The association between SARS-CoV-2 infection with menstrual characteristics changes in China: a cross-sectional study

Abstract Objective To evaluate the association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with menstrual changes, and analyze the possible related factors to menstrual changes. Methods A cross-sectional study based on online survey was conducted. Women who had been infected with SARS-CoV-2 completed the questionnaires voluntarily and were enrolled in this study. Participants were divided into menstrual change group and no menstrual change group, based on the presence or absence of menstrual changes. Results A total of 1016 women were enrolled, including 530 in the menstrual change group and 486 in the no menstrual change group. The three most common abnormalities were changes of menstruation cycles, menstruation flow and menstruation duration. Compared with the no menstrual change group, participants in the menstrual change group were significantly younger (32.55 ± 7.00 vs. 33.67 ± 7.39, p = .013), reported more severe symptoms with score ≥ 6 (32.1% vs. 21.1%), and had more severe mental health problems, showing nervous (22.6% vs. 17.3%, p = .009), anxiety (34.9% vs. 24.5%, p < .001), depression (14.7% vs. 8.2%, p = .003) and fear (10.8% vs. 6.4%, p = .011). Conclusions SARS-CoV-2 infection was associated with menstrual changes. The age, the severity of symptoms and mental health problems were related to menstrual changes.


Introduction
The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has exerted a huge impact on people's health all over the world.The potential negative impacts of COVID-19 on male and female reproduction function were reported by many studies [1-3].Menstruation, as the one of direct indicators for both ovarian and endometrial function, was found to be changed under the influence of SARS-Cov-2 infection.
A number of studies found that women with previous SARS-CoV-2 infection showed alterations in menstrual patterns, changes in the menstrual cycle length and menstruation flow [4,5].The frequency of menstrual irregularities following SARS-CoV-2 infection was reported to be 15% and 28% in two studies, respectively [6,7].The latter is the first study that shows an association between menstrual characteristics changes and the severity of COVID-19 in 20 SARS-CoV-2 positive participants [7].There was selection bias as studies included only hospitalized women with a small sample size, and cannot establish a causal relationship.In contrast, a prospective study reported that SARS-CoV-2 infection was not associated with changes in usual menstrual cycle characteristics in 421 infected women [8].So far, results from published literature were inconsistent and the association of COVID-19 with menstruation has not yet been fully elucidated.
Whether there is an association between SARS-CoV-2 infection/COVID-19 with menstrual changes?To explore this question, we conducted a cross-sectional study via an online survey, explored the association between them, and analyzed the possible related factors to menstrual changes.

Participants and recruitment
A cross-sectional study was conducted between 19 January 2023 and 18 February 2023.Data were collected through an online survey, using the WENJUANXING survey platform (http://www.wjx.cn).The present study was approved by the ethical committee of Xiangya Hospital, Central South University, piloted and available in China.
Participants were recruited through social media (WeChat), or nongovernmental organizations.The main inclusion criteria were: (1) menstruant; (2) SARS-CoV-2 infected; (3) live in China after relaxation of COVID-19 control policy.The participant was excluded when the questionnaire was not completed.

Questionnaire design
The questionnaire was determined by the research team after multiple rounds of discussion, including the general characteristics of the participants (age, ethnicity, marriage, body mass index [BMI], education, etc.), information about COVID-19 infection (self-reported severity, psychological status after infection, symptoms and medications, etc.) and parameters of menstruation (changed or not, specific manifestations).The severity of COVID-19 was self-reported as scores from 1 to 10, with higher scores indicative of a more serious level.

Statistical analysis
The sample size was determined by the number of participants who finished the online survey.The baseline characteristics of participants were summarized as percentages for categorical variables and mean (standard deviation [SD]) for normally distributed continuous variables.The Chi-Squared test was used for categorical variables.Two sample t-test was used for normally distributed continuous variables and the Wilcoxon test for non-normally distributed continuous variables.To examine the association of SARS-CoV-2 infection with menstrual changes (yes/no, binary outcome), logistic regression models were used.Age and BMI were covariates in the adjusted model since age was unevenly distributed between the women with and without menstrual change, and BMI was a well-known factor causing menstrual irregularity.Restricted cubic spline (RCS) modelling was further performed to visually assess the association of age and SARS-CoV-2 infection severity with menstrual change.A two-sided test of a p value less than .05was considered significant.All analyses were completed by R version 4.0.2(R Foundation for Statistical Computing).

Results
A total of 1016 survey takers were included in this study.The characteristics of all participants were shown in Table 1.The mean age of the participants was 33.08 ± 7.21 years old, and the mean BMI was 21.93 ± 2.98.A total of 88.3% (897/1016) of the participants were of Han ethnicity, 71.2% (723/1016) of the women got married, and 87.4% (675 colleges and 213 colleges above) of the women had a college degree or higher.
As shown in Figure 1, 530 (52.2%) participants reported menstruation change after SARS-CoV-2 infection.The most common menstrual abnormalities included changes in the menstrual cycle, changes in menstruation flow, and changes in the menstrual period, which were reported by 348, 243 and 161 participants, respectively.
Participants were divided into two groups based on whether has menstrual change: menstrual change group (n ¼ 530) and no menstrual change group (n ¼ 486).The basal characteristics of the two groups were compared and shown in Table 2. Compared with the no menstrual change group, participants in the menstrual change group were significantly younger (32.55 ± 7.00 vs. 33.67 ± 7.39, p ¼ .013).Other characteristics in terms of BMI, race, marriage status, education, blood type, and medical history, were not significantly different between participants with or without menstruation changes (p > .05).We further explored the possible factors related to menstrual changes.In general, the menstrual change group have a more serious self-reported severity of COVID-19, more severe symptoms, less medication and more mental problems than those in the no menstrual change group.32.1% (165/530) participants in the menstrual change group reported a severity score � 6, while 21.2% (103/486) in the no menstrual change group with a severity score � 6, which was justified with RCS modelling showed in Figure 2. Significantly more participants had one or more symptoms of COVID-19, such as fever, frag, headache, pain and cough, compared with those in the no menstrual change group, however, fewer people take medicine (8.1% vs. 14.2%, p ¼ .004).Participants in the menstrual change group had a higher percentage of mental problems, such as nervous (22.6% vs. 17.3%, p ¼ .009),anxiety (34.9% vs. 24.5%,p < .001),depression (14.7% vs. 8.2%, p ¼ .003)and fear (10.8% vs. 6.4%, p ¼ .011),compared with those in the no menstrual change group (Table 3).As shown in Figure 2, age and severity were significantly associated with the menstrual changes (Figure 2).
At last, we assessed the possible factors related to menstruation cycle change.The age was significantly related to the menstruation cycle change, and the younger participant was more likely to menstruation cycle change, especially the delayed cycle.Other characteristics were not significantly different between participants with or without menstruation cycle changes (Supplemental Table 1)

Discussion
We conducted an online survey about the association between SARS-CoV-2 infection and menstruation based on the China population with the largest sample size in terms of SARS-CoV-2 infected population.The results indicated that COVID-19 with SARS-CoV-2 infection was associated with menstruation abnormal, with changed menstruation cycles, menstruation flow and menstruation duration following SARS-CoV-2 infection.
In this study, up to 52.2% (530/1016) of the SARS-CoV-2 infected participants reported changes in menstruation, which was higher than the 16% reported by Khan et al. [7] The most common menstrual disorders were changes in the menstrual cycle, menstrual period  and menstrual flow.Consistent with our results, some studies also revealed that COVID-19 could affect the female menstrual cycle [9,10], and evaluated the association between COVID-19-related mental health and menstruation changes [9].Of course, there was a study that suggested that the menstrual cycle and regularity do not change after adjusting confounding factors [8].One possible explanation for menstrual changes was that menstruation was influenced by mental health [11].Many studies have focused on mental health during COVID-19 pandemic [12].Two studies showed that 52.2-62.9%,58.1-63.6% and 24.9-58.6% of the study population experienced moderate to severe levels of depression, anxiety and stress, respectively [13,14].One cross-sectional study indicated that COVID-19-related high stress is associated with significant changes in the length of the menstrual cycle, the duration of the menstrual period and increased intermenstrual spotting compared with pre-infection themselves [9].Similarly, our study found mental health (nervousness, anxiety, depression, fear, etc.) was significantly associated with menstrual changes.Recently, studies have reported that the increased prevalence of irregular menstrual cycles was not related to COVID-19, but rather to the severity of anxiety, depression and/or stress [10,[15][16][17].
Besides, SARS-CoV-2 infection may affect endocrine glands (including ovary, thyroid) through a variety of pathways, including direct effects, immune response mediated indirect damage and/or inflammation-mediated abnormal activation of Hypothalamic-pituitaryovarian (HPO) axis [18,19].Endocrine disorders theoretically lead to delayed ovulation or anovulation, which manifests as menstrual changes or sex hormone changes.Li et al. reported a lighter menstruation flow or prolonged menstrual cycle, and the menstrual changes might be the result of transient changes in sex hormones caused by suppression of ovarian function [6].In contrast, another study showed that the COVID-19 pandemic did not result in population-level changes in ovulation and menstruation among women who used a mobile app to track menstrual cycles and predict ovulation [16].
In addition to severity and mental health problems, we found that participants' age was associated with menstrual changes for the first time.Participants with menstrual changes were younger than that of women without menstrual changes.It was speculated that the HPO axis in the younger individual was less mature and more susceptible to COVID-19 pandemic-related mental problems [20].When menstrual cycles, the most common menstrual abnormality, was further analyzed, age was still found to be significantly different between populations with or without menstrual changes, suggesting that age is the main factor for menstrual changes following SARS-CoV-2 infection.
Our study has some limitations.First, as it was an online questionnaire, the menstrual changes were selfassessed and self-reported with an objective.Second, there one inevitably subjected to participant bias, as some individuals had more access to the network and were interested in filling out the questionnaire, while others did not have access to this study or were unwilling to participate in this survey for various reasons.Third, the follow-up period for this questionnaire was not long enough, so there were potential menstrual abnormalities that may not have been recorded or lost.

Conclusion
The present study found that SARS-CoV-2 infection/COVID-19 was associated with the menstrual changes in terms of menstruation cycle length, menstruation flow and menstruation length.Age, severity and mood were related with the menstruation changes.

Figure 1 .
Figure 1.The association of age and SARS-CoV-2 infection severity with menstrual change using restricted cubic spline (RCS) modeling.

Figure 2 .
Figure 2. The distribution of different types of menstrual abnormalities in the participants.

Table 1 .
Basal characteristics of study participants.

Table 2 .
Comparison of variables between the two groups.

Table 3 .
Comparison of severity of COVID-19 and mental health between the two groups.