2022. The primary outcome is the clinical pregnancy rate (CPR). At the same time, the secondary results are the number of oocytes retrieved, two pronuclei (2PN) rate, blastocyst formation rate, high-quality blastocyst rate, and semen parameters (volume, density, sperm count, forward motility rate, total motility rate, immobility rate, and DNA fragment index (DFI) rate).

Results

In the comparison of ovarian stimulation indicators, no statistically significant differences (P > 0.05) were found in Gn days, endometrial thickness, 2PN rate, metaphase 2 (MII) rate, high-quality embryo rate, and blastocyst formation rate. No significant differences (P>0.05) were found in age, body mass index (BMI), education level, and semen parameters (volume, density, sperm count, forward motility rate, total motility rate, immobility rate, and DFI rate) in these four groups. The multivariate regression model showed that neither the types of vaccines nor the vaccination status of both infertile couples significantly affected clinical pregnancy.

Discussion

The type of vaccine does not appear to have an unfavorable effect on ovarian stimulation, embryo development, semen parameters, and clinical pregnancy.

Effectiveness and safety of COVID-19 vaccines on maternal and perinatal outcomes: a systematic review and meta-analysis

OBJECTIVE

To assess the effects of COVID-19 vaccines in women before or during pregnancy on SARS-CoV-2 infection-related, pregnancy, offspring and reactogenicity outcomes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Major databases between December 2019 and January 2023.

STUDY SELECTION

Nine pairs of reviewers contributed to study selection. We included test-negative designs, comparative cohorts and randomised trials on effects of COVID-19 vaccines on infection-related and pregnancy outcomes. Non-comparative cohort studies reporting reactogenicity outcomes were also included.

QUALITY ASSESSMENT, DATA EXTRACTION AND ANALYSIS

Two reviewers independently assessed study quality and extracted data. We undertook random-effects meta-analysis and reported findings as HRs, risk ratios (RRs), ORs or rates with 95% CIs.

RESULTS

Sixty-seven studies (1 813 947 women) were included. Overall, in test-negative design studies, pregnant women fully vaccinated with any COVID-19 vaccine had 61% reduced odds of SARS-CoV-2 infection during pregnancy (OR 0.39, 95% CI 0.21 to 0.75; 4 studies, 23 927 women; I2=87.2%) and 94% reduced odds of hospital admission (OR 0.06, 95% CI 0.01 to 0.71; 2 studies, 868 women; I2=92%). In adjusted cohort studies, the risk of hypertensive disorders in pregnancy was reduced by 12% (RR 0.88, 95% CI 0.82 to 0.92; 2 studies; 115 085 women), while caesarean section was reduced by 9% (OR 0.91, 95% CI 0.85 to 0.98; 6 studies; 30 192 women). We observed an 8% reduction in the risk of neonatal intensive care unit admission (RR 0.92, 95% CI 0.87 to 0.97; 2 studies; 54 569 women) in babies born to vaccinated versus not vaccinated women. In general, vaccination during pregnancy was not associated with increased risk of adverse pregnancy or perinatal outcomes. Pain at the injection site was the most common side effect reported (77%, 95% CI 52% to 94%; 11 studies; 27 195 women).

CONCLUSION

COVID-19 vaccines are effective in preventing SARS-CoV-2 infection and related complications in pregnant women.

PROSPERO REGISTRATION NUMBER

CRD42020178076.

Effects of SARS-Cov-2 mRNA vaccine on placental histopathology: Comparison of a population of uncomplicated COVID-19 positive pregnant women

1.

INTRODUCTION

This study investigates the impact of SARS-CoV-2 infection on placental histopathology in pregnant women, comparing outcomes between vaccinated and non-vaccinated individuals. Despite known adverse pregnancy outcomes linked to SARS-CoV-2 infection, the specific effects on the placenta remain unclear. Although vaccination has demonstrated a substantial reduction in infection severity, its impact on placental health requires more insight. 2.

METHODS

Between March 2021 and July 2022, 387 COVID-19-positive women were admitted for delivery. Of these, 98 with non-severe symptoms were analyzed: 35 vaccinated during pregnancy, and 63 non-vaccinated. Two independent pathologists evaluated all placental specimens. 3.

RESULTS

The only differing obstetrical characteristic between groups was the mode of delivery (p 0.047), lacking clinical implications. Over 85% of placentas exhibited microscopic abnormalities, predominantly maternal vascular supply disorders (vaccinated 89.1%; unvaccinated 85.5%). Comparing vaccinated and unvaccinated groups revealed statistically significant differences, notably in increased focal perivillous fibrin deposits (IFPFD) [17.1% vs. 33.3% (p 0.04)] and avascular fibrotic villi (AFV) [0% vs. 11.1% (p 0.04)]. Binomial logistic regression confirmed the vaccine's protective role against IFPFD (aOR 0.36; 95%CI 013-0.99) and AVF (aOR 0.06, 95% CI 0.003-0.98). A sub-analysis in vaccinated women showed a positive correlation between the timing of the first dose and IFPFD presence (p 0.018). 4.

DISCUSSION

The lower incidence of maternal and fetal vascular malperfusion placental features in vaccinated women, coupled with the timing correlation, supports the vaccine's protective effect on placental tissue in COVID-19-infected pregnant patients. Notably, no side effects were reported post-vaccination, emphasizing the vaccine's safety and advocating for its secure administration in pregnant populations.

SARS-CoV-2-Placental effects and association with stillbirth

SARS-CoV-2 has had a significant impact on pregnancy outcomes due to the effects of the virus and the altered healthcare environment. Stillbirth has been relatively hidden during the COVID-19 pandemic, but a clear link between SARS-CoV-2 and poor fetal outcome emerged in the Alpha and Delta waves. A small minority of women/birthing people who contracted COVID-19 developed SARS-CoV-2 placentitis. In many reported cases this was linked to intrauterine fetal death, although there are cases of delivery just before imminent fetal demise and we shall discuss how some cases are sub-clinical. What is surprising, is that SARS-CoV-2 placentitis is often not associated with severe maternal COVID-19 infection and this makes it difficult to predict. The worst outcomes seem to be with diffuse placental disease which occurs within 21 days of COVID-19 diagnosis. Poor outcomes are often pre-dated by reduced fetal movements but are not associated with ultrasound changes. In some cases, there has also been maternal thrombocytopenia, or coagulation abnormalities, which may provide a clue as to which pregnancies are at risk of fetal demise if a further variant of concern is to emerge. In future, multidisciplinary collaboration and cross-boundary working must be prioritised, to identify quickly such a phenomenon and provide clinicians with clear guidance for reducing fetal death and associated poor outcomes. While we wait to see if COVID-19 brings a future variant of concern, we must focus on appropriate future management of women who have had SARS-CoV-2 placentitis. As a placental condition with an infectious aetiology, SARS-CoV-placentitis is unlikely to recur in a subsequent pregnancy and thus a measured approach to subsequent pregnancy management is needed.

Minimal mRNA uptake and inflammatory response to COVID-19 mRNA vaccine exposure in human placental explants

Despite universal recommendations for COVID-19 mRNA vaccination in pregnancy, uptake has been lower than desired. There have been limited studies of the direct impact of COVID-19 mRNA vaccine exposure in human placental tissue. Using a primary human placental explants model, we investigated the uptake of two common mRNA vaccines (BNT162b2 Pfizer-BioNTech or mRNA-1273 Moderna), and whether exposure altered villous cytokine responses. Explants derived from second or third trimester chorionic villi were incubated with vaccines at supraphysiologic concentrations and analyzed at two time points. We observed minimal uptake of mRNA vaccines in placental explants by in situ hybridization and quantitative RT-PCR. No specific or global cytokine response was elicited by either of the mRNA vaccines in multiplexed immunoassays. Our results suggest that the human placenta does not readily absorb the COVID-19 mRNA vaccines nor generate a significant inflammatory response after exposure.

Impact of Obesity and Diabetes in Pregnant Women on Their Immunity and Vaccination

Pregnant women with obesity and diabetes are at increased risk of developing infections and other complications during pregnancy. Several mechanisms are involved in the immunological mechanisms that contribute to reduced immunity in these populations. Both obesity and diabetes are associated with chronic low-grade inflammation that can lead to an overactive immune response. Pregnant women with obesity and diabetes often have an increase in pro-inflammatory cytokines and adipokines, such as TNF-α, IL-6, IL-1β, leptin, and resistin, which are involved in the inflammatory response. Insulin resistance can also affect the functioning of immune cells. Furthermore, both conditions alter the composition of the gut microbiome, which produces a variety of biomolecules, including short-chain fatty acids, lipopolysaccharides, and other metabolites. These substances may contribute to immune dysfunction. In addition to increasing the risk of infections, obesity and diabetes can also affect the efficacy of vaccinations in pregnant women. Pregnant women with obesity and diabetes are at increased risk of developing severe illness and complications from COVID-19, but COVID-19 vaccination may help protect them and their fetuses from infection and its associated risks. Since both obesity and diabetes classify a pregnancy as high risk, it is important to elucidate the impact of these diseases on immunity and vaccination during pregnancy. Research examining the efficacy of the COVID-19 vaccine in a high-risk pregnant population should be of particular value to obstetricians whose patients are hesitant to vaccinate during pregnancy. Further research is needed to better understand these mechanisms and to develop effective interventions to improve immune function in these populations.

Maternal and neonatal outcomes of COVID-19 vaccination during pregnancy, a systematic review and meta-analysis

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is associated with increased pregnancy complications. Despite effective vaccination strategies for the general population, the evidence on the safety and efficacy of Coronavirus disease 2019 (COVID-19) vaccinations in pregnancy is limited due to a lack of well-powered studies. The present study compares the maternal, neonatal, and immunological outcomes between vaccinated pregnant and unvaccinated pregnant women using a systematic review and meta-analysis approach. We included 37 studies with a total of 141,107 pregnant women (36.8% vaccinated) spread across all outcomes. Our evidence indicates a higher rate of cesarean section in the 1898 vaccinated pregnant women compared to the 6180 women who did not receive vaccination (OR = 1.20, CI = (1.05, 1.38), P = 0.007, I2 = 45%). Regarding immunological outcomes, the risk of SARS-CoV-2 infection during pregnancy or postpartum was significantly reduced in 6820 vaccinated pregnant women compared to 17,010 unvaccinated pregnant women (OR = 0.25, CI = 0.13-0.48, P < 0.0001, I2 = 61%), as evident from qualitative assessment indicating significantly higher postpartum antibody titers compared to that observed in both unvaccinated mothers and mothers who have recently recovered from a SARS-CoV-2 infection. Our analysis represents high quality evidence showing that COVID-19 vaccination effectively raises antibody titers against SARS-CoV-2. This may confer protection against infection during pregnancy and the postpartum period. In addition to being protective against SARS-CoV-2, the vaccine was associated with decreased odds of preterm delivery. Furthermore, COVID-19 vaccination may also be associated with higher odds of cesarean section.

Effect of SARS-CoV-2 Infection and COVID-19 Vaccination on Oxidative Status of Human Placenta: A Preliminary Study

Infection with SARS-CoV-2 during pregnancy increases the risk of pregnancy complications associated with inflammation, which could lead to oxidative stress in the placenta. Whether vaccination against COVID-19 has any effect is unclear. This study aimed to analyze the effects of SARS-CoV-2 infection and vaccination against COVID-19 during pregnancy on oxidative stress in the placenta and on extracellular DNA (ecDNA) in umbilical cord plasma. Placenta samples from healthy uninfected and unvaccinated control patients who recovered from COVID-19 and women vaccinated against COVID-19 during pregnancy were collected. Biomarkers of oxidative damage and antioxidant capacity were assessed in the placenta homogenates. EcDNA and deoxyribonuclease activity were quantified in umbilical cord plasma using real-time PCR and the single radial enzyme diffusion method, respectively. Markers of oxidative damage to lipids and proteins as well as antioxidant capacity in the placenta did not differ between the study groups. No differences were observed in total, nuclear or mitochondrial ecDNA, or deoxyribonuclease activity in the umbilical cord plasma. Taking into account the limits of a small observational study, our results suggest that the infection with SARS-CoV-2 and vaccination against COVID-19 do not induce any major disturbances in the balance between the production of free radicals and antioxidant activity in the placenta. This is in line with the minor effects on fetal outcomes and ecDNA as a suggested marker of fetal well-being.

Strategies to Address COVID-19 Vaccine and Pregnancy Myths

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses risks to pregnant women and their infants. The spread of misinformation about COVID-19 vaccination is a barrier to optimizing vaccination rates among women of childbearing age. We conducted an environmental scan to identify misinformation about COVID-19 vaccination, pregnancy, and fertility, and a review to identify evidence to refute misinformation and strategies to correct and prevent the spread of misinformation. Seven identified themes of misinformation are: the vaccine causes female infertility; can cause miscarriage; and can decrease male fertility; mRNA vaccines attack the placenta; pregnant and breastfeeding persons should not get the vaccine; the vaccine can change menstrual cycles; and vaccinated people can spread infertility symptoms to unvaccinated people. Strategies that can be implemented by social media platforms to help prevent misinformation spread and correct existing health misinformation include improving information regulation by modifying community standards, implementing surveillance algorithms, and applying warning labels to potentially misleading posts. Health services organizations and clinicians can implement health misinformation policies, directly recommend vaccinations, provide credible explanations and resources to debunk misinformation, educate patients and populations on spotting misinformation, and apply effective communication strategies. More research is needed to assess longer-term effects of vaccination among women of childbearing age to strengthen the defense against misinformation and to evaluate strategies that aim to prevent and correct misinformation spread about COVID-19 vaccinations.

Analysis of placental pathology after COVID-19 by timing and severity of infection

BACKGROUND

COVID-19 during pregnancy can have serious effects on pregnancy outcomes. The placenta acts as an infection barrier to the fetus and may mediate adverse outcomes. Increased frequency of maternal vascular malperfusion has been detected in the placentas of patients with COVID-19 compared with controls, but little is known about how the timing and severity of infection affect placental pathology.

OBJECTIVE

This study aimed to examine the effects of SARS-CoV-2 infection on placental pathology, specifically whether the timing and severity of COVID-19 affect pathologic findings and associations with perinatal outcomes.

STUDY DESIGN

This was a descriptive retrospective cohort study of pregnant people diagnosed with COVID-19 who delivered between April 2020 and September 2021 at 3 university hospitals. Demographic, placental, delivery, and neonatal outcomes were collected through medical record review. The timing of SARS-CoV-2 infection was noted, and the severity of COVID-19 was categorized on the basis of the National Institutes of Health guidelines. The placentas of all patients with positive nasopharyngeal reverse transcription-polymerase chain reaction COVID-19 testing were sent for gross and microscopic histopathologic examinations at the time of delivery. Nonblinded pathologists categorized histopathologic lesions according to the Amsterdam criteria. Univariate linear regression and chi-square analyses were used to assess how the timing and severity of SARS-CoV-2 infection affected placental pathologic findings.

RESULTS

This study included 131 pregnant patients and 138 placentas, with most patients delivered at the University of California, Los Angeles (n=65), followed by the University of California, San Francisco (n=38) and Zuckerberg San Francisco General Hospital (n=28). Most patients were diagnosed with COVID-19 in the third trimester of pregnancy (69%), and most infections were mild (60%). There was no specific placental pathologic feature based on the timing or severity of COVID-19. There was a higher frequency of placental features associated with response to infection in the placentas from infections before 20 weeks of gestation than that from infections after 20 weeks of gestation (P=.001). There was no difference in maternal vascular malperfusion by the timing of infection; however, features of severe maternal vascular malperfusion were only found in the placentas of patients with SARS-CoV-2 infection in the second and third trimesters of pregnancy, not in the placentas of patients with COVID-19 in the first trimester of pregnancy.

CONCLUSION

Placentas from patients with COVID-19 showed no specific pathologic feature, regardless of the timing or severity of the disease. There was a higher proportion of placentas from patients with COVID-19-positive tests in earlier gestations with evidence of placental infection-associated features. Future studies should focus on understanding how these placental features in SARS-CoV-2 infections go on to affect pregnancy outcomes.

The risk of miscarriage following COVID-19 vaccination: a systematic review and meta-analysis

STUDY QUESTION

What is the risk of miscarriage among pregnant women who received any of the COVID-19 vaccines?

SUMMARY ANSWER

There is no evidence that COVID-19 vaccines are associated with an increased risk of miscarriage.

WHAT IS KNOWN ALREADY

In response to the COVID-19 pandemic, the mass roll-out of vaccines helped to boost herd immunity and reduced hospital admissions, morbidity, and mortality. Still, many were concerned about the safety of vaccines for pregnancy, which may have limited their uptake among pregnant women and those planning a pregnancy.

STUDY DESIGN, SIZE, DURATION

For this systematic review and meta-analysis, we searched MEDLINE, EMBASE, and Cochrane CENTRAL from inception until June 2022 using a combination of keywords and MeSH terms.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We included observational and interventional studies that enrolled pregnant women and evaluated any of the available COVID-19 vaccines compared to placebo or no vaccination. We primarily reported on miscarriage in addition to ongoing pregnancy and/or live birth.

MAIN RESULTS AND THE ROLE OF CHANCE

We included data from 21 studies (5 randomized trials and 16 observational studies) reporting on 149 685 women. The pooled rate of miscarriage among women who received a COVID-19 vaccine was 9% (n = 14 749/123 185, 95% CI 0.05-0.14). Compared to those who received a placebo or no vaccination, women who received a COVID-19 vaccine did not have a higher risk of miscarriage (risk ratio (RR) 1.07, 95% CI 0.89-1.28, I2 35.8%) and had comparable rates for ongoing pregnancy or live birth (RR 1.00, 95% CI 0.97-1.03, I2 10.72%).

LIMITATIONS, REASONS FOR CAUTION

Our analysis was limited to observational evidence with varied reporting, high heterogeneity and risk of bias across included studies, which may limit the generalizability and confidence in our findings.

WIDER IMPLICATIONS OF THE FINDINGS

COVID-19 vaccines are not associated with an increase in the risk of miscarriage or reduced rates of ongoing pregnancy or live birth among women of reproductive age. The current evidence remains limited and larger population studies are needed to further evaluate the effectiveness and safety of COVID-19 vaccination in pregnancy.

STUDY FUNDING/COMPETING INTEREST(S)

No direct funding was provided to support this work. M.P.R. was funded by the Medical Research Council Centre for Reproductive Health Grant No: MR/N022556/1. B.H.A.W. hold a personal development award from the National Institute of Health Research in the UK. All authors declare no conflict of interest.

REGISTRATION NUMBER

CRD42021289098.

Effects of COVID-19 vaccination during pregnancy on SARS-CoV-2 infection and maternal and neonatal outcomes: A systematic review and meta-analysis

SARS-CoV-2 infection during pregnancy is associated with adverse maternal and neonatal outcomes, but no systematic synthesis of evidence on COVID-19 vaccination during pregnancy against these outcomes has been undertaken. Thus, we aimed to assess the collective evidence on the effects of COVID-19 vaccination during pregnancy on maternal and neonatal outcomes. PubMed/MEDLINE, CENTRAL, and EMBASE were systematically searched for articles published up to 1 November 2022. A systematic review and meta-analysis were performed to calculate pooled effects size and 95% confidence interval (CI). We evaluated 30 studies involving 862,272 individuals (308,428 vaccinated and 553,844 unvaccinated). Overall pooled analyses in pregnant women during pregnancy showed reduced risks of SARS-CoV-2 infection by 60% (41%-73%), COVID-19 hospitalisation during pregnancy by 53% (31%-69%), and COVID-19 intensive care unit (ICU) admission by 82% (12%-99%). Neonates of vaccinated women were 1.78 folds more likely to acquire SARS-CoV-2 infection during the first 2, 4 and 6 months of life during the Omicron period. The risk of stillbirth was reduced by 45% (17%-63%) in association with vaccination (vs. no vaccination) in pregnancy. A decrease of 15% (3%-25%), 33% (14%-48%), and 33% (17%-46%) in the odds of preterm births before 37, 32 and 28 weeks' gestation were associated with vaccination (vs. no vaccination) in pregnancy, respectively. The risk of neonatal ICU admission was significantly lower by 20% following COVID-19 vaccination in pregnancy (16%-24%). There was no evidence of a higher risk of adverse outcomes including miscarriage, gestational diabetes, gestational hypertension, cardiac problems, oligohydramnios, polyhydramnios, unassisted vaginal delivery, cesarean delivery, postpartum haemorrhage, gestational age at delivery, placental abruption, Apgar score at 5 min below 7, low birthweight (<2500 g), very low birthweight (<1500 g), small for gestational age, and neonatal foetal abnormalities. COVID-19 vaccination during pregnancy is safe and highly effective in preventing maternal SARS-CoV-2 infection in pregnancy, without increasing the risk of adverse maternal and neonatal outcomes, and is associated with a reduction in stillbirth, preterm births, and neonatal ICU admission. Importantly, maternal vaccination did not reduce the risk of neonatal SARS-CoV-2 infection during the first 6 months of life during the Omicron period.

Vaccination options for pregnant women during the Omicron period

Omicron exhibits reduced pathogenicity in general population than the previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. However, the severity of disease and pregnancy outcomes of Omicron infection among pregnant women have not yet been definitively established. Meanwhile, substantial proportions of this population have doubts about the necessity of vaccination given the reports of declining efficacy of coronavirus disease 2019 (COVID-19) vaccines. Herein, we comprehensively discuss the clinical outcomes of infected pregnant women during the Omicron period and summarize the available data on the safety and efficacy profile of COVID-19 vaccination. The results found that the incidence of moderate and severe disease, maternal mortality, pregnancy loss, preterm delivery, stillbirth, preeclampsia/eclampsia, and gestational hypertension during the Omicron period are similar to those during the Pre-Delta period. In view of the effects of mass vaccination and previous natural infection on disease severity, the virulence of Omicron in pregnant women may be comparable to or even higher than that of the Pre-Delta variant. Moreover, the currently approved COVID-19 vaccines are safe and effective for pregnant women. Particularly, those who received a second or third dose had significantly less severe disease with little progression to critical illness or death compared with those who were unvaccinated or received only one dose. Therefore, in the case of the rapid spread of Omicron, pregnant women should still strictly follow preventive measures to avoid infection and receive the COVID-19 vaccine in a timely manner.

SARS-CoV-2 placentitis, stillbirth, and maternal COVID-19 vaccination: clinical-pathologic correlations

Stillbirth is a recognized complication of COVID-19 in pregnant women that has recently been demonstrated to be caused by SARS-CoV-2 infection of the placenta. Multiple global studies have found that the placental pathology present in cases of stillbirth consists of a combination of concurrent destructive findings that include increased fibrin deposition that typically reaches the level of massive perivillous fibrin deposition, chronic histiocytic intervillositis, and trophoblast necrosis. These 3 pathologic lesions, collectively termed SARS-CoV-2 placentitis, can cause severe and diffuse placental parenchymal destruction that can affect >75% of the placenta, effectively rendering it incapable of performing its function of oxygenating the fetus and leading to stillbirth and neonatal death via malperfusion and placental insufficiency. Placental infection and destruction can occur in the absence of demonstrable fetal infection. Development of SARS-CoV-2 placentitis is a complex process that may have both an infectious and immunologic basis. An important observation is that in all reported cases of SARS-CoV-2 placentitis causing stillbirth and neonatal death, the mothers were unvaccinated. SARS-CoV-2 placentitis is likely the result of an episode of SARS-CoV-2 viremia at some time during the pregnancy. This article discusses clinical and pathologic aspects of the relationship between maternal COVID-19 vaccination, SARS-CoV-2 placentitis, and perinatal death.

Minimal mRNA uptake and inflammatory response to COVID-19 mRNA vaccine exposure in human placental explants

Despite universal recommendations for COVID-19 mRNA vaccination in pregnancy, uptake has been lower than desired. There have been limited studies of the direct impact of COVID-19 mRNA vaccine exposure in human placental tissue. Using a primary human villous explant model, we investigated the uptake of two common mRNA vaccines (BNT162b2 Pfizer-BioNTech or mRNA-1273 Moderna), and whether exposure altered villous cytokine responses. Explants derived from second or third trimester chorionic villi were incubated with vaccines at supraphysiologic concentrations and analyzed at two time points. We observed minimal uptake of mRNA vaccines in placental explants by in situ hybridization and quantitative RT-PCR. No specific or global cytokine response was elicited by either of the mRNA vaccines in multiplexed immunoassays. Our results suggest that the human placenta does not readily absorb the COVID-19 mRNA vaccines nor generate a significant inflammatory response after exposure.

Associations of COVID-19 vaccination during pregnancy with adverse neonatal and maternal outcomes: A systematic review and meta-analysis

Objectives

The low COVID-19 vaccine uptake rate among pregnant women is mainly due to safety concerns about COVID-19 vaccines due to limited safety evidence. Our goal was to evaluate the safety of COVID-19 vaccination during pregnancy with up-to-date evidence.

Methods

A comprehensive search of MEDLINE, EMBASE, the Cochrane Library, and clinicaltrials.gov was performed on April 5th, 2022, and updated on May 25th, 2022. Studies evaluating the association of COVID-19 vaccination during pregnancy with adverse maternal and neonatal outcomes were included. Two reviewers independently performed the risk of bias assessment and data extraction. Inverse variance random effect meta-analyses were performed to pool outcome data.

Results

Forty-three observational studies were included. COVID-19 vaccination [96,384 (73.9%) BNT162b2, 30,889 (23.7%) mRNA-1273, and 3,172 (2.4%) other types] during pregnancy [23,721 (18.3%) in the first trimester, 52,778 (40.5%) in the second trimester, and 53,886 (41.2%) in the third trimester].was associated with reduced risks of stillbirth or neonatal death (OR, 0.74; 95% CI, 0.60-0.92). Sensitivity analysis restricted to studies in participants without COVID-19 showed that the pooled effect was not robust. COVID-19 vaccination during pregnancy was not associated with congenital anomalies (OR, 0.83; 95% CI, 0.63-1.08), preterm birth (OR, 0.98; 95% CI, 0.90-1.06), NICU admission or hospitalization (OR, 0.94; 95% CI, 0.84-1.04), an Apgar score at 5 min <7 (OR, 0.93; 95% CI, 0.86-1.01), low birth weight (OR, 1.00; 95% CI, 0.88-1.14), miscarriage (OR, 0.99; 95% CI, 0.88-1.11), cesarean delivery (OR, 1.07; 95% CI, 0.96-1.19), or postpartum hemorrhage (OR, 0.91; 95% CI, 0.81-1.01).

Conclusions

COVID-19 vaccination during pregnancy was not associated with any of the adverse neonatal or maternal outcomes studied. Interpretation of study findings is limited by the types and timing of vaccination. The vaccinations in our study received during pregnancy were primarily mRNA vaccines administered in the second and third trimester. Future RCTs and meta-analysis are warranted to evaluate the efficacy and long-term effects of the COVID-19 vaccines.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022322525, identifier: PROSPERO, CRD42022322525.

Effectiveness and safety of COVID-19 vaccine in pregnant women: A systematic review with meta-analysis

BACKGROUND

There are limited data regarding COVID-19 vaccination during pregnancy.

OBJECTIVES

To evaluate the effects of COVID-19 vaccination received during pregnancy on SARS-CoV-2 infection, COVID-19-related hospitalisation, COVID-19-related intensive care unit (ICU) admission and maternal-fetal complications.

SEARCH STRATEGY

MEDLINE, CINHAL, Embase, Scopus and CENTRAL databases, as well as ClinicalTrials.gov, reference lists, related articles and grey literature sources.

SELECTION CRITERIA

Randomised controlled trials, non-randomised studies of interventions, pregnant women, COVID-19 vaccination during pregnancy.

DATA COLLECTION AND ANALYSIS

Study selection, risk-of-bias assessment, data extraction and assessment of the certainty of evidence using the GRADE method were performed independently by two authors. Meta-analyses were performed using Cochrane RevMan 5.4. PROSPERO registration number: CRD42022308849.

MAIN RESULTS

We included 14 observational studies (362 353 women). The administration of a COVID-19 vaccine during pregnancy resulted in a statistically significant reduction in SARS-CoV-2 infection (OR 0.46, 95% CI 0.28-0.76) and COVID-19-related hospitalisation (OR 0.41, 95% CI 0.33-0.51). The effect appeared to be greater in fully vaccinated women, for both infection (OR 0.31, 95% CI 0.16-0.59) and hospitalisation (OR 0.15, 95% CI 0.10-0.21). However, the certainty of evidence was very low. The difference in COVID-19-related ICU admission between vaccinated and unvaccinated individuals did not reach statistical significance (OR 0.58, 95% CI 0.13-2.58). Finally, there were no statistically significant differences in any of the maternal-fetal complications considered in the included studies.

CONCLUSIONS

COVID-19 vaccination administered during pregnancy seems to reduce SARS-CoV-2 infection and COVID-19-related hospitalisation, with no significant effects on maternal-fetal complications.

COVID-19 vaccine and pregnancy outcomes: A systematic review and meta-analysis

OBJECTIVES

To explore perinatal outcomes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-vaccinated pregnant women compared with unvaccinated counterparts.

METHODS

Search was conducted using Web of Science, Scopus, ClinicalTrial.gov, MEDLINE, Embase, OVID, and Cochrane Library as electronic databases. We included observational studies evaluating pregnant women undergoing SARS-CoV-2 vaccination and compared pregnancy and perinatal outcomes with those in unvaccinated women. Categorical variables were assessed using odds ratio (OR) with 95% confidence interval (CI), whereas for continuous variables, the results were expressed as mean difference with their 95% CI. All analyses were performed by adopting the random effect model of DerSimonian and Laird.

RESULTS

There was no difference in the probability of having a small-for-gestational-age fetus (OR 0.97, 95% CI 0.85-1.09; P = 0.570), but we observed a reduced probability of a non-reassuring fetal monitoring, a reduced gestational age at delivery, and a reduced probability of premature delivery in vaccinated pregnant women versus unvaccinated ones.

CONCLUSION

The probability of small for gestational age is similar between vaccinated and unvaccinated pregnant women, and the former also had a slightly reduced rate of premature delivery.

Evaluation of Safety Concerns for COVID-19 Immunization of Pregnant Women: a Systematic Review of Emerging Evidence

Objectives: There is an urgent need to review the status of COVID-19 vaccine immunization in pregnant women globally, so that adverse outcomes may be prevented. In this study, we performed a systematic review to evaluate the probable outcomes of COVID-19 vaccination in pregnant women. Materials and methods:An electronic search over three months (June 15-August 15, 2021) was conducted. Original studies evaluating safety concerns in pregnant women for COVID-19 vaccination were included. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2009 guidelines were used for data collection and reporting of findings. Results:COVID-19 vaccination in pregnant women was not associated with increased adverse effects or complications to the mother as well as the developing fetus or new-born compared to non-vaccinated pregnant women. Vaccinated pregnant women showed a robust immune response against COVID-19 infection. Conclusion:COVID-19 vaccination during pregnancy causes no significant health risks for the mother or the developing fetus or new-born.

Absence of SARS-CoV-2 Spike glycoprotein expression in placentas from individuals after mRNA SARS-CoV-2 vaccination

Current public health initiatives to contain the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) global pandemic focus on expanding vaccination efforts to include vulnerable populations such as pregnant people. Vaccines using messenger ribonucleic acid (mRNA) technology rely on translation by immune cells, primarily at the injection site. Hesitancy remains among the general population regarding the safety of mRNA vaccines during gestation, and it remains unknown whether the SARS-CoV-2 Spike protein (the product of mRNA vaccines available) accumulates in the placenta after vaccination. Objective: To determine whether Spike protein translation and accumulation occurs in placental tissue in the context of recent mRNA SARC-CoV-2 vaccination during pregnancy. We identified 48 patients receiving one or two doses of mRNA SARS-CoV-2 vaccine during gestation and used immunohistochemistry against SARS-CoV-2 Spike protein in formalin-fixed, paraffin-embedded placental tissue. One placenta, positive for SARS-CoV-2 RNA by in situ hybridization (ISH) was used as positive control. Seven term placentas collected prior to the emergence of SARS-CoV-2 served as negative controls. Eighty one percent of patients in the study group underwent third-trimester delivery; remaining had a first-trimester spontaneous abortion or elective second-trimester termination. Patients received two (52%) or one (48%) vaccine doses during pregnancy, with a median interval between latest dose and delivery of 13 days (range 2-79 days). Most (63%) cases had their latest dose within 15 days prior to delivery. All the placentas in the study and negative control groups were negative for SARS-CoV-2 immunohistochemistry. Six study cases with short vaccine-delivery intervals (2-7 days) were subjected to SARS-CoV-2 ISH and were negative. Our findings suggest that mRNA vaccines do not reach significant concentrations in the placenta given the absence of definitive SARS-CoV-2 Spike protein accumulation in placental tissue. This observation provides evidence supporting the safety of mRNA vaccines to the placental-fetal unit.

Examining Pregnant Veterans' Acceptance and Beliefs Regarding the COVID-19 Vaccine

BACKGROUND

Pregnant persons have received mixed messages regarding whether or not to receive COVID-19 vaccines as limited data are available regarding vaccine safety for pregnant and lactating persons and breastfeeding infants.

OBJECTIVE

The aims of this study were to examine pregnant Veteran's acceptance of COVID-19 vaccines, along with perceptions and beliefs regarding vaccine safety and vaccine conspiracy beliefs.

DESIGN AND PARTICIPANTS

We conducted a cross-sectional survey of pregnant Veterans enrolled in VA care who were taking part in an ongoing cohort study at 15 VA medical centers between January and May 2021.

MAIN MEASURES

Pregnant Veterans were asked whether they had been offered the COVID-19 vaccine during pregnancy, and whether they chose to accept or refuse it. Additional questions focused on perceptions of COVID-19 vaccine safety and endorsements of vaccine knowledge and conspiracy beliefs. Logistic regression was utilized to examine predictors of acceptance of a vaccine during pregnancy.

KEY RESULTS

Overall, 72 pregnant Veterans were offered a COVID-19 vaccine during pregnancy; over two-thirds (69%) opted not to receive a vaccine. Reasons for not receiving a vaccine included potential effects on the baby (64%), side effects for oneself (30%), and immunity from a past COVID-19 infection (12%). Those who received a vaccine had significantly greater vaccine knowledge and less belief in vaccine conspiracy theories. Greater knowledge of vaccines in general (aOR: 1.78; 95% CI: 1.2-2.6) and lower beliefs in vaccine conspiracies (aOR: 0.76; 95% CI: 0.6-0.9) were the strongest predictors of acceptance of a COVID-19 vaccine during pregnancy.

CONCLUSIONS

Our study provides important insights regarding pregnant Veterans' decisions to accept the COVID-19 vaccine, and reasons why they may choose not to accept the vaccine. Given the high endorsement of vaccine conspiracy beliefs, trusted healthcare providers should have ongoing, open discussions about vaccine conspiracy beliefs and provide additional information to dispel these beliefs.

Covid-19 vaccination in pregnancy

Pregnancy is an independent risk factor for severe covid-19. Vaccination is the best way to reduce the risk for SARS-CoV-2 infection and limit its morbidity and mortality. The current recommendations from the World Health Organization, Centers for Disease Control and Prevention, and professional organizations are for pregnant, postpartum, and lactating women to receive covid-19 vaccination. Pregnancy specific considerations involve potential effects of vaccination on fetal development, placental transfer of antibodies, and safety of maternal vaccination. Although pregnancy was an exclusion criterion in initial clinical trials of covid-19 vaccines, observational data have been rapidly accumulating and thus far confirm that the benefits of vaccination outweigh the potential risks. This review examines the evidence supporting the effectiveness, immunogenicity, placental transfer, side effects, and perinatal outcomes of maternal covid-19 vaccination. Additionally, it describes factors associated with vaccine hesitancy in pregnancy. Overall, studies monitoring people who have received covid-19 vaccines during pregnancy have not identified any pregnancy specific safety concerns. Additional information on non-mRNA vaccines, vaccination early in pregnancy, and longer term outcomes in infants are needed. To collect this information, vaccination during pregnancy must be prioritized in vaccine research.

Maternal and neonatal safety outcomes after SAR-CoV-2 vaccination during pregnancy: a systematic review and meta-analysis

Background and objective

More than five million individuals died because of problems connected to COVID-19. SARS-Cov-2 poses a particular challenge to expectant mothers, who comprise one of the most vulnerable segments of the population. Our aim is to demonstrate the maternal and neonatal safety of the COVID-19 vaccine during pregnancy.

Methods

We searched PubMed, Cochrane Library, Scopus, Web of Science (WOS), Embase, Ovid, MedRxiv, and BioRxiv databases from inception till December 2021 and then updated it in April 2022. Additionally, we searched ClinicalTrials.gov, Research Square and grey literature. Cohort, case–control studies, and randomized controlled trials detecting the safety of the Covid-19 vaccine during pregnancy were included. We used the Cochrane tool and Newcastle–Ottawa Scale to assess the risk of bias of the included studies and the GRADE scale to assess the quality of evidence. A meta-analysis was conducted using review manager 5.4.

Results

We included 13 studies with a total number of 56,428 patients. Our analysis showed no statistically significant difference in the following outcomes: miscarriage (1.56% vs 0.3%. RR 1.23; 95%CI 0.54 to 2.78); length of maternal hospitalization (MD 0.00; 95%CI -0.08 to 0.08); puerperal fever (1.71% vs 1.1%. RR 1.04; 95%CI 0.67 to 1.61); postpartum hemorrhage (4.27% vs 3.52%. RR 0.84; 95%CI 0.65 to 1.09); instrumental or vacuum-assisted delivery (4.16% vs 4.54%. RR 0.94; 95%CI 0.57 to 1.56); incidence of Apgar score ≤ 7 at 5 min (1.47% vs 1.48%. RR 0.86; 95%CI 0.54 to 1.37); and birthweight (MD -7.14; 95%CI -34.26 to 19.99).

Conclusion

In pregnancy, the current meta-analysis shows no effect of SAR-CoV-2 vaccination on the risk of miscarriage, length of stay in the hospital, puerperal fever, postpartum hemorrhage, birth weight, or the incidence of an Apgar score of ≤ 7 at 5 min.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04884-9.

SARS-CoV-2 infection and COVID-19 vaccination in pregnancy

SARS-CoV-2 infection poses increased risks of poor outcomes during pregnancy, including preterm birth and stillbirth. There is also developing concern over the effects of SARS-CoV-2 infection on the placenta, and these effects seem to vary between different viral variants. Despite these risks, many pregnant individuals have been reluctant to be vaccinated against the virus owing to safety concerns. We now have extensive data confirming the safety and effectiveness of COVID-19 vaccination during pregnancy, although it will also be necessary to determine the effectiveness of these vaccines specifically against newly emerging viral variants, including Omicron. In this Progress article, I cover recent developments in our understanding of the risks of SARS-CoV-2 infection in pregnancy, and how vaccination can reduce these.

COVID-19 vaccines: Considering sex differences in efficacy and safety

The development of SARS-CoV-2 vaccines represents a significant breakthrough for managing the COVID-19 pandemic. However, their approval process has exposed a crucial limitation in clinical trial reports-that is, a disregard for sex differences in response to vaccines. Historically, males and females have shown different reactions to vaccines of many kinds, which have become apparent with the arrival of COVID-19 vaccines in late-2020. In this article, we review regulatory data from Phase III vaccine trials as well as peer-reviewed reports from vaccines administered to the general population, many of which failed to stratify results by sex. We also discuss the exclusion of pregnant and lactating persons in drug development and the regulatory guidelines for use of COVID-19 vaccines in such populations. We conclude by proposing some questions to stimulate discussion with the intent of advancing the field toward precision medicine.

SARS-CoV-2 Vaccines during Pregnancy and Breastfeeding: A Systematic Review of Maternal and Neonatal Outcomes

(1) Objective: This systematic review summarizes current knowledges about maternal and neonatal outcomes following COVID-19 vaccination during pregnancy and breastfeeding. (2) Study design: PubMed, Cochrane Library, and the Education Resources Information Center (ERIC) were searched up to 27 October 2021. The primary outcome was to estimate how many pregnant and lactating women were reported to be vaccinated and had available maternal and neonatal outcomes. (3) Results: Forty-five studies sourcing data of 74,908 pregnant women and 5098 lactating women who received COVID-19 vaccination were considered as eligible. No major side-effects were reported, especially during the second and third trimester of pregnancy and during breastfeeding. Conversely, available studies revealed that infants received specific SARS-CoV-2 antibodies after maternal vaccination. (4) Conclusions: Vaccination against the SARS-CoV-2 virus should be recommended for pregnant women, after the pros and cons have been adequately explained. In particular, given the still limited evidence and considering that fever during the first months of gestation increases the possibility of congenital anomalies, they should be carefully counseled. The same considerations apply to breastfeeding women, also considering the immune responses that mRNA vaccines can generate in their human milk.

Systematic review of the safety, immunogenicity, and effectiveness of COVID-19 vaccines in pregnant and lactating individuals and their infants

BACKGROUND

There is significant risk of complications and vulnerability to severe COVID-19 disease in pregnancy, yet hesitancy exists around COVID-19 vaccination during pregnancy and lactation.

OBJECTIVE

To summarize the safety, immunogenicity, and effectiveness of COVID-19 vaccines in pregnancy and lactation.

SEARCH STRATEGY

A systematic search of MEDLINE, Embase, PubMed, medRxiv, and bioRxiv.

SELECTION CRITERIA

Identified original studies published on pregnant and/or lactating individuals who received one or more doses of a COVID-19 vaccine.

DATA COLLECTION AND ANALYSIS

A descriptive summary organized by safety, immunogenicity, and effectiveness outcomes of COVID-19 vaccination in pregnancy and lactation.

MAIN RESULTS

In total, 23 studies were identified. Humoral response and functional immunity were interrogated and found. Increasing placental transfer ratios in cord blood were associated with increasing time from the first vaccine dose to delivery. Safety data indicated that pregnant and lactating populations experienced vaccine-related reactions at similar rates to the general population. No increased risk of adverse obstetrical or neonatal outcomes were reported. One study demonstrated that pregnant individuals were less likely to experience COVID-19 when vaccinated.

CONCLUSION

COVID-19 vaccination in pregnant and lactating individuals is immunogenic, does not cause significant vaccine-related adverse events or obstetrical and neonatal outcomes, and is effective in preventing COVID-19 disease.

Obstetric Outpatient Management During the COVID-19 Pandemic: Prevention, Treatment of Mild Disease, and Vaccination

The majority of patients with coronavirus disease 2019 will have mild or asymptomatic disease, however, obstetric patients are uniquely at risk for disease progression and adverse outcomes. Preventive strategies including masking, physical distancing, vaccination, and chemoprophylaxis have been well studied, are critical to disease mitigation, and can be used in the pregnant population. High-quality data are needed to assess safety and effectiveness of therapeutics and vaccination in pregnancy, as well as long-term data on maternal and newborn outcomes.

mRNA Covid-19 vaccines in pregnancy: A systematic review

OBJECTIVE

Pregnancy is a known risk factor for severe Coronavirus disease 2019. It is important to develop safe vaccines that elicit strong maternal and fetal antibody responses.

METHODS

Registries (ClinicalTrials.gov, the WHO Clinical Trial Registry, and the European Union Clinical Trial Registry) and databases (MEDLINE, ScienceDirect, Cochrane Library, Proquest, Springer, medRxiv, and bioRxiv) were systematically searched in June 20-22, 2021, for research articles pertaining to Covid-19 and pregnancy. Manual searches of bioRxiv and medRxiv were also conducted. Inclusion criteria were studies that focused on Covid-19 vaccination among pregnant women, while review articles and non-human studies were excluded. Infection rate, maternal antibody response, transplacental antibody transfer, and adverse events were described.

RESULTS

There were 13 observational studies with a total of 48,039 pregnant women who received mRNA vaccines. Of those, three studies investigated infection rate, six studies investigated maternal antibody response, seven studies investigated antibody transfer, three studies reported local adverse events, and five studies reported systemic adverse events. The available data suggested that the mRNA-based vaccines (Pfizer-BioNTech and Moderna) can prevent future SARS-CoV-2 infection. These vaccines did not show clear harm in pregnancy. The most commonly encountered adverse reactions were pain at the injection site, fatigue, and headache, but these were transient. Antibody responses were rapid after the first vaccine dose. After the booster, antibody responses were stronger and associated with better transplacental antibody transfer. Longer intervals between first vaccination dose and delivery were also associated with higher antibody fetal IgG and a better antibody transfer ratio.

CONCLUSIONS

The SARS-CoV-2 mRNA vaccines are encouraged for pregnancy. These vaccines can be a safe option for pregnant women and their fetuses. Two vaccine doses are recommended for more robust maternal and fetal antibody responses. Longer latency is associated with higher fetal antibody responses. Further research about its long-term effect on pregnancy is needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021261684).

Scientific Evidence Supporting Coronavirus Disease 2019 (COVID-19) Vaccine Efficacy and Safety in People Planning to Conceive or Who Are Pregnant or Lactating

Three coronavirus disease 2019 (COVID-19) vaccines have been authorized for use in the United States; specifically, the Pfizer-BioNTech, Moderna, and Johnson & Johnson-Janssen COVID-19 vaccines were granted emergency use authorization by the U.S. Food and Drug Administration in late 2020 and early 2021. Vaccination coverage and intent among adults are lowest among those aged 18-39 years and among females in particular. In females of reproductive age, enthusiasm for receiving a COVID-19 vaccine may be negatively affected by claims currently circulating widely on diverse social media platforms regarding the vaccines adversely affecting fertility and pregnancy. Yet it is important to note that these claims are anecdotal in nature and not supported by the available scientific evidence. It is also imperative that the effects of COVID-19 vaccine on reproductive health are clarified. Herein, we discuss the existing scientific data supporting COVID-19 vaccine safety and efficacy in people who are planning to conceive or who are pregnant or lactating and highlight the importance of COVID-19 vaccination in females of reproductive age.

Covid-19 vaccine and its consequences in pregnancy: Brief review

Pregnancy is linked to a higher incidence of severe Covid-19. It's critical to find safe vaccinations that elicit protective pregnant and fetal immune responses. This review summarises the rate of COVID-19 infection, maternal antibodies responsiveness, placenta antibody transmission, and adverse events after COVID-19 vaccination in pregnancy studied in epidemiological studies evaluating mRNA vaccines. Potential COVID-19 infection in pregnant women can be prevented using mRNA-based vaccinations. Gestation, childbirth, and perinatal mortality were proven unaffected by COVID-19 vaccination. Injection-site discomfort, tiredness, and migraine are the most prevalent side effects, but these are temporary. After the first dosage of vaccinations, fast antibody responses were demonstrated. The adaptive immunity is found to be more significant after booster vaccination, and is linked to improved placental antigen transmission. Two vaccination doses are associated with more robust maternal and fetal antibody levels. Longer delays between the first immunization dosage and birth are linked to greater fetal IgG antibody levels with reduction in antigen transmission proportion. The mRNA vacciness are effective in reducing the severity of COVID-19 infection and these vaccinations are regarded to be safe options for pregnant women and their unborn fetus.

Validating Claims-Based Algorithms Determining Pregnancy Outcomes and Gestational Age Using a Linked Claims-Electronic Medical Record Database

INTRODUCTION

Pregnancy outcome identification and precise estimates of gestational age (GA) are critical in drug safety studies of pregnant women. Validated pregnancy outcome algorithms based on the International Classification of Diseases, Tenth Revision, Clinical Modification/Procedure Coding System (ICD-10-CM/PCS) have not previously been published.

METHODS

We developed algorithms to classify pregnancy outcomes and estimate GA using ICD-10-CM/PCS and service codes on claims in the 2016-2018 IBM® MarketScan® Explorys® Claims-EMR Data Set and compared the results with ob-gyn adjudication of electronic medical records (EMRs). Obstetric services were grouped into episodes using hierarchical and spacing requirements. GA was based on evidence with the highest clinical accuracy. Among pregnancies with obstetric EMRs, 100 full-term live births (FTBs), 100 preterm live births (PTBs), 100 spontaneous abortions (SAs), and 24 stillbirths were selected for review. Physicians adjudicated cases using Global Alignment of Immunization safety Assessment in pregnancy (GAIA) definitions applied to structured EMRs.

RESULTS

The claims-based algorithms identified 34,204 pregnancies, of which 9.9% had obstetric EMRs. Of sampled pregnancies, 92 FTBs, 93 PTBs, 75 SAs, and 24 stillbirths were adjudicated. Among these pregnancies, the percent agreement was 97.8%, 62.4%, 100.0%, and 70.8% for FTBs, PTBs, SAs, and stillbirths, respectively. The percent agreement on GA within 7 and 28 days, respectively, was 85.9% and 100.0% for FTBs, 81.7% and 98.9% for PTBs, 61.3% and 94.7% for SAs, and 66.7% and 79.2% for stillbirths.

CONCLUSIONS

The pregnancy outcome algorithms had high agreement with physician adjudication of EMRs and may inform post-market maternal safety surveillance.

Impact of SARS-CoV-2 on pregnancy outcomes (Review)

The impact of the pandemic outbreak associated with coronavirus 2019 disease (COVID-19) on pregnant women is of interest to obstetricians and gynecologists due to the vulnerability of this target group. In pregnant women and their infants, an exceptional clinical management is warranted. Current epidemiological findings provide information regarding the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on pregnant patients and potential adverse perinatal outcomes. Overall, these findings are a strong indication that an increased antenatal surveillance for pregnant patients infected with COVID-19 is warranted. The aim of the present narrative review was to summarize the data obtained to date regarding the health of women during pregnancy, as well as that of the fetus associated with the risk of severe infection due to COVID-19. The present review aimed to provide further insight into the effects of this pandemic on pregnancy, also providing the experience of the authors on this matter as an example.

The association of COVID-19 infection in pregnancy with preterm birth: A retrospective cohort study in California

INTRODUCTION

Our understanding of the association between coronavirus disease 19 (COVID-19) and preterm or early term birth among racially and ethnically diverse populations and people with chronic medical conditions is limited.

METHODS

We determined the association between COVID-19 and preterm (PTB) birth among live births documented by California Vital Statistics birth certificates between July 2020 and January 2021 (n=240,147). We used best obstetric estimate of gestational age to classify births as very preterm (VPTB, <32 weeks), PTB (< 37 weeks), early term (37 and 38 weeks), and term (39-44 weeks), as each confer independent risks to infant health and development. Separately, we calculated the joint effects of COVID-19 diagnosis, hypertension, diabetes, and obesity on PTB and VPTB.

FINDINGS

COVID-19 diagnoses on birth certificates increased for all racial/ethnic groups between July 2020 and January 2021 and were highest for American Indian/Alaska Native (12.9%), Native Hawaiian/Pacific Islander (11.4%), and Latinx (10.3%) birthing people. COVID-19 diagnosis was associated with an increased risk of VPTB (aRR 1.6, 95% CI [1.4, 1.9]), PTB (aRR 1.4, 95% CI [1.3, 1.4]), and early term birth (aRR 1.1, 95% CI [1.1, 1.2]). There was no effect modification of the overall association by race/ethnicity or insurance status. COVID-19 diagnosis was associated with elevated risk of PTB in people with hypertension, diabetes, and/or obesity.

INTERPRETATION

In a large population-based study, COVID-19 diagnosis increased the risk of VPTB, PTB, and early term birth, particularly among people with medical comorbidities. Considering increased circulation of COVID-19 variants, preventative measures, including vaccination, should be prioritized for birthing persons.

FUNDING

UCSF-Kaiser Department of Research Building Interdisciplinary Research Careers in Women's Health Program (BIRCWH) National Institute of Child Health and Human Development (NICHD) and the Office of Research on Women's Health (ORWH) [K12 HD052163] and the California Preterm Birth Initiative, funded by Marc and Lynn Benioff.

COVID-19 Vaccination in Pregnancy and Lactation: Current Research and Gaps in Understanding

The COVID-19 pandemic has demonstrated the urgent need to develop vaccine strategies optimized for pregnant people and their newborns, as both populations are at risk of developing severe disease. Although not included in COVID-19 vaccine development trials, pregnant people have had access to these vaccines since their initial release in the US and abroad. The rapid development and distribution of novel COVID-19 vaccines to people at risk, including those who are pregnant and lactating, presents an unprecedented opportunity to further our understanding of vaccine-induced immunity in these populations. In this review, we aim to summarize the literature to date on COVID-19 vaccination in pregnancy and lactation and highlight opportunities for investigation that may inform future maternal vaccine development and implementation strategies.