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

COVID-19 infection history as a risk factor for early pregnancy loss: results from the electronic health record-based Southeast Texas COVID and Pregnancy Cohort Study

BACKGROUND

The effects of SARS-CoV-2 infection before or during pregnancy on pregnancy outcomes are still largely unknown. We hypothesized that COVID-19 in early pregnancy is a risk factor for adverse pregnancy outcomes, particularly miscarriage.

METHODS

We examined the relationship between COVID-19 and adverse pregnancy outcomes, including spontaneous abortion, ectopic pregnancy, and preterm delivery in a large, retrospective, electronic health record (EHR)-based cohort, from 2019 to 2023. Generalized estimating equation modeling was performed to identify risk factors for adverse pregnancy outcomes. Study exposures included COVID-19 before pregnancy, COVID-19 during pregnancy, age, race/ethnicity, comorbidity burden, and neighborhood-level social vulnerability.

RESULTS

In the Southeast Texas Pregnancy and COVID Cohort (26,783 pregnancy episodes), the risk of miscarriage among pregnancy episodes with a miscarriage, livebirth, or delivery outcome was 6.3% (1514/ 24,119). In multivariable modeling, history of both mild and moderate to severe COVID-19 before pregnancy were associated with miscarriage (adjusted odds ratio (aOR) 2.48, confidence interval (CI) 2.21-2.78 and aOR 2.81, CI 1.8-4.38, respectively). Additionally, in the same model, both mild and moderate to severe COVID-19 in the first trimester were associated with miscarriage (aOR 2.31, CI 1.96-2.72 and aOR 2.45, CI 1.12-5.35, respectively).

CONCLUSIONS

COVID-19 both prior to and during pregnancy was identified as a risk factor for spontaneous abortion in this study sample. These findings highlight the importance of COVID-19 vaccination and post-COVID management for pregnant people and those planning a pregnancy.

Maternal Exposures to COVID-19 Vaccine and Adverse Birth Outcomes: National Population Study in Korea

BACKGROUND

This study aimed to estimate the association between mRNA coronavirus disease 2019 (COVID-19) vaccine exposure during pregnancy and the risks of preterm birth and congenital malformations leveraging a national population data.

METHODS

This retrospective cohort study utilized national data from the National Health Insurance System, linking maternal and infant records with COVID-19 vaccination registries. Newborns with congenital malformations were identified using diagnosis codes. The analysis included women aged 20-49 who gave live births between February 2022 and December 2022. Odds ratios (ORs) for preterm birth and any congenital malformation per COVID-19 vaccination during pregnancy compared to 1:4 matched unvaccinated controls, adjusted for maternal age, residential area, employment, income, disability, month of conception, pre-pregnancy obesity, smoking, and severe acute respiratory syndrome coronavirus 2 infection prior to pregnancy, were calculated. We compared the risk of two outcomes between BNT162b2 and mRNA-1273.

RESULTS

Among 106,692 women who gave birth during the study period, 8,966 (8.4%) received a COVID-19 vaccination during pregnancy. Of the newborns, 7,039 (6.6%) were preterm births and 7,658 (7.2%) had congenital malformations. COVID-19 vaccination during pregnancy was associated with a comparable risk of preterm birth (OR, 1.03; 95% confidence interval [CI], 0.77-1.36) and a similar risk of congenital malformations (0.90; 95% CI, 0.72-1.12) compared to non-vaccinees. The ORs of preterm birth (1.02; 95% CI, 0.77-1.36) and congenital malformation (0.91; 95% CI, 0.73-1.14) for mRNA-1273 were comparable to those for BNT162b2.

CONCLUSION

COVID-19 vaccines during pregnancy poses no increased risk of preterm birth and congenital malformations compared to those not exposed to the vaccine, with similar risk levels observed between the two mRNA vaccines. This finding provides additional evidence supporting the safety of COVID-19 vaccines.

COVID-19 vaccination rates among pregnant women in France: A nationwide cohort study

BACKGROUND

Pregnant women are at an elevated risk for severe COVID-19, but nationwide rates of vaccination and its timing during pregnancy are not well documented in France.

OBJECTIVES

To assess COVID-19 vaccination rates among pregnant women in France, compare them to those of the general population, and analyse factors associated with vaccination status and timing.

METHODS

A nationwide study using the EPI-MERES register, which includes all 1,203,454 pregnant women who delivered between April 2021 and December 2022 in France. Standardization by age and social index was used to compare vaccination rates with those of the general female population. Associations with sociodemographic factors, pregnancy monitoring indicators, and pre-existing comorbidities were measured using multivariable logistic regression.

RESULTS

Overall, 52 % of pregnant women received at least one vaccine dose, with 62.1 % vaccinated before conception and 8.2 %, 20.9 %, and 8.8 % vaccinated in the 1st, 2nd, and 3rd trimester, respectively. Vaccination rates initially lagged behind those of the general population but converged by June 2022, with a six-month lag. Younger and more socially deprived women were less highly vaccinated. Unvaccinated women were more likely to be in their third pregnancy (aOR, 1.21 [1.19-1.22]), had fewer ultrasound scans (aOR, 0.71 [0; 70-0.73]), and less often took folic acid (aOR, 0.73 [0.72-0.74]). Women with comorbidities, such as obesity, diabetes, hypertension, antidepressant use, or chronic respiratory disease, were less likely to be unvaccinated (aORs ranged from 0.69 to 0.89).

CONCLUSIONS

Pregnant women in France were less highly vaccinated than the general population during crucial pandemic periods but eventually reached similar vaccination rates. Socioeconomic status and the level of prenatal care were strongly associated with low vaccine uptake. This should be a focus for future interventions and policy adjustments across all segments of this population.

Effect of the COVID-19 vaccination on feto-maternal outcomes: A prospective cohort study among Indian pregnant women

Background & objectives Studies on the effects of COVID-19 vaccination among pregnant women in Asian settings, more specifically in India, are scarce. The present study evaluated the feto-maternal outcomes among Indian pregnant women who received the COVID-19 vaccine. Methods A prospective cohort study was undertaken among 430 pregnant women from two primary health centres (PHC) in Chandigarh, India during 2021-2022. The feto-maternal outcomes evaluated in the study included abortions, live birth/stillbirth, term/pre-term/post-term delivery, mode of delivery (normal vaginal/caesarean section/forceps), birth weight and intrauterine growth retardation. Results Of the 430 study participants, 295 pregnant women received COVID-19 vaccines, with an uptake rate of 68.6 per cent. Majority of vaccinated women (280- who completed the study) were in their second trimester (133, 47.5%), while 92 (32.9%) were in their third, and 55 (19.6%) were in their first trimester when they were enrolled in the study. Neonatal intensive care unit (NICU) admission was significantly lower among the vaccinated pregnant women, while other feto-maternal and neonatal outcomes were similar between vaccinated and unvaccinated pregnant women. Interpretation & conclusions The findings of this study suggest COVID-19 vaccination in pregnant women in India might be safe, in terms of feto-maternal outcomes.

COVID-19 Vaccine Safety in Pregnancy, A Nested Case-Control Study in Births From April 2021 to March 2022, England

OBJECTIVE

Assessment of COVID-19 vaccine safety in pregnancy using population-based data.

DESIGN

Matched case-control study nested in a retrospective cohort.

SETTING

April 2021-March 2022, England.

POPULATION OR SAMPLE

All pregnant individuals aged between 18 and 50 years with valid health records.

METHODS

Individuals identified from the national Maternity Services Data Set (MSDS) had their records linked to hospital admission, national COVID-19 vaccine and COVID-19 testing databases. Matching included participant's age and estimated week of conception. We compared outcomes across multiple COVID-19 vaccine exposures using conditional multivariable logistic regression, adjusting for demographic and health characteristics.

MAIN OUTCOME MEASURES

Adverse pregnancy, maternal and neonatal outcomes.

RESULTS

514 013 individuals were included. We found lower odds of giving birth to a baby who was low birthweight (aOR = 0.86, 95% CI: 0.79-0.93), preterm (aOR = 0.89, 95% CI: 0.85-0.92) or who had an Apgar score < 7 at 5 min of age (aOR = 0.89, 95% CI: 0.80-0.98) for individuals who received at least one dose of COVID-19 vaccine during pregnancy. The odds of admission to intensive care unit during pregnancy were lower in those vaccinated (aOR = 0.85, 95% CI: 0.76-0.95). There was no association between vaccination in pregnancy and stillbirth, neonatal death, perinatal death and maternal venous thromboembolism in pregnancy.

CONCLUSIONS

COVID-19 vaccines are safe to use in pregnancy. Our findings generated important information to communicate to pregnant individuals and health professionals to support COVID-19 maternal vaccination programmes.

Safety and Effectiveness of COVID-19 Vaccines During Pregnancy: A Living Systematic Review and Meta-analysis

BACKGROUND

Pregnant persons are susceptible to significant complications following COVID-19, even death. However, worldwide COVID-19 vaccination coverage during pregnancy remains suboptimal.

OBJECTIVE

This study assessed the safety and effectiveness of COVID-19 vaccines administered to pregnant persons and shared this evidence via an interactive online website.

METHODS

We followed Cochrane methods to conduct this living systematic review. We included studies assessing the effects of COVID-19 vaccines in pregnant persons. We conducted searches every other week for studies until October 2023, without restrictions on language or publication status, in ten databases, guidelines, preprint servers, and COVID-19 websites. The reference lists of eligible studies were hand searched to identify additional relevant studies. Pairs of review authors independently selected eligible studies using the web-based software COVIDENCE. Data extraction and risk of bias assessment were performed independently by pairs of authors. Disagreements were resolved by consensus. We performed random-effects meta-analyses of adjusted relative effects for relevant confounders of comparative studies and proportional meta-analyses to summarize frequencies from one-sample studies using R statistical software. We present the GRADE certainty of evidence from comparative studies. Findings are available on an interactive living systematic review webpage, including an updated evidence map and real-time meta-analyses customizable by subgroups and filters.

RESULTS

We included 177 studies involving 638,791 participants from 41 countries. Among the 11 types of COVID-19 vaccines identified, the most frequently used platforms were mRNA (154 studies), viral vector (51), and inactivated virus vaccines (17). Low to very low-certainty evidence suggests that vaccination may result in minimal to no important differences compared to no vaccination in all assessed maternal and infant safety outcomes from 26 fewer to 17 more events per 1000 pregnant persons, and 13 fewer to 9 more events per 1000 neonates, respectively. We found statistically significant reductions in emergency cesarean deliveries (9%) with mRNA vaccines, and in stillbirth (75-83%) with mRNA/viral vector vaccines. Low to very low-certainty evidence suggests that vaccination during pregnancy with mRNA vaccines may reduce severe cases or hospitalizations in pregnant persons with COVID-19 (72%; 95% confidence interval [CI] 42-86), symptomatic COVID-19 (78%; 95% CI 21-94), and virologically confirmed SARS-CoV-2 infection (82%; 95% CI 39-95). Reductions were lower with other vaccine types and during Omicron variant dominance than Alpha and Delta dominance. Infants also presented with fewer severe cases or hospitalizations due to COVID-19 and laboratory-confirmed SARS-CoV-2 infection (64%; 95% CI 37-80 and 66%; 95% CI 37-81, respectively).

CONCLUSIONS

We found a large body of evidence supporting the safety and effectiveness of COVID-19 vaccines during pregnancy. While the certainty of evidence is not high, it stands as the most reliable option available, given the current absence of pregnant individuals in clinical trials. Results are shared in near real time in an accessible and interactive format for scientists, decision makers, clinicians, and the general public. This living systematic review highlights the relevance of continuous vaccine safety and effectiveness monitoring, particularly in at-risk populations for COVID-19 impact such as pregnant persons, during the introduction of new vaccines.

CLINICAL TRIAL REGISTRATION

PROSPERO: CRD42021281290.

COVID-19 vaccination and birth outcomes of 186,990 women vaccinated before pregnancy: an England-wide cohort study

Background

COVID-19 vaccination in pregnancy is recommended by the World Health Organisation as effective and safe. However, there remains a lack of robust evidence to inform vaccination choices for women of childbearing potential in relation to their future pregnancies. Here we investigated the association between starting a course of COVID-19 vaccination before pregnancy and birth outcomes.

Methods

We analysed England-wide linked electronic health records for all pregnancies reaching at least 24 weeks gestation between 25th May 2021 and 28th October 2022. We estimated incidence rates and hazard ratios for birth and pregnancy outcomes by pre-pregnancy COVID-19 vaccination status.

Findings

Based on 186,990 women, compared to starting a pregnancy unvaccinated, receiving COVID-19 vaccination within 12 months before pregnancy was associated with lower risks of very and extremely preterm birth and small-for-gestational age in term babies for any vaccine type (adjusted hazard ratio and 95% confidence interval: 0.74 [0.63, 0.88] and 0.94 [0.88, 1.00], respectively), and lower stillbirth risk in those receiving an mRNA vaccine (0.72 [0.52, 1.00]). Incidence of venous thromboembolism during pregnancy was higher amongst women receiving a viral-vector, but not an mRNA vaccine (1.54 [1.10, 2.16] and 1.02 [0.70, 1.50], respectively). Results were generally consistent for different dose regimens and across sensitivity analyses.

Interpretation

We found evidence that pregnancies starting within 12 months from a first COVID-19 vaccination, compared to those in unvaccinated women, experienced fewer adverse birth outcomes, overall or in selected subgroups of the general population, accounting for potential confounders. An mRNA vaccine should be preferred to a viral-vector vaccine, to minimise safety issues, but where the latter is the only choice, it is still to be preferred to starting a pregnancy unvaccinated. The venous thromboembolism risk of the viral-vector vaccine was substantially lower compared to that attributable to SARS-CoV-2 infection in pregnancy or to commonly used medications such as hormone replacement therapy and oral contraceptives in the non-pregnant population.

Funding

UK National Institute for Health and Care Research (NIHR), UKRIMedical Research Council, UK Research and Innovation, The Alan Turing Institute, Health Data Research UK, the Department of Health and Social Care.

Birth rate decline in the later phase of the COVID-19 pandemic: the role of policy interventions, vaccination programmes, and economic uncertainty

STUDY QUESTION

What are the factors influencing the decline in the birth rates observed in higher-income countries in the later phase of the COVID-19 pandemic?

SUMMARY ANSWER

Our results suggest that economic uncertainty, non-pharmaceutical policy interventions, and the first wave of the population-wide vaccination campaign were associated with the decline in birth rates during 2022.

WHAT IS KNOWN ALREADY

During the COVID-19 pandemic, birth rates in most higher-income countries first briefly declined and then shortly recovered, showing no common trends afterwards until early 2022, when they unexpectedly dropped.

STUDY DESIGN SIZE DURATION

This study uses population-wide data on monthly total fertility rates (TFRs) adjusted for seasonality and calendar effects provided in the Human Fertility Database (HFD). Births taking place between November 2020 and October 2022 correspond to conceptions occurring between February 2020 and January 2022, i.e. after the onset of the pandemic but prior to the Russian invasion of Ukraine. The data cover 26 countries, including 21 countries in Europe, the USA, Canada, Israel, Japan, and the Republic of Korea.

PARTICIPANTS/MATERIALS SETTING METHODS

First, we provided a descriptive analysis of the monthly changes in the TFR. Second, we employed linear fixed effects regression models to estimate the association of explanatory factors with the observed seasonally adjusted TFRs. Our analysis considered three broader sets of explanatory factors: economic uncertainty, policy interventions restricting mobility and social activities outside the home, and the progression of vaccination programmes.

MAIN RESULTS AND THE ROLE OF CHANCE

We found that birth trends during the COVID-19 pandemic were associated with economic uncertainty, as measured by increased inflation (P < 0.001), whereas unemployment did not show any link to births during the pandemic (P = 0.677). The stringency of pandemic policy interventions was linked to a postponement of births, but only in countries with lower institutional trust and only in the early phase of the pandemic (P = 0.003). In countries with higher trust, stricter containment measures were positively associated with birth rates, both for conceptions in the first year of the pandemic (P = 0.019) and, albeit only weakly significant, for conceptions later in the pandemic (P = 0.057). Furthermore, we found a negative association between the share of the population having received the first dose of the COVID-19 vaccination and TFRs (P < 0.001), whereas the share of the population having completed the primary vaccination course (usually consisting of two doses) was linked to a recovery of birth rates (P < 0.001).

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

Our research is restricted to higher-income countries with relatively strong social support policies provided by the government as well as wide access to modern contraception. Our data did not allow analyses of birth trends by key characteristics, such as age, birth order, and social status.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first multi-country study of the drivers of birth trends in the later phase of the COVID-19 pandemic. In the past, periods following epidemics and health crises were typically associated with a recovery in births. In contrast, our results show that the gradual phasing out of pandemic containment measures, allowing increased mobility and a return to more normal work and social life, contributed to declining birth rates in some countries. In addition, our analysis indicates that some women avoided pregnancy until completion of the primary vaccination protocol.

STUDY FUNDING/COMPETING INTERESTS

This study did not use any external funding. The authors acknowledge funding from their home institution, the Vienna Institute of Demography of the Austrian Academy of Sciences, and from the Open-Access Fund of the Austrian Academy of Sciences. For the purpose of open access, the authors have applied a CC BY public copyright licence to any Author Accepted Manuscript versions arising from this submission. All authors declare that they have no conflicts of interest.

Courage in Decision Making: A Mixed-Methods Study of COVID-19 Vaccine Uptake in Women of Reproductive Age in the U.K

COVID-19 vaccination rates are lower in women of reproductive age (WRA), including pregnant/postpartum women, despite their poorer COVID-19-related outcomes. We evaluated the vaccination experiences of 3568 U.K. WRA, including 1983 women (55.6%) experiencing a pandemic pregnancy, recruited through the ZOE COVID Symptom Study app. Two staggered online questionnaires (Oct-Dec 2021: 3453 responders; Aug-Sept 2022: 2129 responders) assessed reproductive status, COVID-19 status, vaccination, and attitudes for/against vaccination. Descriptive analyses included vaccination type(s), timing relative to age-based eligibility and reproductive status, vaccination delay (first vaccination >28 days from eligibility), and rationale, with content analysis of free-text comments. Most responders (3392/3453, 98.2%) were vaccinated by Dec 2021, motivated by altruism, vaccination supportiveness in general, low risk, and COVID-19 concerns. Few declined vaccination (by Sept/2022: 20/2129, 1.0%), citing risks (pregnancy-specific and longer-term), pre-existing immunity, and personal/philosophical reasons. Few women delayed vaccination, although pregnant/postpartum women (vs. other WRA) received vaccination later (median 3 vs. 0 days after eligibility, p < 0.0001). Despite high uptake, concerns included adverse effects, misinformation (including from healthcare providers), ever-changing government advice, and complex decision making. In summary, most women in this large WRA cohort were promptly vaccinated, including pregnant/post-partum women. Altruism and community benefit superseded personal benefit as reasons for vaccination. Nevertheless, responders experienced angst and received vaccine-related misinformation and discouragement. These findings should inform vaccination strategies in WRA.

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.

Lack of association between COVID-19 vaccines and miscarriage onset using a case-crossover design

Pregnant women might have an increased risk of SARS-COV-2 infection. Although evidence towards the efficacy and safety of COVID-19 is growing still there is room for improvement on the knowledge towards pregnancy adverse events, such as miscarriage. We explored the association of COVID-19 vaccine with the risk of miscarriages using the Real-World. We identified a cohort of vaccinated pregnancies using the BIFAP database which contains systematically recorded data on care patients in Spain (N = 4054). We then restricted it to those women who had a miscarriage using a validated algorithm (N = 607). Among them, we performed a case-crossover design to evaluate the effect of intermittent exposures on the risk of miscarriage. Adjusted Odds Ratio with their confidence intervals were calculated using two analytical approaches: conditional logistic regression and Generalized Linear Mixed-Effects Models. A total of 225 (37.1%) were aged 35-39 years. The most common comorbidities were asthma, migraine, gastritis, and hypothyroidism. A total of 14.7% received only one dose of COVID-19 and 85.3% two doses, respectively. A total of 36.8% of women with one dose and 27.6% with two doses received the vaccine 7 days prior to the miscarriage. Corresponding adjusted estimates for the risk of miscarriage using the conditional logistic regression where as follows: 1.65 (95% CI 0.85-3.23) when using as the sum of 3 control moments among women with one dose, 1.02 (95% CI 0.72-1.46) among women with two doses and 1.03 (95% CI 0.72, 1.46) using the whole study population. Very similar results were obtained when conducting the Generalized Linear Mixed-Effects Models. There was no overall increased risk of miscarriage onset associated with COVID-19 vaccine although contradictory results were found according to the number of doses. Further studies are required with larger sample sizes to assess this association.

Miscarriage after SARS-CoV-2 vaccination: A population-based cohort study

OBJECTIVE

To evaluate the risk of miscarriage following SARS-CoV-2 vaccination, while accounting for the competing risk of induced abortion.

DESIGN

Population-based cohort study.

SETTING

Ontario, Canada.

PARTICIPANTS

Women aged 15-50 years with a confirmed pregnancy at ≤19 completed weeks' gestation.

METHODS

Exposure to first SARS-CoV-2 vaccination, handled in a time-varying manner, was defined as (i) unvaccinated, (ii) remotely vaccinated >28 days before the estimated conception date or (iii) recently vaccinated ≤28 days before conception and up to 120 days after conception.

MAIN OUTCOME MEASURES

The outcome was miscarriage, occurring between the estimated date of conception and up to 19 completed weeks of pregnancy. Fine-Grey hazard models, accounting for the competing risk of induced abortion, generated hazard ratios (aHR), adjusted for socio-demographic factors, comorbidities, and biweekly periods.

RESULTS

Included were 246 259 pregnant women, of whom 34% received a first SARS-CoV-2 vaccination. Miscarriage occurred at a rate of 3.6 per 10 000 person-days among remotely vaccinated women and 3.2 per 10 000 person-days among those recently vaccinated, in contrast to a rate of 1.9 per 10 000 person-days among unvaccinated women, with corresponding aHR of 0.98 (95% confidence interval [CI] 0.91-1.07) and 1.00 (95% CI 0.93-1.08).

CONCLUSIONS

SARS-CoV-2 vaccination was not associated with miscarriage while accounting for the competing risk of induced abortion. This study reiterates the importance of including pregnant women in new vaccine clinical trials and registries, and the rapid dissemination of vaccine safety data.

Safety of COVID-19 Vaccination During Pregnancy and Lactation: A VigiBase Analysis

BACKGROUND

There is limited evidence on the safety of coronavirus disease 2019 (COVID-19) vaccination during pregnancy and lactation. Thus, we aimed to evaluate the association between COVID-19 vaccination during pregnancy and lactation and reporting risk of adverse pregnancy or lactation outcomes.

METHODS

Using VigiBase, we performed a disproportionality analysis with case/non case design. Cases were defined based on the Standardized MedDRA Queries (SMQs) of "pregnancy and neonatal topics" and non-cases were defined as all other adverse events. We included all reports with COVID-19 vaccines as the suspected cause. Using the full database as the comparators, reporting odds ratios (RORs) with 95% confidence intervals (CIs) were estimated by logistic regression while adjusting for maternal age. Infants' age and sex were additionally adjusted in analyzing the risk of COVID-19 vaccination during lactation.

RESULTS

We identified 10,266 and 6,474 reports with the SMQ of "pregnancy and neonatal topics" associated with COVID-19 vaccines during pregnancy and lactation, respectively. No significant RORs of adverse pregnancy outcomes associated with COVID-19 vaccines during pregnancy were observed; however, "functional lactation disorders" showed significant disproportionality during lactation with adjusted ROR of 1.48 (95% CI, 1.21-1.79). Further analysis that analyzed "functional lactation disorders" at a preferred term level, showed higher ROR in mastitis (2.76 [95% CI, 1.45-5.27]).

CONCLUSION

Overall, we did not observe a positive association between COVID-19 vaccination during pregnancy and risk of reporting adverse pregnancy outcomes. However, we found a significant disproportionate reporting association between COVID-19 vaccination during lactation and "functional lactation disorders", specifically mastitis. Continuous surveillance is warranted to confirm the safety of COVID-19 vaccine during pregnancy and lactation.

AI language models in human reproduction research: exploring ChatGPT's potential to assist academic writing

Artificial intelligence (AI)-driven language models have the potential to serve as an educational tool, facilitate clinical decision-making, and support research and academic writing. The benefits of their use are yet to be evaluated and concerns have been raised regarding the accuracy, transparency, and ethical implications of using this AI technology in academic publishing. At the moment, Chat Generative Pre-trained Transformer (ChatGPT) is one of the most powerful and widely debated AI language models. Here, we discuss its feasibility to answer scientific questions, identify relevant literature, and assist writing in the field of human reproduction. With consideration of the scarcity of data on this topic, we assessed the feasibility of ChatGPT in academic writing, using data from six meta-analyses published in a leading journal of human reproduction. The text generated by ChatGPT was evaluated and compared to the original text by blinded reviewers. While ChatGPT can produce high-quality text and summarize information efficiently, its current ability to interpret data and answer scientific questions is limited, and it cannot be relied upon for a literature search or accurate source citation due to the potential spread of incomplete or false information. We advocate for open discussions within the reproductive medicine research community to explore the advantages and disadvantages of implementing this AI technology. Researchers and reviewers should be informed about AI language models, and we encourage authors to transparently disclose their use.

Effects of the Severe Acute Respiratory Syndrome Coronavirus 2 Inactivated Vaccine on the Outcome of Frozen Embryo Transfers: A Large Scale Clinical Study

Background

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a life-threatening infectious disease that has become a global pandemic.

Objective

This study aimed to explore the effects of SARS-CoV-2 inactivated vaccine on the outcome of frozen embryo transfer (FET).

Methods

We grouped patients who underwent FET between August 2021 and March 2022 based on their vaccination status, number of doses, and the interval between the last dose and the FET, and then compared the differences in pregnancy outcomes among the groups.

Results

There were 1084 vaccinated patients and 1228 non-vaccinated ones. There were significant differences in the live birth rate between the vaccination and non-vaccination groups (16.61% vs 28.26%), among the one-dose, two-dose, and three-dose groups (22.28% vs 19.51% vs 7.27%), and among the groups with interval ≤ 1 month, 1-2 months, and ≥ 2 months (38.38% vs 27.27% vs 12.03%). There were significant differences in the persistent pregnancy rate between the vaccination and non-vaccination groups (22.88% vs 14.09%), among the one-dose, two-dose, and three-dose groups (14.51% vs 23.80% vs 38.18%), and among the groups with interval ≤ 1 month, 1-2 months, and ≥ 2 months (1.01% vs 8.44% vs 28.16%). There were significant differences in the neonatal weight between the vaccination and non-vaccination groups [3805.50 (3746.00-3863.50) vs 2970.00 (2500.00-3400.00)]. There were significant differences in the premature birth rate among the one-dose, two-dose, and three-dose groups (23.26% vs 34.59% vs 100.00%), and among the groups with interval ≤ 1 month, 1-2 months, and ≥ 2 months (15.79% vs 21.43% vs 37.00%).

Conclusion

Pregnancy outcomes were not affected by taking the SARS-CoV-2 inactivated vaccine before FET, the number of doses, and the interval between doses. These findings provide evidence supporting the safety of administering the SARS-CoV-2 inactivated vaccine during pregnancy, which can be used as a guide for vaccinating patients undergoing ART.