The effect of COVID‐19 and COVID‐19 vaccination on serum anti‐Mullerian hormone: A systematic review and meta‐analysis

Abstract Objective The current study aims to evaluate the impact of COVID‐19 infection and vaccination on ovarian reserve by detecting the anti‐Mullerian hormone (AMH) level. Method PubMed, Embase, Web of Science, and Scopus has been searched for studies assessing the effect of COVID‐19 infection and/or vaccination on AMH levels up to February 27, 2023. Based on PRISMA 2020 statement criteria, a systematic review and meta‐analysis of included studies were performed. The studies' quality was assessed by the National Institute of Health (NIH) quality assessment tool. The standardized mean difference (MD) of the AMH level was used and the quantitative values of each study were pooled separately by using a random effect model. Results Out of 246 studies screened, 18 were included in the systematic review and 14 in the meta‐analysis. Included studies were published between 2021 and 2022 and were conducted in different countries, including the USA (n = 3), China (n = 2), Russia (n = 2), Turkey (n = 5), Israel (n = 3), Czech (n = 2), and Spain (n = 1). Eight studies investigated the effect of SARS‐CoV‐2 infection on AMH levels, and ten studies investigated the possible effect of COVID‐19 vaccination on AMH levels. The pooled analysis showed a statistically significant decrease in AMH levels after COVID‐19 infection (SMD: −0.24; 95% CI: −0.36 to −0.11; I2 = 0%; p = .0003). Vaccination analysis showed a nonstatistically significant change in AMH levels after COVID‐19 vaccination (SMD: −0.11; 95% CI: −0.25 to 0.04; I2 = 35%; p = .14). Conclusion COVID‐19 infection can result in ovarian reserve injury by reducing the AMH level but getting vaccinated against COVID‐19 has no impact on the AMH level.

Since early December 2019, when the COVID-19 pandemic began, billions of people worldwide have been impacted in various ways and the pandemic has presented immense challenges for public health. 1The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is primarily transmitted through respiratory droplets and physical contact. 2 COVID-19 has been found to affect not only the respiratory system, but also a range of other organs, including the cardiovascular, immune, and urinary systems, leading to a variety of disorders such as coagulopathy, disseminated intravascular coagulation, sepsis, and acute kidney injury. 3,46][7][8] Since then, over 11 billion vaccine doses have been administered worldwide. 9,10Although the vaccine has played a vital role in the pandemic,, it is reported that vaccination can lead to short-term menstrual distributions. 11oronavirus particles contain a spike protein (S) on their outer surface which can bind to the human cell surface receptor of angiotensin-converting enzyme 2 (ACE2) strongly which can trigger the immune system. 12Since the ACE2 receptors are highly expressed in uterine, placental, and ovarian cells, there would be possible if COVID-19 infection can affect fertility in women. 13][19] Anti-Müllerian hormone (AMH) is a glycoprotein produced by the ovarian preantral and small antral follicles which are known as a predictor of ovarian reserve estimation. 20,21AMH is the only reproductive hormone that is not influenced by different states of the menstrual cycle. 21And accounts for the prediction of ovarian response to ovarian stimulation. 22here are studies suggesting that COVID-19 vaccination does not have an effect on male or female fertility, 5 although it is questioned whether vaccines could have a subclinical effect on female fertility factors such as AMH.
Due to the immense number of women who have gotten infected by COVID-19 or get vaccinated against it, the present systematic review and meta-analysis is conducted to evaluate the effect of COVID-19 infection and vaccination on women's fertility by their influence on AMH.

| Search strategy
The present systematic review and meta-analysis have been conducted in accordance with the Cochrane Handbook. 23We have used The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) for the current study. 24

| Study selection and data extraction
The inclusion criteria were as follows 1 : patient population: women of reproductive age after getting infected by COVID-19 or getting vaccinated against it with at least one dose 2 ; Intervention: Vaccination with COVID-19 vaccines or getting infected by COVID-19 3 ; Comparison: women of reproductive age not vaccinated against COVID-19 or prior vaccination against COVID-19 or women of reproductive age who have not been infected by COVID-19 4 ; Outcome: impact on the Anti-Mullerian hormone (AMH) level 5 ; Setting/Time: All and 6 study design: randomized controlled trial, retrospective studies, and prospective studies.
Exclusion criteria were as follows: studies conducted on animals or minors and all study design other than the ones which were mentioned before including case reports, and case series.
Articles based on their title, abstract, and then full text has been screened by two reviewers in the Endnote, independently.All disagreements were resolved via discussion with a third reviewer to reach an agreement.Data were extracted via texts, tables, graphs, supplementary materials, and figures and were imported into an excel spreadsheet.Two reviewers have extracted characteristics data including Author, country, and year of publication, number of patients in each study, study type, and outcomes.

| Quality assessment
Two reviewers assessed the quality of the included studies using the National Heart, Lung, and Blood Institute (NHLBI)/National Institutes of Health (NIH) Quality Assessment tool.For the prepost studies, they used a 12-item assessment, while for the other studies, a 14-item assessment was employed. 25Studies were classified into three groups (good, fair, and poor) based on the scoring.Disagreements were resolved by discussion with the third reviewer.

| Outcome measure
Our outcome was assessing female fertility by measuring the effect of COVID-19 and COVID-19 vaccination on AMH level.

| Data synthesis and analysis
The standardized mean difference (MD) of the AMH level was used and the quantitative values of each study were pooled separately by using a random effect model.Excel calculator was used to estimate the MD if it was not reported.For assessing heterogeneity, Cochran's Q statistic (Q-test) and the I2 were used.I2 value > 75% indicated a high amount of heterogeneity.visual inspection of the funnel plot was used to assess publication bias and Egger's test with a significance level of 0.05 was used to evaluate the publication bias.Associations where the p-value < .05were considered significant.RevMan 5.4 and R-4.1.3software and the Meta package (R Core Team, Vienna, Austria; available at https://www.Rproject.org/,accessed on 6, January 2022) were used for analysis.

| Literature search
The initial database search yielded a total of 264 studies.After removing duplicates and screening based on title and abstract, 173 studies were identified for full-text review.After applying inclusion and exclusion criteria, a total of 15 studies were included in the final systematic review.The study selection process is presented in the PRISMA flow diagram (Figure 1).

| Baseline characteristics
The 18 included studies were published between 2021 and 2023 and were conducted in different countries, including the USA (n = 3), China (n = 2), Russia (n = 2), Turkey (n = 5), Israel (n = 3), Czech (n = 2) and Spain (n = 1).5][36][37][38][39][40][41][42] Six studies used m-RNA vaccines, one used the Russian GAM-COVID vaccine, two studies used CoronaVacc, and two did not report the type of vaccines used.All studies were observational, including prospective and retrospective studies.The total number of participants included in the COVID-19 analysis was 618, and the total number of participants included in the vaccination analysis was 1681.

| Quality assessment
The quality assessment using the National Heart, Lung, and Blood Institute (NHLBI) showed that no study was rated as poor quality, with specific detail about each study assessment rate in Table S3.

| COVID-19 analysis
The detailed characteristics of the included studies in COVID-19 analysis are presented in Table 1.The main outcome of this analysis was the effect of COVID-19 infection on AMH levels in women of reproductive age.The pooled analysis showed a statistically significant decrease in AMH levels after COVID-19 infection (SMD: −0.24; 95% CI: −0.36 to −0.11; I2 = 0%; p = .0003)(Figure 2).Subgroup analysis based on study design did not show a statistically significant between-group difference (p = .6910).The funnel plot showed no evidence of publication bias (Figures S1 and S2), and Egger's test was not applicable because fewer than 10 studies were included in our analysis.Furthermore, the sensitivity analysis results did not alter the statistically significant association (Figure S3).

| Vaccination analysis
The detailed characteristics of the included studies in Vaccination analysis are presented in Table 2.The main outcome of this analysis was the effect of COVID-19 vaccination on AMH levels in women of reproductive age.The pooled analysis showed a nonstatistically significant change in AMH levels after COVID-19 vaccination (SMD: -0.11; 95% CI: −0.25 to 0.04; I2 = 35%; p = .14)(Figure 3A).Subgroup analysis based on study design did not show a statistically significant between-group difference (p = .69).The funnel plot showed no evidence of publication bias (Figures S4  and S5), and Egger's test was not applicable because fewer than 10 studies were included in our analysis.Furthermore, the sensitivity analysis results did not alter the nonstatistically significant association (Figure S6).In addition to the above analysis, we performed a binary meta-analysis on the odds of lower than predefined cutoff AMH after vaccination, our results showed a nonstatistically significant trend regarding the protective effect of vaccination on AMH (OR: 0.44; 95% CI: 0.19 to 1.01; I2 = 0%; p = .05)(Figure 3B).

| DISCUSSION
The present systematic review aimed to investigate the effect of SARS-CoV-2 infection and COVID-19 vaccination on anti-Mullerian hormone (AMH) levels in women of reproductive age.Our search yielded 15 studies that met the inclusion criteria, including eight studies that investigated T A B L E 1 Characteristics of studies investigating the effect of COVID-19 on anti-müllerian hormone (AMH) levels.the effect of SARS-CoV-2 infection on AMH levels and seven studies that investigated the effect of COVID-19 vaccination on AMH levels.The results indicated a significant decrease in AMH levels following SARS-CoV-2 infection in women of reproductive age.On the other hand, our analysis showed a nonsignificant change in AMH levels after COVID-19 vaccination.However, the binary metaanalysis showed a nonsignificant trend regarding the protective effect of vaccination on AMH levels.The sensitivity analysis did not alter the significant association found, which indicates the robustness of our results.It is important to note that the studies included in our analysis used different types of COVID-19 vaccines, with four studies using mRNA vaccines and one study using the Russian GAM-COVID vaccine.Additionally, two studies did not report the type of vaccine used.In a systematic review and meta-analysis study by Zaçe et al. researchers reviewed effect of COVID-19 vaccination (Gam-COVID-Vac and BNT162b2) on different outcomes such as sperm characteristics, steroid hormones levels, biochemical and clinical pregnancy rate; no significant finding was reported and authors concluded that COVID-19 vaccinations is not associated with impaired fertility outcomes. 5Vaccination with mRNA vaccines also showed no change in gametes and embryo parameters. 43Hasdemir et al. study was the only one reporting a significant decrease in level of AMH among vaccinated patients, they compared AMH level among healthcare workers pre and post vaccination.They measured AMH levels several time post vaccinations and AMH levels were only measured once before vaccination.The fact that COVID-19 was not an exclusion criterion in their study, plus participants being health care workers with high exposer to SARS-CoV-2 virus, could affect the findings of this study.Although it must be noted that level of AMH was above normal range and the increase was mostly transient. 44Overall COVID-19 vaccination seems to be safe regarding female laboratory and clinical fertility outcomes.COVID-19 could affect menstrual cycles in women and cause irregular menstruation, oligomenorrhea and increase premenopausal syndrome. 45In a systematic review and meta-analysis by Cai et al. effect of COVID-19 on sex steroids was reviewed.Patients with COVID-19 history had significantly lower testosterone to LH ratio, FSH to LH ratio and sex hormone-binding globulin (SHBG) levels.Levels of LH was higher in COVID-19 patients compared to control. 1 Although both our study and Cai et al. study found a significant alternation in fertility related lab findings but there is no long term follow up studies assessing fertility and fecundity of patients with a history of COVID-19.

Author
To discuss the possible underlying pathogenesis, we know that SARS-CoV2 uses Angiotensin converting enzyme (ACE) receptor to infect the host cells. 46On the other hand, there is evidence regarding presence of this receptor in ovaries, 47 so the effect of COVID-19 on AMH level, which is reported in this study, could be due to direct involvement of ovaries.This statement is consistent with findings of a study by Naigaonkar et al. that reported a lower rate of ovarian involvement among COVID-19 women with less "coronavirus-associated receptors and factors". 48Transmembrane serine protease 2 (TMPRSS2) is the other entry molecule of SARS-CoV-2 and co-expression of TMPRSS2 and ACE is also observed in ovary cells. 49Another possible mechanism could be the effect of hyperinflammatory state caused by COVID-19. 50We know that COVID-19 is associated with hyperinflammatory immune response that could lead to multi organ damages including ovaries and level of AMH. 51urther research is required to address whether the effect of COVID-19 and vaccination on AMH is permanent or temporary, and long term follow up studies should be conducted to assess reproductive outcomes.The available evidence is limited to suggest that there may be variations in the influence on AMH levels depending on the type of vaccine administered.Studies   34 However, it is important to note that findings across studies are not uniform, and additional research is needed to elucidate the specific mechanisms and longterm implications of COVID-19 vaccination on reproductive health.Moreover, the heterogeneity in study designs, populations, and methodologies underscores the complexity of this relationship, necessitating further exploration for a comprehensive understanding of the interplay between different COVID-19 vaccines and AMH levels.The strengths of this study include the comprehensive literature search, strict inclusion and exclusion criteria, quality assessment of included studies and low heterogeneity among included studies.However, this study has some limitations.Firstly, low number of included studies in each analysis and different types of vaccines compared together.
In conclusion, this systematic review provides evidence of a significant decrease in AMH levels after COVID-19 infection in women of reproductive age.However, we found no significant change in AMH levels after COVID-19 vaccination.These findings suggest that COVID-19 infection may have a negative impact on ovarian reserve, and further research is required to assess reproductive outcomes among COVID-19 survivors.Nevertheless, the effect of COVID-19 vaccination on ovarian reserve needs further investigation, given the limited number of studies included in our analysis.Overall, our findings provide valuable insights into the impact of COVID-19 on female reproductive health and may inform clinical practice and public health policies.

F I G U R E 2 1 -
Results of a COVID-19 analysis.T A B L E 2 Characteristics of studies investigating the effect of COVID-19 vaccination on anti-müllerian hormone (AMH) levels.Vaccine has no adverse effect on ovarian reserve in women 2-p-value for AMH before and after the vaccine is .medianAMH concentrations before and after COVID-19 vaccine did not change significantly (p = .96).2-No correlation was found between the participant's anti-COVID-19 antibody titer and the change in AMH concentrationAMH levels were 5.3 ( §SD 4.29) mg/L and 5.3 ( §SD 4.50) mg/l before vaccination and after 3 months, respectively (p = .11)2-There was no significant difference before and after the vaccine Palmerola, K. L.