Introduction
Parenting stress is stress that occurs when the parenting demands from the child exceed the parenting resources of the parents [Reference Abidin1]. Parenting stress can be broadly classified into stress related to parent and child factors. Increased parenting stress can lead to (1) increased risk of child maltreatment [Reference Rodriguez and Green2, Reference Rodriguez and Richardson3], (2) poor parenting behavior [Reference Gerdes, Hoza, Arnold, Pelham, Swanson and Wigal4], (3) lower quality of life for parents [Reference Cho and Hong5], (4) worse communication within the family [Reference Ponnet, Wouters, Mortelmans, Pasteels, De Backer and Van Leeuwen6], and (5) increased risk of emotional and behavioral problems in the child [Reference Bakoula, Kolaitis, Veltsista, Gika and Chrousos7]. Therefore, increased parental stress could be a significant public health concern.
One factor that potentially increases parenting stress is cesarean section. The number of cesarean sections continues to grow worldwide [Reference Betran, Ye, Moller, Zhang, Gulmezoglu and Torloni8], and a large observational study has reported increased parenting stress associated with cesarean sections [Reference Chen, Lai, Hwang, Huang, Chou and Chien9]. Although the actual mechanism behind the association is not known, the prolonged physical pain resulting from a cesarean section may have some involvement. Compared with vaginal delivery, cesarean section is associated with higher pain even years after delivery [Reference Kainu, Sarvela, Tiippana, Halmesmaki and Korttila10, Reference Li, Liabsuetrakul, Stray-Pedersen, Li, Guo and Qin11], and this pain may reduce the mother’s parenting resources available to cope with the demands of childcare. Childhood illness may also have some involvement. It has been reported that cesarean sections are associated with childhood asthma, obesity [Reference Sandall, Tribe, Avery, Mola, Visser and Homer12, Reference Slabuszewska-Jozwiak, Szymanski, Ciebiera, Sarecka-Hujar and Jakiel13], and stress-related disorders [Reference Li, Sjolander, Song, Cnattingius, Fang and Yang14], which may make a child more demanding. However, the relationship between cesarean section and parenting stress is still not well understood, nor whether this relationship can be attributed to the mother herself, the child, or both.
In this study, we sought to determine the relationship between cesarean delivery and parenting stress in the Japan Environment and Children’s Study (JECS), a large birth cohort study in Japan.
Methods
Study design and population
Participants were mothers enrolled in JECS, an ongoing nationwide government-funded birth cohort study examining the impact of various environmental factors on children’s health and development. The design and baseline characteristics of the JECS have been reported in detail elsewhere [Reference Kawamoto, Nitta, Murata, Toda, Tsukamoto and Hasegawa15, Reference Michikawa, Nitta, Nakayama, Yamazaki, Isobe and Tamura16]. Briefly, pregnant women were enrolled between January 2011 and March 2014 at public facilities, such as health centers and obstetrics and gynecology departments, from 15 regional centers (in rural and urban locations) across Japan via face-to-face recruitment. Follow-up took place during mid/late pregnancy, at childbirth, and at 1.5, 2.5, and 3.5 years postpartum. Data were collected from the medical record transcriptions by physicians, midwives/nurses, and/or research coordinators and via self-report questionnaires distributed to the participants by hand at the cooperating health care providers during pregnancy and by post after childbirth.
This study analyzed the jecs-qa-20210401 dataset, which was first released in April 2021 and completed in February 2022. The dataset contains data on 103,057 pregnancies. In this study, 5,647 pregnancies were excluded due to multiple registrations (second or third registration of the same mother), 949 due to multiple births (twins or more), and 3,562 due to miscarriages or stillbirths. Among the remaining 92,941 unique mothers, an additional 532 were excluded due to dropout or missing data on mode of delivery, and another 27,174 were excluded due to dropout or missing data on parenting stress. This left 65,235 mothers for the final analysis (Figure 1).
Figure 1. Participant flow diagram.
All procedures contributing to this work complied with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. The JECS protocol was reviewed and approved by the Ministry of the Environment’s Institutional Review Board on Epidemiological Studies (100910001) and the ethics committees of all participating institutions. Written informed consent was obtained from all participants. The protocol of this study was also approved by the Ethics Committee of the University of Toyama (Protocol number R2022091).
Measures
Primary exposure
Mode of delivery (cesarean section or vaginal delivery), obtained from the medical record transcriptions, was used as the primary exposure variable.
Outcomes
Parenting stress was assessed on three occasions, at 1.5, 2.5, and 3.5 years postpartum, using the Japanese 19-item version of the Parenting Stress Index Short Form (J-PSI-SF) [Reference Araki, Kanemastu, Yokosawa, Arayashiki, Aizumi and Hujishima17]. This instrument was developed to evaluate postpartum parenting stress based on the 78-item PSI [Reference Narama, Kanematsu, Araki, Maru, Nakamura and Takeda18], which had itself originated from Abidin’s 101-item PSI [Reference Abidin1, Reference Kanematsu, Araki, Narama, Shirahata, Maru and Arayashiki19]. The J-PSI-SF has good internal consistency (Cronbach α = 0.87), test–retest consistency over a 1-year interval (r = 0.73), and a three-factor structure composed of difficult child, parental distress, and spouse factors [Reference Hatakeyama, Matsumura, Tsuchida, Inadera and Group20] (Supplementary Table S1).
The difficult child factor is defined as stress from the child’s temperament or behavior and consists of items 3, 4, 6, 8, 9, 10, and 11, including “10. My child imposes demands on me more than most children,” “9. My child is easily upset by small things,” and “6. My child cries or fusses rather often.”
The parental distress factor is defined as the stress felt by the parent while raising the child and consists of items 1, 2, 12, 13, 14, 17, 18, and 19, including “19. I am unable to enjoy things as I used to,” “12. I do not feel capable of handling things very well,” and “17. I feel alone without friends.”
The spouse factor is defined as stress in the relationship with the spouse/partner while raising the child and consists of two items, “16. There are more problems with my spouse by having a child” and “15. My spouse does not give me as much help as I expected.”
Mothers were asked to complete their response on a 5-point Likert scale (1 = strongly disagree, 2 = disagree, 3 = not sure, 4 = agree, and 5 = strongly agree), and items with reversed valence were scored by reversing scores 1 to 5. We calculated the subscale scores for the difficult child, parental distress, and spouse factors by summing the scores of corresponding items and the total J-PSI-SF score by summing all subscale scores and then used them as outcome variables.
Potential confounders
We selected potential confounders, defined as variables before and/or during pregnancy with a potential impact on both exposures and outcomes, as well as basic anthropometric and socioeconomic variables. These variables were maternal age during pregnancy, pre-pregnancy body mass index (BMI), parity, gestational age, pregnancy complication (e.g., hypertension, diabetes, and psychiatric disease), obstetrics complication (e.g., placenta previa, placental abruption, and intrauterine growth restriction), marital status, highest education level [Reference Matsumura, Hamazaki, Tsuchida, Kasamatsu, Inadera and Group21], employment status, annual household income, smoking status, alcohol intake, regular physical activity corresponding to a 10-min walk/day [Reference Craig, Marshall, Sjöström, Bauman, Booth and Ainsworth22, Reference Murase, Katsumura, Ueda, Inoue and Shimomitsu23], experience of a stressful event, negative attitude toward pregnancy, degree of emotional support [Reference Matsumura, Hamazaki, Tsuchida, Kasamatsu and Inadera24], and psychological distress assessed using the Kessler 6 (K6) questionnaire [Reference Furukawa, Kawakami, Saitoh, Ono, Nakane and Nakamura25–Reference Kessler, Andrews, Colpe, Hiripi, Mroczek and Normand27], and area of residence (regional center where participants were recruited). Variables were categorized according to standard medical practice or common practice in Japan (e.g., [Reference Matsumura, Hamazaki, Tsuchida and Inadera28]).
Statistical analysis
Descriptive characteristics are presented as frequencies and percentages. Multivariate linear regression analysis was performed to estimate crude and adjusted β coefficients and the standard errors of the means (SEMs). The exposure variables were the mode of delivery, timing of the J-PSI-SF assessment in the postpartum period (repeated measures), and the interaction between mode of delivery and timing of the J-PSI-SF assessment. Vaginal delivery and assessment at 1.5 years were used as the reference. Outcome variables were each score derived from the J-PSI-SF. The forced entry method was used to include all the potential confounders and their interactions with assessment timing to adjust the model.
Data were analyzed using SAS version 9.4 software (SAS Institute Inc., Cary, North Carolina).
Additional analysis
For a more in-depth analysis, we repeated the regression analysis using each item score of the J-PSI-SF.
Results
In total, 65,235 mothers were analyzed; the mean age ± standard deviation (SD) was 31.4 ± 4.8 years, and the mean pre-pregnancy BMI ± SD was 21.1 ± 3.2. Table 1 shows the participants’ characteristics according to the mode of delivery. Among 65,235 mothers, 12,049 had a cesarean section and 53,186 had a vaginal delivery. Cesarean section varied from 14.1 to 24.9% according to area of residence.
Table 1. Characteristics of participants according to mode of delivery.
Abbreviation: K6, Kessler psychological distress scale.
Table 2 shows unstandardized crude and adjusted β coefficients (SEMs) for each J-PSI-SF score according to mode of delivery, timing of J-PSI-SF assessment, and their interaction. The J-PSI-SF total score was higher in the cesarean section group than in the vaginal delivery group (adjusted β = 0.24, SEM = 0.09). This increase was almost entirely due to an increase in the difficult child factor score (adjusted β = 0.18, SEM = 0.05) and not to the parental distress factor score (adjusted β = 0.07, SEM = 0.04) or spouse factor score (adjusted β = −0.01, SEM = 0.02). The total score was higher at 2.5 years postpartum (adjusted β = 0.57, SEM = 0.23) than at 1.5 years postpartum. This increase was mainly due to an increase in the parental distress factor score (adjusted β = 0.43, SEM = 0.12). The total score was somewhat lower at 3.5 years postpartum (adjusted β = −0.46, SEM = 0.26) than at 1.5 years postpartum, owing to the combination of a large decrease in the difficult child factor score (adjusted β = −0.54, SEM = 0.15) and a small increase in the parental distress factor score (adjusted β = 0.19, SEM = 0.13). No significant interaction was observed between cesarean section and timing of assessment.
Table 2. Unstandardized crude and adjusted β coefficients (SEMs) for each score of the Japanese 19-item version of the Parenting Stress Index Short Form according to mode of delivery and timing of assessment in the postpartum period.
Note: Boldface type indicates significance, defined as the 95% confidence interval not crossing the reference (=0.00). “—” represents reference. Others include Yes × 1.5 y, No × 1.5 y, No × 2.5 y, and No × 3.5 y.
Abbreviation: SEM, standard error of the mean.
a Adjusted for maternal age, body mass index, parity, gestational age, pregnancy complication, obstetric complication marital status, highest education level, employment status, annual household income, smoking status, alcohol intake, regular physical activity, experience of stressful event, negative attitude toward pregnancy, emotional social support, psychological distress, and area of residence.
Table 3 summarizes the results of the additional analysis. As in the main analysis, the additional analysis using each J-PSI-SF item revealed that cesarean section was associated with higher scores on items 3, 4, 6, 10, and 11 for the difficult child factor. Additionally, cesarean section was associated with higher scores only on item 18 for the parental distress factor and item 5, which does not belong to any factor. Again, no significant interaction was observed between cesarean section and timing of assessment.
Table 3. Unstandardized adjusted β coefficients (SEMs) a for each item of the Japanese 19-item version of the Parenting Stress Index Short Form according to mode of delivery and timing of assessment in the postpartum period.
Note: Boldface type indicates significance, defined as the 95% confidence interval not crossing the reference (=0.00). “—” represents reference. Others include Yes × 1.5 y, No × 1.5 y, No × 2.5 y, and No × 3.5 y.
Abbreviations: DC, difficult child; PD, parental distress; SEM, standard error of the mean; SP, spouse; UI, unused item not belonging to any factor.
a Adjusted for maternal age, body mass index, parity, gestational age, pregnancy complication, obstetric complication marital status, highest education level, employment status, annual household income, smoking status, alcohol intake, regular physical activity, experience of stressful event, negative attitude toward pregnancy, emotional social support, psychological distress, and area of residence.
Discussion
This study examined the relationship between cesarean section and parenting stress. The results consistently showed a slight, but significant, increase in J-PSI-SF total scores for the cesarean section group from as early as 1.5 years of age. This increase was primarily due to an increase in the J-PSI-SF difficult child factor score (i.e., stress from the child’s temperament or behavior), and not in the score for factors related to parental distress (i.e., stress felt by the mother during childrearing) or spouse (i.e., stress in the relationship with spouse while raising the child). The finding of increased parenting stress associated with a cesarean section is consistent with the results of a previous large cohort study [Reference Chen, Lai, Hwang, Huang, Chou and Chien9].
The J-PSI-SF difficult child factor score was higher for children delivered by cesarean section. One reason for this may be that allergic disease and obesity are more common in these children [Reference Sandall, Tribe, Avery, Mola, Visser and Homer12, Reference Slabuszewska-Jozwiak, Szymanski, Ciebiera, Sarecka-Hujar and Jakiel13]. Studies of parenting stress have consistently found that parenting stress is increased when a child has an autism spectrum disorder, allergy, or physical disease [Reference Kanematsu, Araki, Narama, Shirahata, Maru and Arayashiki19]. Our previous study also showed an increased prevalence of functional constipation in children born by cesarean section [Reference Nakamura, Matsumura, Ohnuma, Yoshida, Tsuchida and Hamazaki29], which also likely increases the parenting demands from the child.
In relation to the above, children born by cesarean section are known to exhibit an excessive stress response to acute psychological stressors even in adulthood [Reference Dinan, Kennedy, Morais, Murphy, Long-Smith and Moloney30]. It has been suggested that passage through the birth canal is critical in the development of the core stress system, namely, the hypothalamic–pituitary–adrenal axis, and bypassing this may have a negative impact on strong stress experiences [Reference Lagercrantz31]. It has also been reported that children born by cesarean sections have low diversity of gut microbiota, and such low diversity is related to psychiatric disorders [Reference Rieder, Wisniewski, Alderman and Campbell32]. Recent epidemiological studies have reported that the only factor associated with stress-related disorders after controlling for siblings is cesarean section [Reference Li, Sjolander, Song, Cnattingius, Fang and Yang14], and cesarean section was associated with neurodevelopmental disorders when not controlling for siblings [Reference Zhang, Brander, Mantel, Kuja-Halkola, Stephansson and Chang33]. Further research is needed to investigate the impact of cesarean section on psychiatric disorders, neurodevelopment disorders, and stress reactions in children, as well as allergy and obesity issues, all of which are highly likely to lead to a more demanding child.
When analyzed on an individual item basis, cesarean section was found to be associated with many of the items comprising the J-PSI-SF difficult child factor, consistent with our main results. More specifically, children born by cesarean section had worse scores on items for being too active, having difficulty concentrating, not pleasing their mother, being prone to crying and fussing, being demanding, and being attached to the mother. These responses are suggestive of attention deficit hyperactivity disorder, hyperarousal, separation anxiety, and being prone to illness. As noted in the introduction, the following pathway can be posited: (1) cesarean section; (2) neuropsychiatric and developmental disorders and other illnesses; and (3) increased J-PSI-SF difficult child factor scores. For the parental distress factor, on the other hand, the only significant association observed was between cesarean section and illness, aches, and pains, and there was no association with other items such as not enjoying being a parent, having less social support, or feeling unable to cope with things. This association between cesarean section and pain is consistent with previous studies [Reference Kainu, Sarvela, Tiippana, Halmesmaki and Korttila10, Reference Li, Liabsuetrakul, Stray-Pedersen, Li, Guo and Qin11], but this alone would not have led to a clear reduction in parenting resources, and thus was not associated with J-PSI-SF parental distress factor score as the umbrella factor.
Cesarean sections can be a life-saving procedure when medically indicated, but they are increasing worldwide [Reference Betran, Ye, Moller, Zhang, Gulmezoglu and Torloni8], and Japan is no exception [Reference Yuda34]. In particular, the number of procedures performed at the request of the mother is increasing [Reference Zhang, Liu, Meikle, Zheng, Sun and Li35]. Generally, it is known that cesarean sections not only increase maternal mortality and morbidity, but also cause allergic diseases and obesity in the child. Additionally, recent large epidemiological studies have shown that cesarean sections increase the risk of psychiatric disorders [Reference Li, Sjolander, Song, Cnattingius, Fang and Yang14]. Therefore, taken together with the results of this study, the decision to have a cesarean section should not be made lightly.
This study has the following strengths. First, we analyzed data from an ongoing nationwide birth cohort with a large sample exceeding 65,000 mothers who were recruited from both urban and rural areas between 2011 and 2014. Therefore, the sample can be considered to be representative of recent Japanese mothers. Second, assessments were performed three times, at 1.5, 2.5, and 3.5 years postpartum. This allowed us to obtain rich results. Third, we considered 16 potential confounders, so our estimates are likely reasonable.
This study also has some limitations. First, we derived data on the delivery mode from the medical record transcriptions, but we have no data on whether the cesarean section was elective (scheduled) or emergency. If we had distinguished between these, the results might have been slightly different, given that these differences in caesarian section are reported to affect the mental state of mothers [Reference Zanardo, Giliberti, Giliberti, Volpe, Straface and Greco36] and neurodevelopmental disorders when not controlling for siblings [Reference Zhang, Brander, Mantel, Kuja-Halkola, Stephansson and Chang33]. Second, mothers with high parenting stress may have dropped out of the cohort, possibly resulting in selection bias. Finally, the generalizability of the association found in this study must be examined in other settings outside Japan, where the J-PSI-SF has not yet been validated, and in other populations in addition to mothers.
In conclusion, this study found that cesarean section was associated with increased parenting stress, especially in terms of the difficult child factor, but not with the parental distress or spouse factor. In the case of cesarean section, particular attention should be paid to the mental health of both mother and child.
Supplementary Materials
To view supplementary material for this article, please visit https://doi.org/10.1192/j.eurpsy.2023.5.
Data Availability Statement
Data are unsuitable for public deposition due to ethical restrictions and the legal framework of Japan. It is prohibited by the Act on the Protection of Personal Information (Act No. 57 of 30 May 2003, amendment September 9, 2015) to publicly deposit the data containing personal information. Ethical Guidelines for Medical and Health Research Involving Human Subjects enforced by the Japanese Ministry of Education, Culture, Sports, Science and Technology and the Ministry of Health, Labour and Welfare also restrict the open sharing of the epidemiologic data. All inquiries about access to data should be sent to: [email protected]. The person responsible for handling inquiries sent to this e-mail address is Dr Shoji F. Nakayama, JECS Programme Office, National Institute for Environmental Studies.
Acknowledgments
We are grateful to the participants of the JECS and to all individuals involved in the data collection process.
Author Contributions
Conceptualization: K.M. and T.Y.; Data curation: The JECS Group; Formal analysis: K.M.; Funding acquisition: The JECS Group; Investigation: The JECS Group; Methodology: K.M. and T.H.; Project administration: H.I., The JECS; Resources: The JECS Group; Supervision: The JECS Group; Visualization: K.M., T.H., T.Y., A.T., and H.I.; Writing—original draft: K.M.; Writing—review & editing: T.H., T.Y., A.T., and H.I., The JECS Group.
Financial Support
The JECS was funded by the Ministry of the Environment, Japan (Grant number: N.A.). The funding source played no role in the study’s design, collection, analysis, or interpretation of data; in the writing of the report; or in the decision to submit this paper for publication. The findings and conclusions of this article are solely the responsibility of the authors and do not represent the official views of the above government agency.
Conflicts of Interest
The authors declare none.
A. Appendix
Members of the JECS Group as of 2022: Michihiro Kamijima (Principal Investigator, Nagoya City University, Nagoya, Japan), Shin Yamazaki (National Institute for Environmental Studies, Tsukuba, Japan), Yukihiro Ohya (National Center for Child Health and Development, Tokyo, Japan), Reiko Kishi (Hokkaido University, Sapporo, Japan), Nobuo Yaegashi (Tohoku University, Sendai, Japan), Koichi Hashimoto (Fukushima Medical University, Fukushima, Japan), Chisato Mori (Chiba University, Chiba, Japan), Shuichi Ito (Yokohama City University, Yokohama, Japan), Zentaro Yamagata (University of Yamanashi, Chuo, Japan), Hidekuni Inadera (University of Toyama, Toyama, Japan), Takeo Nakayama (Kyoto University, Kyoto, Japan), Tomotaka Sobue (Osaka University, Suita, Japan), Masayuki Shima (Hyogo Medical University, Nishinomiya, Japan), Hiroshige Nakamura (Tottori University, Yonago, Japan), Narufumi Suganuma (Kochi University, Nankoku, Japan), Koichi Kusuhara (University of Occupational and Environmental Health, Kitakyushu, Japan), and Takahiko Katoh (Kumamoto University, Kumamoto, Japan).
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