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

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 Altruism and community benefit superseded personal benefit as reasons for vaccination.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.