Suicide has become the second leading cause of death among young people aged 15 to 29 (1, 2), with a rate of 4.57 per 100,000 (3). It is well recognized that suicidal ideation (SI) is an important predictor of suicide death (4). A meta-analysis showed that the prevalence of SI was 28% in adolescents up to 25 years (5). Factors such as negative life experiences (e.g., childhood abuse, bullying), unhealthy behaviors (e.g., smoking, alcohol abuse, poor parental relationships), psychological factors (e.g., low emotional support, low self-esteem, impulsivity), and physical illnesses (e.g., HIV, insomnia, chronic illness) could contribute to the occurrence of SI (6–16). However, there is a significant gender difference in suicide deaths between men and women; the suicide death rate of men is higher than that of women (17).

After the coronavirus disease 2019 (COVID-19) pandemic was announced by WHO on March 11, 2020 (18), there were over 304 million confirmed cases and over 5.4 million deaths until January 9, 2022 (19). Each government has responded quickly and has adopted necessary positive measures after the pandemic, including advocating quarantine at home, wearing masks, social distancing, etc., (20, 21). However, subsequent repeated home isolation policy might have a profound impact on people's mental health. The prevalence of mental health problems has become much higher during the COVID-19 pandemic lockdown period, including suicide issues (22–26). However, the influence of COVID-19 on suicidal ideation and the gender differences in adolescents have not been well-studied.

We conducted a cross-sectional online survey to explore the prevalence of SI during the COVID-19 pandemic lockdown period in Chinese adolescents and to explore gender-specific correlated factors for SI.

The sample population of our survey was randomly distributed in five counties in two cities, including the 8th grades. Finally, there were 5,175 available questionnaires. The characteristics of participants are displayed in Table 1. There were 2,673 (51.7%) males and 2,502 (48.3%) females. Among these, 3,813 (73.7%) were from rural and 1,362 (26.3%) were from urban. The age range was 9–19 years old and the mean (SD) of participants' age was 13.38 (1.56%). Most of the participants were junior high school students (60.2%), others were in primary school (25.9%), and senior high school (13.9%). There were 3,842 (74.2%) participants who lived with parents, 197 (3.8%) lived only with their father, and 816 (15.8%) lived only with their mother. Most of the participants have at least one sibling (78.9%). Besides, 1,346 (26%) felt depressed and 1,224 (23.7%) felt anxious. Among 5,175 students, 155 (3%) had suicidal ideation during the COVID-19 pandemic lockdown. Among 2,673 male and 2,502 female participants, there are 64 (2.39%) males with suicidal ideation, 2,609 (97.61%) males without suicidal ideation, 91 (3.64%) females with suicidal ideation, and 2,411 (96.36%) females without suicidal ideation. The characteristics of 5,175 participants by sex and suicidal ideation were displayed in Table 2.

The prevalence of suicidal ideation during the COVID-19 pandemic lockdown of all the participants was 3%. The prevalence of suicidal ideation in female participants (3.64 %) was higher than that in males (2.39%) (χ² = 6.87, P = 0.009). There was no significant difference in the prevalence of suicidal ideation between adolescents in different grades (χ² = 2.33, P = 0.312), one-child family structure (χ² = 0.06, P = 0.801), and residence areas (χ² = 0.61, P = 0.436).

The correlations between the related factors and the suicidal ideation during the COVID-19 pandemic lockdown were analyzed by univariate logistic regression (Table 3). Demographic characteristics (age), specific status during COVID-19 pandemic lockdown (feeling depressed, feeling anxious, insomnia and quarreling with parents), parenting styles (father's emotional warmth, father's punishment, father's over-interference, father's rejection, father's overprotection, mother's emotional warmth, mother's punishment, mother's over-interference and overprotection, and mother's rejection), and a lifetime of severe traumatic events (being bullied at school, being attacked by family/teachers/strangers, previous suicidal attempt history, previous suicide attempt history, and having emptiness inside) were associated with suicidal ideation in the participants during COVID-19 pandemic lockdown. Sex-specific results are in Table 3.

The stepwise logistic regression results for suicidal ideation were shown in Table 4. Quarreling with parents (OR = 9.73, 95% CI: 5.38–17.59), insomnia (OR = 5.28, 95% CI: 2.81–9.93), previous suicide attempt history (OR = 3.68, 95% CI: 1.69–8.03), previous suicidal ideation history (OR = 2.81, 95% CI: 1.30–6.06), and feeling depressed (OR = 2.26, 95% CI: 1.22–4.18) were associated with the SI during COVID-19 lockdown in male participants. In female participants, having emptiness inside (OR = 4.39, 95% CI: 2.19–8.79), quarreling with parents (OR = 3.72, 95% CI: 2.16–6.41), insomnia (OR = 3.28, 95% CI: 1.85–5.80), feeling anxious (OR = 2.62, 95% CI: 1.46–4.70), previous suicide attempt history (OR = 2.53, 95% CI: 1.41–4.54), being bullied at school (OR = 2.03, 95% CI: 1.15–3.06), being attacked by family/teachers/strangers (OR = 1.84, 95% CI: 1.01–3.33), being the only child (OR = 0.48, 95% CI: 0.24–0.98), and father's emotional warmth (OR = 0.38, 0.20–0.72) were associated with SI during COVID-19 lockdown.

The prevalence of SI during the COVID-19 pandemic lockdown was 3% in this sample of Chinese children and adolescents. Females were more likely to have reported SI than males. Female adolescents, with emptiness from father's emotional warmth to the family, were at much higher risk of having SI during COVID-19 lockdown, while the male adolescents with feelings of depression, insomnia, quarreling with parents during COVID-19, suicidal ideation, or attempt history might associate these with suicidal ideation during COVID-19.

We found that there was an obvious sex difference in suicidal ideation in adolescents, which is consistent with other studies (31). Males and females had common factors for SI. However, there were sex-specific factors associated with SI. Feeling depressed was associated with SI in males rather than in females. Feeling anxious was only associated with SI in females rather than in males. Therefore, given the sex difference, we should pay more attention to different symptomatic manifestations in boys and girls to prevent the occurrence of suicidal behaviors during natural disasters like the COVID-19 pandemic. However, only a few studies are exploring the relationship between mood disorders and suicidal ideation by sexes, and more future studies are needed.

The prevalence of suicidal ideation (3%) in adolescents was relatively low compared with that in other studies (12.7%) (10). This may be similar to the result of other studies indicating that the suicide rate in adolescents during the COVID-19 pandemic was not raised, and Tanaka's study showed that the suicide rate declined by 14% in the first 5 months in Japan (22, 32). There are several possible reasons for that. First, home isolation may reduce the chance of negative interpersonal communication with their peers, which may improve the mental health of adolescents (33). Second, according to the results of this study, some adolescents had poor relationships with parents (such as quarreling with parents). This study was conducted when the participants just returned to school and spent more time at school, which might have reduced the conflicts with parents. Third, it is possible that the COVID-19 pandemic lockdown did not have a dramatic impact on suicidal ideation (23–26). Other studies also showed that there was no obvious change of suicidal ideation in adolescents during the COVID-19 pandemic lockdown (32).

Some specific behaviors (quarreling with parents, insomnia, etc.) during COVID-19 may be associated with the onset of SI in adolescents during COVID-19 pandemic lockdown and had negative impacts on adolescents' mental health. Because of the COVID-19 pandemic, it was difficult to seek professional help. In this context, telepsychiatry is a promising way of mental health service delivery to address the issues to enhance the children and youth's ability to cope with stress, alleviate depressed mood, and reduce their risk of suicide (34, 35). Given the huge gender difference for suicidal ideation in adolescents, independent predictive models based on gender may be necessary to identify the high-risk individuals for suicidal ideation in adolescents. A finding from our result is that a good fatherly emotional warmth may be an important factor to prevent the occurrence of suicidal ideation in female adolescents.

A suicide prevention system, based on the school-family-community joint mechanism for children and adolescents, should be built (36). For the entire society, the suicide prediction and intervention systems need to be established to identify the high-risk individuals through the system and intervene promptly. In addition, a developmentally-sequenced upstream suicide prevention approach is extremely important (36). Firstly, the parents and the schools should try to eliminate risk factors of suicide such as school bullying and parental abuse. Secondly, we should also pay more attention to strengthening the psychological and behavioral education in children and adolescents to improve mental health, and in minimizing the impact of possible negative events.

Globally, we are still suffering from the COVID-19 pandemic (19) and Murray said that by March 2022, more than 50% of people in the world will be infected with Omicron, and 80–90% of them will be asymptomatic (37). At that time, the global immunization level will be at the highest level in history due to continuous vaccination and because of the immunity caused by virus infection. In a few weeks or months, the level of COVID-19 spread will decrease (37). Each government should publicize epidemic-related policies and promote scientific knowledge on COVID-19 to reduce public panic, especially for adolescents, and reduce the negative impact of rumors (which may increase the risk of suicide), scientifically and correctly arrange online classes, and control the influential impact of home isolation on adolescents (38, 39). In the post-pandemic era, the beginning of normal life is also an important period to deal with its sequelae and prevent the potential increase in the suicide rate (23). Changes in the financial conditions of the family (e.g., being laid off), changes in adolescents' social relationships due to home isolation, and discomfort after returning to school may also worsen the mental health of adolescents (40–42). During this period, the school can play an important role in maintaining and improving mental health and preventing suicide in students (43). Adolescents spend more time at school than with their families. Therefore, the school-related department needs to adjust the adolescents' mindset and learning habits to mitigate the adverse impact of the COVID-19 pandemic.

There were several limitations in this study. First, suicidal ideation and exposures were collected by self-report in this cross-sectional study. Therefore, recall and reporting biases are possible. Second, there were limited correlated factors collected in this study, and some other exposures, such as the history of mental disorders and biological factors, were not collected (44). Third, the participants in this study were only sampled from two cities in Shandong Province, China. Furthermore, because of the relatively low response rate (56%), this sample may not be representative of the Chinese adolescent population. Finally, in this cross-sectional study, the causal relationships between exposures and suicidal ideation could not be inferred. Cohort studies were needed.

In our research, a specific status during COVID-19 pandemic lockdown, lifetime severe traumatic events, and parental rearing styles could influence the prevalence of suicidal ideation among adolescents, and there was also a considerable gender difference. At present, there are few studies on the suicide behavior of adolescents during and after the COVID-19 pandemic. Although most of the regions in China have lifted the lockdown measures and returned to normal life, some cities may have to re-implement restrictive measures because of the recurrence of COVID-19. Many countries are still suffering from COVID-19. Therefore, our study generated new knowledge for informing the public health policies and raising awareness about adolescent mental health.

Female adolescents, with a feeling of emptiness from their father's emotional warmth to the family, were at much higher risk of having SI during COVID-19 lockdown. Identifying the predictors of suicide behaviors of different genders is conducive to preventing suicide and is a more effective identification of suicide high-risk groups. Therefore, we have to specify a suicide prevention policy and interventions for adolescents in the pandemic crisis based on gender gaps.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Research Ethics Committee in Jining Medical University. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

DL, JW, and YL contributed to the study design. LL, DL, SY, and JZhu did the online survey, data collection, and logical check. MC, JZha„ YL, and DL analyzed the data. JZhu, BL, FH, and LL wrote this manuscript. DL, YL, and JW revised the manuscript and did the English revision. All authors reviewed and approved the manuscript.

This study was funded by the Research Fund for Lin He's Academician Workstation of New Medicine and Clinical Translation in Jining Medical University to JZhu (Grant Number: JYHL2019MS05, JYHL2021MS14), Taishan Scholars Project of Shandong Province (tsqn201909145), and Key Research and Development Plan of Jining (Grant Number: 2019SMNS033) to YL, and Innovative Training Program for College Students in Jining Medical University to DL (Grant Number: cx2020009).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict ofinterest.

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