|Year : 2019 | Volume
| Issue : 2 | Page : 103-111
Maternal mental health and its influence on infant growth and development: A systematic review of observational studies in South and East Asia
Shubhashree Venkatesh, J Vindhya, Anita Nath
Public Health Foundation of India, Indian Institute of Public Health, Hyderabad-Bangalore Campus, Bengaluru, Karnataka, India
|Date of Web Publication||4-Jun-2019|
Dr. Anita Nath
Public Health Foundation of India, Indian Institute of Public Health, Hyderabad-Bangalore Campus, 1st Cross Magadi Road, Bengaluru - 560 023, Karnataka
Source of Support: None, Conflict of Interest: None
Maternal mental stress during pregnancy is an important public health concern. There is strong evidence from the Western world to support the presence of a significant association between maternal stress in pregnancy and adverse outcomes in the offspring. There are fewer studies from the South and East regions of Asia. The search was conducted according to the PRISMA criteria. Databases which included NCBI PubMed, Scopus, and Embase were used to search for relevant studies according to the eligibility criteria. Most of the studies have shown a significant relation between stress, depression, and anxiety during various stages of pregnancy with delayed mental, motor, and behavioral development of the child. Although studies from the region show a significant relation between various stress factors during pregnancy and child development, more such studies are needed, especially those using potential biomarkers as indicators of pregnancy-related stress.
Keywords: Child development, maternal depression, maternal mental stress, Southeast Asia
|How to cite this article:|
Venkatesh S, Vindhya J, Nath A. Maternal mental health and its influence on infant growth and development: A systematic review of observational studies in South and East Asia. Indian J Health Sci Biomed Res 2019;12:103-11
|How to cite this URL:|
Venkatesh S, Vindhya J, Nath A. Maternal mental health and its influence on infant growth and development: A systematic review of observational studies in South and East Asia. Indian J Health Sci Biomed Res [serial online] 2019 [cited 2020 Jan 25];12:103-11. Available from: http://www.ijournalhs.org/text.asp?2019/12/2/103/259646
| Introduction|| |
There is supporting evidence that many physical and mental health conditions in an individual arise due to adverse early life experiences, particularly in relation to prenatal and childhood environment. There exists a strong background to investigate the relationship between early life adversities such as exposure to maternal mental stress during pregnancy and neurodevelopmental and health outcomes in later life, including behavioral, emotional, and cognitive psychopathology and chronic metabolic diseases. While a lot of importance has been historically directed toward postnatal depression, there is now an increasing recognition that common mental disorders during pregnancy which include depression, anxiety, and self-perceived stress could impose an effect on pregnancy outcomes and offspring development. Animal studies also demonstrate the presence of this kind of an association.,
| Etiology and Prevalence of Maternal Depression|| |
A few physiological pathways are proposed to mediate this relationship type such as altered placental function, epigenetic changes, and stress reactivity. Anxious mothers may exhibit physiological changes such as altered uterine flow and consequently neurotransmitters such as norepinephrine that may influence the development of the fetus., There also exists a wide belief that increased levels of stress during pregnancy accelerate the secretion of cortisol to the extent to which it becomes neurotoxic to the developing fetal brain, which likely results in adverse development during infancy and childhood.
The prevalence of antenatal depression ranges from 19% to 25% in low- and middle-income countries unlike the range of prevalence from 7% to 15% in high-income countries., There are ample studies which have been conducted in the Western world to understand the association between maternal stress in pregnancy and adverse outcomes in the offspring. These studies range from understanding the mediating pathway in animals and humans to epidemiological studies on the burden and associated risk factors of mental stress in pregnancy and its outcome on maternal and child health. However, there are limited data from Southeast Asia, given the major difference in social, economic, and cultural environment in contrast to the developed world, and hence, the findings could vary., While there is well-documented research on postpartum depression, studies related to mental health issues during pregnancy are in its early stage. Therefore, this review was conducted with the aim to understand if maternal mental stress in the form of common mental disorders and maternal cortisol levels, serving as a potential biomarker for stress, influence infant growth and development by means of a review of studies conducted in countries that comprise South and East Asia.
| Materials and Methods|| |
The PRISMA criteria, a widely used search strategy for systematic review of observational studies, were employed to include relevant literature. The online databases that were used to extract literature included NCBI PubMed, Embase, and Scopus.
Eligibility criteria for inclusion of studies were as follows:
- Publications over the past 15 years before November 1, 2017
- English language
- Full-text articles
- Observational studies in human participants
- Ongoing study protocols
- Studies done in South and East Asia.
Search terms used are shown in [Table 1].
The exposure variable comprised maternal mental health in the form of depression, anxiety, and self-perceived stress, and the outcome variable included infant growth and development. While “growth” denotes a net increase in the size or mass of tissues, “development” specifies maturation of functions in the form of skill acquisition for optimal functioning.
| Results|| |
A total of 463 abstracts of studies that had been conducted between 2002 and 2017 were retrieved. The steps toward the final inclusion of the 13 studies (11 published and 2 ongoing published protocols) are shown in [Figure 1]. [Table 2] gives a brief presentation of the selected studies while the abbreviations that are used throughout the text are explained in [Table 3].
Mental distress and infant development
While Otake et al. did not find any significant association between antenatal depression and Bayley Scales of Infant Development (BSID) scores in terms of Mental Development Index (MDI) and Psychomotor Development Index, they did observe a significant relationship between antenatal depression and shorter gestational age which in turn was significantly related to developmental delay in infant cognitive function. Hence, gestational age was an important confounder in this association. Tran et al. and Lin et al.,, however, in one of their statistical model pathways found a direct association between high Edinburgh Postnatal Depression Scale (EPDS) scores in early pregnancy and low BSID scores for motor development at 6 months and 2–3 years of age. In another model pathway, the presence of a common mental disorder directly decreased the infant outcome by 7.13 points (95% confidence interval [CI]: 3.13–11.13). Some of the potential confounders that were identified in this study were parity and breastfeeding. While infants of primiparous women had lower BSID scores, infants of mothers who were reported to have sufficient breast milk scored higher. Bhang et al. also observed a significant association between presence maternal stress, depression, and lower scores on the MDI. However, there was no association with development of motor, communication, social, and problem-solving skills. Likewise, Zhu et al. also found that the MDI scores of the infants of mothers with prenatal exposure to stressful life events averaged seven points (95% CI: 3.23–10.73 points) lesser than infants who were not exposed. The association of prenatal stressful life events and infant development can be evident early in neonatal life according to the study by Su et al. wherein newborns with maternal life stressors' exposure had significantly lower scores on neonatal behavioral neurological assessment.
Mental distress and undernutrition
Rahman et al. and Nasreen et al. observed that mental distress in pregnancy was significantly associated with an increased risk of undernutrition (underweight and stunting) in infants, even after controlling for all known confounding factors.
Mental distress and infant temperament
Bhat et al. did not observe any significant association between maternal prenatal psychological distress and maternal report of difficult temperament in infants although infant salivary cortisol was significantly higher in infants with higher intensity scores. A significant association between maternal stress reported as Global Severity Index and decreased toddlers' adaptive and social behavior development was observed by Lin et al. Park et al. also reported that severe maternal stress experienced during pregnancy was highly associated with both internalizing problems and externalizing problems among school-aged children. A less optimal behavioral response among children whose mothers experience stress in early pregnancy was observed by Zhu et al.
There is an ongoing prospective cohort study that is being conducted among 2612 eligible pregnant women who have been registered for antenatal care at selected public-sector hospitals in Bengaluru. The study aims to prospectively assess the association of maternal psychological distress and cortisol level with motor and cognitive development of the infant.
Another such study is ongoing among labor migrants and refugees living on the Thai–Myanmar border in a cohort of 627 women, to understand the association between maternal depression and obstetrical and infant outcomes.
| Discussion|| |
Most of the studies reported the existence of a significant relationship between maternal stress, depression, and lower scores on mental development,, which is evident from literature wherein self-reported maternal mental health conditions have been associated with delayed infant cognitive development., Offspring mental development could also be determined by the timing of prenatal exposure to maternal stress. Exposure to mental stress in early pregnancy was significantly associated with impaired cognitive development in these studies,, which has been corroborated by other studies,, while in the study by Su et al., exposure to stressful life events at any point of time during pregnancy was considered. The impairing effect of antenatal mental stress on motor development in infancy was observed in one study. While all these studies used self-reporting measurements to establish the presence of a mental morbidity, none of these have studied the mediating effect of cortisol which reflects the activity of the hypothalamic–pituitary–adrenal (HPA) axis and is observed to mediate the effects of prenatal maternal stress on the developing fetus., The independent effect of maternal psychological stress and cortisol on both cognitive and motor development of the infant will be analyzed in the ongoing prospective cohort study that is being conducted in South India. Cortisol is a stress-related neurohormone and is important for fetal maturation and birth process, even a slight variation in this hormone early during pregnancy can generate a cascade of events resulting in a change in the fetal stress response system which eventually impacts growth and development.
All the studies observed a significant association between antenatal mental distress and undernutrition in infancy., This could be attributed to various factors such as poor care-seeking behavior during the antenatal period which could also be influenced by other psychosocial factors such as lack of family support and interpersonal conflicts.
Social behavior of the offspring can be influenced by prenatal depression resulting in deviations from the acceptable level as reported from most of the studies.,, This finding is also supported by studies done in other countries which also observed the existence of this kind of a strong association.,, However, only Bhat et al. measured the infant salivary cortisol levels which were higher in infants with high intensity scores; however, there was no significant association between maternal psychological distress and infant outcome.
Strengths and limitations
Measures of exposure variables
All the studies used depression and stress as their exposure variable. Different scales were used to measure depression across these studies. EPDS was used in four studies,,, and is a widely used reliable instrument for screening depression in the postnatal period but has shown high reliability when used prenatally. The use of EPDS had been translated into the local language and validated for measuring prenatal depression in the countries where these four studies were done. The EPDS cutoff scores for detecting the probability of depression varied across the four studies. Tran et al. used the EPDS-Vietnam Validation in which scores ≥4 detect clinically significant symptoms with a sensitivity of 70% and specificity of 73%. Soe et al. did not use a specific cutoff score but analyzed the changes in EPDS scores throughout pregnancy and postpartum. Otake et al. used a standardized cutoff score of 8/9 which is applicable to Japanese women.
The General Health Questionnaire-28 which is a 28-item questionnaire used in the study by Bhat et al. to assess prenatal depression has also been validated for screening with a sensitivity of 82% and a specificity of 85%. Bhang et al. used the Center for Epidemiologic Studies-Depression Scale which measures general stress rather than pregnancy-specific stress; however, it has been shown to be a reliable and valid tool to measure prenatal depression. Lin et al. and Su et al. assessed the presence of mental distress by analyzing exposure to stressful life events using the Symptom Checklist-90-Revised Scale and Life-Event-Stress Scale which have been well validated and used in China. Park et al. did not use any measuring scale for psychological distress, instead they inquired for any personal or social situations that may have caused severe physiological and psychological stress during pregnancy.
Measures of outcome variables
Five studies used infant development as their outcome variable. BSID-II and its other version BSID Motor Scale was the most commonly used scale in four of the studies and is the most reliable scale for infant motor and cognitive development.,,, The use of BSID had been translated into the local language, pilot tested, and validated for use in the corresponding study area in all the studies. Lin et al. used Gesell Development Scale to measure cognition. The scale, originally designed by Arnold Gesell in 1925, is now known as Gesell Developmental Observation-Revised, has been validated for use in children residing in the United States, and was revised again by Chinese scholars in 1994.
Some studies explored infant behavior and temperament as the outcome variable using Toddler Temperament Scale,, Korean-Ages and Stages Questionnaires, Korean-Child Behavior Checklist (K-CBCL),, 76-item Early Infancy Temperament Questionnaire, Neonatal Behavioral Assessment Scale, and CBCL, all of which are parent-reported questionnaires. The Toddler Temperament Scale measures the following four categories of temperament – mood adaptability, intensity, approach, and activity wherein the data generated from this questionnaire have shown a strong correlation with laboratory-based videotapes of the child's behavior. K-CBCL derived from CBCL designed by Achenbach in 1983 has shown a high inter-rater reliability and concurrent validity when used in South Korea. Cronbach's alpha using the CBCL scale ranged from 0.62 to 0.95 within the sample in the study which was done by Soe et al.
Two studies used infant undergrowth and stunting as the outcome variable – Nasreen used the appropriate WHO growth standard for assessment while Rahman et al. used weight-for-age z score of <−2 for underweight and length-for-age z score of <−2 for stunting. To strengthen evidence, in addition to self-reporting measures, objective measures of exposure outcomes were also assessed by Bhat et al., infant salivary cortisol; Soe et al., infant frontal activity; and Su et al., umbilical cord plasma stress-related hormones. Cortisol reactivity to an acute stressor is commonly used to measure the functioning of the HPA axis functioning which in turn influences infant development.
Risk of bias and confounding
The risk of bias due to confounding appears to have been addressed in all the studies by adjusting for all the possible known and relevant confounders. Bhang et al., 2016, however, in their study on the association between prenatal depression and infant development, did not measure postpartum mental health of the mother, which could also be a potential confounder. However, unlike in other studies, Bhang et al. measured and adjusted for exposure to heavy metals and oxidative stress which can adversely influence infant neurodevelopment. All the studies except for four were prospective cohort studies which eliminate the risk of recall bias. Park et al. interviewed mothers of third- and fourth-grade children, to probe for the presence of any kind of psychological distress that might have taken place during pregnancy, which could have been characterized by gross inadequacies in memory recall. The measuring scales that were used for the exposure and outcome variables were valid and reliable which minimized the risk posed by measurement. However, the parent reporting scales that were used to report offspring behavior could be subjected to two potential sources of bias – the first is the mental or emotional status of the parent and the second is gender-wise behavioral expectations from the child. The study by Otake et al. was based on one regional hospital treating pregnant women in the Sapporo area of Japan which could give rise to selection bias. They also reported a low participation rate (30%) which could have resulted in many depressed women being excluded from the study resulting in selection bias. Likewise, in the study by Bhang et al. on prenatal depression and infant development, development scores were only available for 50% of the infants, which could also give rise to a selection bias. The examiners for measuring infant development were blinded to other study data which minimized the chance of observer and reporting bias by Otake et al. The study by Nasreen et al. and Tran et al. was also conducted in a rural setting, and thus, the results may not be applicable for women residing in urban areas. Bhat et al. (2013), Park et al., Lin et al., and Zhu et al. did their studies on prenatal psychological distress and offspring temperament in a small sample which could impact the external validity of their study findings.
| Conclusion|| |
Common mental disorders during pregnancy which could be in the form of depression, anxiety, and self-perceived stress are strongly associated with offspring growth, development, and behavior in South and East Asia. Although the number of studies done in this area in the region is rather limited, especially in relation to studies on the objective measures of maternal stress, there is a growing interest and recognition of maternal mental health as an important public health concern.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Barker DJ, editor. Mothers, Babies and Health in Later Life. 2nd
ed. Edinburgh, United Kingdom: Churchill Livingstone; 1998.
Plant DT, Pawlby S, Sharp D, Zunszain PA, Pariante CM. Prenatal maternal depression is associated with offspring inflammation at 25 years: A prospective longitudinal cohort study. Transl Psychiatry 2016;6:e936.
Weinstock M. Does prenatal stress impair coping and regulation of hypothalamic-pituitary-adrenal axis? Neurosci Biobehav Rev 1997;21:1-0.
Schneider ML, Moore CF, Gajewski LL, Larson JA, Roberts AD, Converse AK, et al.
Sensory processing disorder in a primate model: Evidence from a longitudinal study of prenatal alcohol and prenatal stress effects. Child Dev 2008;79:100-13.
Agarwal R, Sankhyan A, Jain V. Normal growth and its disorders. Ghai Essential Pediatrics. 8th
ed. New Delhi: CBS Publishers; 2013.
Van den Bergh BR, Mulder EJ, Mennes M, Glover V. Antenatal maternal anxiety and stress and the neurobehavioural development of the fetus and child: Links and possible mechanisms. A review. Neurosci Biobehav Rev 2005;29:237-58.
Field T, Diego M, Hernandez-Reif M, Schanberg S, Kuhn C, Yando R, et al.
Pregnancy anxiety and comorbid depression and anger: Effects on the fetus and neonate. Depress Anxiety 2003;17:140-51.
Avishai-Eliner S, Brunson KL, Sandman CA, Baram TZ. Stressed-out, or in (utero)? Trends Neurosci 2002;25:518-24.
Rahman A, Iqbal Z, Harrington R. Life events, social support and depression in childbirth: Perspectives from a rural community in the developing world. Psychol Med 2003;33:1161-7.
Grote NK, Bridge JA, Gavin AR, Melville JL, Iyengar S, Katon WJ. A meta-analysis of depression during pregnancy and the risk of preterm birth, low birth weight, and intrauterine growth restriction. Arch Gen Psychiatry 2010;67:1012-24.
Rahman A, Bunn J, Lovel H, Creed F. Association between antenatal depression and low birthweight in a developing country. Acta Psychiatr Scand 2007;115:481-6.
Lin Y, Xu J, Huang J, Jia Y, Zhang J, Yan C. Effects of prenatal and postnatal maternal emotional stress on toddlers' cognitive and temperamental development. J Affect Disord 2017;207:9-17.
Satyanarayana VA, Lukose A, Srinivasan K. Maternal mental health in pregnancy and child behavior. Indian J Psychiatry 2011;53:351-61.
] [Full text]
Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JP, et al
. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: Explanation and elaboration. PLoS Med 2009;6:e1000100.
Dipietro JA. Maternal stress in pregnancy: Considerations for fetal development. J Adolesc Health 2012;51:S3-8.
Paul V, Bagga A. Essential Pediatrics. 8th
ed. New Delhi: CBS Publishers and distributors Pvt Ltd.; 2013.
Bhang SY, Ha E, Park H, Ha M, Hong YC, Kim BN, et al.
Maternal stress and depressive symptoms and infant development at six months: The mothers and children's environmental health (MOCEH) prospective study. J Korean Med Sci 2016;31:843-51.
Nasreen HE, Kabir ZN, Forsell Y, Edhborg M. Impact of maternal depressive symptoms and infant temperament on early infant growth and motor development: Results from a population based study in Bangladesh. J Affect Disord 2013;146:254-61.
Tran TD, Tran T, Simpson JA, Tran HT, Nguyen TT, Hanieh S, et al.
Infant motor development in rural Vietnam and intrauterine exposures to anaemia, iron deficiency and common mental disorders: A prospective community-based study. BMC Pregnancy Childbirth 2014;14:8.
Bhat A, Chowdayya R, Selvam S, Khan A, Kolts R, Srinivasan K. Maternal prenatal psychological distress and temperament in 1-4 month old infants – A study in a non-Western population. Infant Behav Dev 2015;39:35-41.
Park S, Kim BN, Kim JW, Shin MS, Yoo HJ, Lee J, et al.
Associations between maternal stress during pregnancy and offspring internalizing and externalizing problems in childhood. Int J Ment Health Syst 2014;8:44.
Zhu P, Sun MS, Hao JH, Chen YJ, Jiang XM, Tao RX, et al.
Does prenatal maternal stress impair cognitive development and alter temperament characteristics in toddlers with healthy birth outcomes? Dev Med Child Neurol 2014;56:283-9.
Su Q, Zhang H, Zhang Y, Zhang H, Ding D, Zeng J, et al.
Maternal stress in gestation: Birth outcomes and stress-related hormone response of the neonates. Pediatr Neonatol 2015;56:376-81.
Soe NN, Wen DJ, Poh JS, Li Y, Broekman BF, Chen H, et al.
Pre- and post-natal maternal depressive symptoms in relation with infant frontal function, connectivity, and behaviors. PLoS One 2016;11:e0152991.
Rahman A, Iqbal Z, Bunn J, Lovel H, Harrington R. Impact of maternal depression on infant nutritional status and illness: A cohort study. Arch Gen Psychiatry 2004;61:946-52.
Otake Y, Nakajima S, Uno A, Kato S, Sasaki S, Yoshioka E, et al.
Association between maternal antenatal depression and infant development: A hospital-based prospective cohort study. Environ Health Prev Med 2014;19:30-45.
Nath A, Murthy GVS, Babu GR, Di Renzo GC. Effect of prenatal exposure to maternal cortisol and psychological distress on infant development in Bengaluru, Southern India: A prospective cohort study. BMC Psychiatry 2017;17:255.
Fellmeth G, Plugge EH, Carrara V, Fazel M, Oo MM, Phichitphadungtham Y, et al.
Migrant perinatal depression study: A prospective cohort study of perinatal depression on the Thai-Myanmar border. BMJ Open 2018;8:e017129.
Sandman CA, Davis EP, Buss C, Glynn LM. Exposure to prenatal psychobiological stress exerts programming influences on the mother and her fetus. Neuroendocrinology 2012;95:7-21.
Huizink AC, Robles de Medina PG, Mulder EJ, Visser GH, Buitelaar JK. Stress during pregnancy is associated with developmental outcome in infancy. J Child Psychol Psychiatry 2003;44:810-8.
Davis EP, Sandman CA. The timing of prenatal exposure to maternal cortisol and psychosocial stress is associated with human infant cognitive development. Child Dev 2010;81:131-48.
Gitau R, Cameron A, Fisk NM, Glover V. Fetal exposure to maternal cortisol. Lancet 1998;352:707-8.
Buss C, Davis EP, Shahbaba B, Pruessner JC, Head K, Sandman CA. Maternal cortisol over the course of pregnancy and subsequent child amygdala and hippocampus volumes and affective problems. Proc Natl Acad Sci U S A 2012;109:E1312-9.
Huizink AC, de Medina PG, Mulder EJ, Visser GH, Buitelaar JK. Psychological measures of prenatal stress as predictors of infant temperament. J Am Acad Child Adolesc Psychiatry 2002;41:1078-85.
Grizenko N, Shayan YR, Polotskaia A, Ter-Stepanian M, Joober R. Relation of maternal stress during pregnancy to symptom severity and response to treatment in children with ADHD. J Psychiatry Neurosci 2008;33:10-6.
Gutteling BM, de Weerth C, Willemsen-Swinkels SH, Huizink AC, Mulder EJ, Visser GH. The effects of prenatal stress on temperament and problem behavior of 27-month-old toddlers. Eur Child Adolesc Psychiatry 2005;14:41-51.
Tsai AC, Scott JA, Hung KJ, Zhu JQ, Matthews LT, Psaros C, et al.
Reliability and validity of instruments for assessing perinatal depression in African settings: Systematic review and meta-analysis. PLoS One 2013;8:e82521.
Tran TD, Tran T, La B, Lee D, Rosenthal D, Fisher J. Screening for perinatal common mental disorders in women in the North of Vietnam: A comparison of three psychometric instruments. J Affect Disord 2011;133:281-93.
Okano T, Murata M, Masuji F, Tamaki R, Nomura J, Miyaoka H, et al
. Validation and reliability of Japanese version of EPDS. Arch Psychiatr Diagn Clin Eval 1996;7:525-33.
Aderibigbe YA, Gureje O. The validity of the 28-item general health questionnaire in a Nigerian antenatal clinic. Soc Psychiatry Psychiatr Epidemiol 1992;27:280-3.
Orr ST, James SA, Blackmore Prince C. Maternal prenatal depressive symptoms and spontaneous preterm births among African-American women in Baltimore, Maryland. Am J Epidemiol 2002;156:797-802.
Shang NX, Zou LP, Zhao JB, Zhang F, Li H. Association between prenatal stress and infantile spasms: A case-control study in China. Pediatr Neurol 2010;42:181-6.
Guddemi M, Sambrook A, Wells S, Randel B, Fite K, Selva G, Gagnon K. Arnold Gesell's developmental assessment revalidation substantiates child-oriented curriculum. SAGE Open 2014;4:1-18.
Bian XY, Tang L, Dong XY, Li HR, Peng YM, Chen R, et al.
Establishing the norm of cognitive adaptive test/clinical linguistic and auditory milestone scale in the children from 4 to 36 months of age in Shanghai, China. Zhonghua Er Ke Za Zhi 2005;43:782-6.
Matheny AP Jr., Wilson RS, Nuss SM. Toddler temperament: Stability across settings and over ages. Child Dev 1984;55:1200-11.
Achenbach TM, Edelbrock C. Manual for the Child Behavior Checklist and Revised Child behavior Profiles. Burlington: University of Vermont; 1983.
van Bakel HJ, Riksen-Walraven JM. Stress reactivity in 15-month-old infants: Links with infant temperament, cognitive competence, and attachment security. Dev Psychobiol 2004;44:157-67.
Najman JM, Williams GM, Nikles J, Spence S, Bor W, O'Callaghan M, et al.
Bias influencing maternal reports of child behaviour and emotional state. Soc Psychiatry Psychiatr Epidemiol 2001;36:186-94.
[Table 1], [Table 2], [Table 3]