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Keywords:

  • bonding disorder;
  • Edinburgh Postnatal Depression Scale;
  • maternal mood;
  • Mother-to-Infant Bonding Scale;
  • post-partum period

Abstract

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Aim

Postnatal depression has demonstrated long-term consequences on child cognitive and emotional development; however, the link between maternal and child pathology has not been clearly identified. We conducted a prospective study using self-rating questionnaires to clarify the association between bonding disorder and maternal mood during pregnancy and after childbirth.

Methods

A total of 389 women participated in this study and completed questionnaires. Participants were asked to complete the Edinburgh Postnatal Depression Scale (EPDS) and the Mother-to-Infant Bonding Scale four times during pregnancy and the postpartum period.

Results

We found statistically significant weak to moderate correlations (r = 0.14–0.39) between the EPDS and Mother-to-Infant Bonding Scale scores at each testing period. Women who experienced low mood tended to have stronger bonding disorder. Furthermore, the effectiveness of attachment between the mother and child was closely related to the mood of the mother as measured by the EPDS.

Conclusion

We observed different patterns of bonding and maternal mood. Distinct subtypes regarding maternal mood and formation of mother-to-infant attachment suggests that analysis of bonding disorder should be performed considering the course of maternal depressive symptoms.

Bonding is the process of developing a relationship and attachment between mother and newborn child. In general, the maternal instinct begins when the mother meets her baby for the first time. A bonding disorder occurs when there is difficulty forming an attachment between mother and child. Bonding disorder has been acknowledged as an important problem in perinatal psychiatry.[1, 2] However, it has not been recognized as a nosological category either in the ICD-10 or the DSM-IV. Several factors can lead to the onset of bonding disorder, for example: death of a twin baby, stillbirth, painful delivery, or undesired pregnancy.[3] It has also been reported that infants with diseases, handicaps, or delays in social interaction due to premature birth are risk factors for bonding disorder.[4] In addition, the mother's severe anxiety, a compulsive temperament, or distress due to difficulty with feeding, calming the infant, and getting the child to sleep can interfere with the development of attachment[2] and severe parenting problems, such as child neglect or abuse, may impact effective bonding.

Depression and low mood are common symptoms that may be present during gestation, the puerperal period, or the menopausal period. Therefore, biological factors, such as hormonal imbalance, and psychosocial factors, such as changing roles of home and society, might influence the onset of depression or influence mood. ‘Postpartum depression’ is used to describe a continuum of depressive symptoms and diagnoses that occurs several weeks after childbirth. Postpartum depression occurs in approximately 10–15% of women.[2, 5-10] A recent clinical study showed that estimated rates of depression during pregnancy vary from 7 to 15% in developed countries to 19 to 25% in developing countries.[11] Moreover, more than half of women with postpartum depression suffer from depression before or during pregnancy.[12] Studies focused on a Japanese population reported that about 16% of women experience depression or low mood during pregnancy and postpartum.[13, 14]

The gestation and puerperal periods are very important for developing mother–child bonding and the mother's depression during these critical periods may prevent effective bonding.[3] Furthermore, the importance of bonding for the cognitive and behavioral development of infants is well known.[15] When postpartum depression is prolonged, the adverse influences on mother–child bonding become more prominent. Specifically, the risk of abuse and neglect increase if the mother's depression is not treated. Moreover, long-term effects continue to impact the mother–child dyad. One study suggested that children of mothers who have had postpartum depression are more likely to have cognitive and emotional problems throughout development.[16]

Several questionnaires have been used to assess bonding in severely ill clinical inpatients,[17] mothers whose babies were in intensive care,[18] and maternal representations of attachment during pregnancy.[19, 20] Moreover, many groups have studied the process of bonding between mother and child. Specifically, Brockington et al.[1] reported on the use of the Postpartum Bonding Questionnaire, a self-rating instrument to assess the mother–infant relationship, as a screening instrument to detect bonding problems in obstetric and primary care services. Taylor et al.[21] developed the Mother-to-Infant Bonding Scale (MIB) to screen the general British population for postpartum difficulties in relation to maternal emotions toward the baby.

There are two major hypotheses regarding bonding disorder. One hypothesis suggests that postpartum depression is the primary disorder and that the bonding disorder is caused by improper treatment of the mother's depression. The other theory suggests that the mother-to-infant relationship is the primary concern, and that bonding disorder can occur even if maternal depression is not present.[2] Righetti-Veltema and colleagues reported that mother–infant relationship was correlated to the Edinburgh Postnatal Depression Scale (EPDS), but an intermediate or pathological score on mother–infant relationship tests was observed in 8.8–21.8% of mothers without depressive symptoms.[16] In other words, there is a controversy about whether the mother's mood disorder, such as depression, secondarily causes trouble with relations with the child, or if bonding development and difficulty in caring for the infant influence the mother's mental health.

Kumar analyzed features of 44 women who showed serious maternal affective disorders. Results showed that mothers who did not have any mental disorders after childbirth did not have inadequate maternal emotions. However, he reported that he could not completely clarify the contexts because the onset of the mental disorder and bonding disorder were so close, and the progression of the mental disorder did not correspond completely with the clinical course of the bonding disorder.[3] Condon studied bonding dynamics between mothers and unborn children during pregnancy. According to him, there is a pathological dyad between a mother and her fetus that starts before the baby is born, and he reported some cases of fetal abuse.[22, 23] A similar study was conducted in Japan,[20] and results suggested an association between depressive tendency of a mother and attachment to the unborn child. However, there is no report that examines changes in the relation of depressive symptoms and bonding disorder from the pregnancy period to after childbirth using the same evaluation scale. Moreover, a large number of studies have examined and reported the rates of depression among women in the postpartum period,[2, 12] but in most of them, samples were collected after the onset of depression; therefore, the possibility of recall bias cannot be excluded.

From a preventive point of view, the potential links between maternal pre/postnatal mood and mother–infant bonding need to be investigated in greater detail. Therefore, we conducted a prospective study using self-rating questionnaires to investigate the correlation between bonding disorder and maternal depression during pregnancy and after childbirth. The objectives of this study were to analyze the course of infant–mother attachment, and to assess the association between bonding disorder and maternal depressive state during pregnancy and the postpartum period.

Methods

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Participants

A total of 551 participants were recruited randomly at two obstetrical hospitals in Nagoya, Japan between August 2004 and October 2009. After a demographic interview, we asked subjects to complete the MIB and the EPDS. The aforementioned instruments were designed to assess attachment between mother and child as well as the presence of depressive state related to pregnancy and childbirth. A total of 389 women completed all questionnaires necessary for the analysis; one subject was excluded as an extreme outlier.

The current study is part of a larger project focused on perinatal mood disorders[14, 24] and detailed information about sampling procedures is available elsewhere.[14] Although there is partial overlap between samples used in the aforementioned studies and the current study, the samples are not exactly the same, as we did not get 100% completeness in terms of questionnaires. All subjects provided written informed consent after the study was described to them. The Nagoya University Graduate School of Medicine and Nagoya University Hospital ethics review committee approved this study.

Procedures

The first tool was the MIB, which is designed to screen the general population for postnatal difficulties in relation to maternal emotions toward a new baby.[21, 25] The MIB consists of eight statements describing an emotional response, such as ‘loving’ or ‘disappointed’, which are rated on a 4-point Likert scale from ‘very much’ (0) to ‘not at all’ (3); total scores can range from 0 to 24. Low scores denote good bonding. Besides being quick and easy to use, this tool has shown reported good internal reliability and a positive correlation with the EPDS.[26] In the current study, participants were required to complete the MIB at four time points: during an early pregnancy period (before 25 weeks), during late pregnancy (around 36 weeks), at 5 days after delivery, and at 1 month postpartum. Although the MIB was originally a screening scale for bonding after childbirth, we examined the development of the attachment to the fetus during pregnancy using the same evaluation items, based on the statement: ‘When I have spoken about or thought about the developing baby, I got positive emotional feelings.’

The second tool we used was the EPDS.[27] The EPDS has been validated in the Japanese population and has been used for screening for depressive symptomatology in the Japanese clinical setting.[28] This scale is a set of questions designed to assess if a new mother has depressive mood. The total score is calculated based on the answers to 10 items. Although the EPDS does not provide a clinical diagnosis of depression, the higher the score, the more likely it is that the person completing the questionnaire may be depressed. The cut-off point of 8/9 used in the current study is based on the data from a previous study focused on validity and reliability of the EPDS in the Japanese population.[28] Participants were asked to complete the EPDS according to the same schedule as the MIB.

The women who participated in this study were classified into four groups based on the presence or absence of low mood. Based on an EPDS cut-off point of 8/9, the four groups were: (i) non-depressive group (scored under the cut-off point on the EPDS); (ii) temporary gestational depressive group (scored over the cut-off point on the EPDS only during pregnancy); (iii) continuous depressive group (scored over the cut-off point on the EPDS during pregnancy and after delivery); and (iv) postpartum depressive group (scored over the cut-off point on the EPDS after delivery). We sought to further investigate the interaction effect in the developing pattern of the MIB score between the four EPDS groups. In the study by Taylor et al.,[21] the sample was stratified into high or low MIB groups based on a threshold score (4 points). Following this cut-off point, we divided the sample in the present study into a high MIB group (subjects who scored 4 or more) and a low MIB group (subjects who scored less than 4).

Pearson correlation coefficients (r) were calculated to examine associations between the EPDS and MIB scores. To evaluate differences in MIB scores between the four EPDS groups, we used a repeated measure anova. Longitudinal trends of MIB scores were examined by classifying the subjects into four groups according to the pattern of bonding based on the threshold reported in a previous study:[21] (i) no bonding disorder (scored less than 4 during the pregnancy period and at 1 month postpartum); (ii) gestational bonding disorder group (scored 4 or more only during pregnancy); (iii) postpartum bonding disorder (scored 4 or more only at 1 month postpartum); and (iv) continuous bonding disorder (scored 4 or more during both pregnancy and postpartum). We examined differences in the proportion of each group's mood states by Fisher's exact test. Data were analyzed using spss 17.0J (spss, Tokyo, Japan). Significance was determined at the 0.01 level for all tests.

Results

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Table 1 shows the mean age and number of women in each of the four groups based on EPDS scores, after exclusion of one subject who was an extreme outlier in terms of EPDS and MIB scores. The mean age of subjects was 31.7 years (range, 20–44 years; SD, 4.3 years). Of the 388 women, 282 (72.7%) belonged to the non-depressive group; 39 (10.0%) were in the temporary gestational depressive group; 27 (7.0%) were in the continuous depressive group; and 40 (10.3%) were in the postpartum depressive group. Although uniparous mothers were more often found to be in the postpartum depressive group, there was no statistical difference regarding experiences of delivery among the four groups (Table 1). There were no differences regarding income and academic backgrounds.

Table 1. Women who completed the EPDS at all four periods were divided into groups based on results of the EPDS scores
PregnancyPostpartumGroupsn (%)Age (years ± SD)Parity
Early pregnancyLate pregnancy1 monthUniparousBiparousMultiparous
  1. Based on course of maternal depressive symptoms. No depressive state (under EPDS cut-off point). §Depressive state present. (above EPDS cut-off point).

  2. EPDS, Edinburgh Postnatal Depression Scale.

Non-depressive282 (72.7%)31.8 ± 4.11768620
+§Temporary gestational depressive39 (10.0%)31.9 ± 5.42694
+
++
+Postpartum depressive40 (10.3%)32.0 ± 4.13442
++Continuous depressive27 (7.0%)30.5 ± 4.41692
++
+++

The hypothesis that maternal mood was related to bonding was tested with a Pearson correlation of EPDS measures. There were weak to moderate correlations (r = 0.24–0.39; P < 0.01) between the EPDS and MIB scores during early pregnancy, during late pregnancy, and at 1 month postpartum (Fig. 1a,b,d); the weakest correlation (r = 0.142) was observed at 5 days after delivery (Fig. 1c). The prospective design of our study gave us the opportunity to examine the difference in the developmental trend of the MIB score among the four EPDS groups.

figure

Figure 1. Correlation between Mother-to-Infant Bonding Scale (MIB) and Edinburgh Postnatal Depression Scale (EPDS) scores. The data-points are shown as numbers, while each number represents count of subjects at each data-point. The data-density (count of subjects per data-point) is shown using the blue color gradient. [Correction added on 30 July 2014, after first online publication: Figure was redrawn and replaced to improve its clarity.]

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The MIB score of the continuous depressive group was the highest in all groups during pregnancy, decreased after delivery, and then went up at 1 month postpartum (Fig. 2). The score of the postpartum depressive group was lower than the continuous depressive group's during pregnancy, but increased after childbirth (Fig. 2). The mean, SD, median, and quartile MIB score for each period of the current study are shown in Table 2. Four groups based on the EPDS scores and four groups based on the MIB scores were summarized in the cross table, and we calculated the proportion of the four groups based on MIB score by each group based on the EPDS score (Table 3). A majority of the subjects did not score over the MIB scale threshold. However, we detected tendencies that the gestational bonding disorder group made up a large proportion of the temporary gestational depressive group, and the continuous bonding disorder group represented a large proportion of the continuous depressive group. Analysis revealed a statistical association between the proportion of women in the four MIB groups and the proportion of women in the four groups based on EPDS (Fisher's exact test P < 0.0001).

figure

Figure 2. Mean Mother-to-Infant Bonding Scale (MIB) score at four time-points in women classified in four Edinburgh Postnatal Depression Scale groups. Groups based on course of maternal depressive symptoms. image, Non-depressive group; image, Temporary gestational group; image, Postpartum depressive group; image, Continuous depressive group.

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Table 2. Mean and median of MIB scores
 Early pregnancyLate pregnancyAt 5th dayAt 1st month
  1. MIB, Mother-to-Infant Bonding Scale.

Mean (SD)2.09 (2.49)2.15 (2.43)0.89 (1.55)1.28 (1.82)
Median (25–75%)1 (0–3)1 (0–3)0 (0–1)0 (0–2)
Minimum0000
Maximum1316810
Table 3. Number (%) of women in four groups based on MIB by four groups based on EPDS
Groups based on EPDS scoreFour groups based on MIB Score n (%)
No bonding disorderGestational bonding disorderPostpartum bonding disorderContinuous bonding disorder
  1. Based on course of maternal depressive symptoms.

  2. EPDS, Edinburgh Postnatal Depression Scale; MIB, Mother-to-Infant Bonding Scale.

Non-depressive216 (55.7%)44 (11.3%)11 (2.8%)11 (2.8%)
Temporary gestational depressive26 (6.7%)10 (2.6%)2 (0.5%)1 (0.3%)
Postpartum depressive22 (5.7%)6 (1.5%)8 (2.1%)4 (1.0%)
Continuous depressive12 (3.1%)6 (1.5%)3 (0.8%)6 (1.5%)

Discussion

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

In the current study, we observed a weak to moderate correlation between the EPDS scores and the MIB score during early pregnancy, during late pregnancy, at the 5th day after delivery, and at 1 month postpartum. There was a tendency that higher EPDS scores were associated with more severe bonding disorders. An interaction effect was observed in the developing pattern of the MIB between the four groups based on the EPDS scores. The MIB scores of the continuous depressive group were the highest in comparison with the other groups during pregnancy, decreased once after delivery, and then went up at 1 month postpartum. The scores of the postpartum depressive group were lower than the continuous depressive group's during pregnancy, but increased after childbirth. When we calculated the proportion of the four groups based on the MIB scores and of each group based on the EPDS, there were various patterns in the development of bonding. In other words, some of the mothers who had low MIB scores were not in a depressive state at 1 month postpartum, but others were. In Robson and Kumar's study,[25] although some mothers were indifferent to their newborn babies 7 days after delivery, most mothers developed bonding within 1 week. Some studies indicated that women with low bonding in late pregnancy were at risk of poorer bonding with their infant postpartum.[19, 29] However, until this study, no report has examined the longitudinal trend of bonding from early pregnancy to postpartum using the same questionnaire.

In the current study we observed that the MIB scores after childbirth were lower than during pregnancy. Some mothers had not developed an appropriate maternal emotional response during pregnancy, but bonding gradually formed. The MIB score at 5 days after delivery was the lowest of the four time-points, and the score 1 month postpartum rose slightly. This differs from findings of Taylor et al.,[21] who showed that average bonding scores 12 weeks after childbirth were 67% lower than those recorded 3 days after childbirth, indicating that mother–infant bonding scores had improved considerably between these two occasions. In Japan, most women are still in the hospital 5 days after delivery. We believe that the MIB score at 5 days in our study was slightly lower than the score reported in the previous UK study[21] because mothers did not realize the difficulty of child care and the associated lack of sleep that accompanies caring for an infant. The four groups, as classified by the EPDS, were different in terms of the development pattern of MIB. On the one hand, the MIB score in the postpartum depressive group was low during pregnancy, which was a similar pattern to the non-depressive group. On the other hand, the MIB score in the continuous depressive group was already high during pregnancy, which suggested an association between depressive state and bonding disorder. The continuous depressive group had high EPDS scores in the early pregnancy period; they might appear to have experienced low mood before pregnancy, but that was not confirmed in the current study.

It has been shown that depressive symptomatology during pregnancy can affect the development of mother-to-infant bonding.[30] In reference to the controversy of whether depression or bonding disorder is the primary disorder, for mothers in the continuous depressive group, depression was regarded as a causal factor in previous studies, as the mothers had depressive mood during pregnancy. On the other hand, for mothers in the postpartum depressive group, the bonding disorder might be one of the factors influencing low mood.[31] In a recent study,[29] it was reported that poor attachment in late pregnancy predicted postpartum depression, but that study did not completely clarify the context of its findings. Our colleagues have observed different time sequences regarding the depressive state.[14] These differences were not investigated in previous studies focused on the association between bonding disorder and maternal depression.[3, 15, 25, 32] Furthermore, we found that there were some women with a high MIB score even though they did not experience low mood. This result is consistent with previous studies,[3, 33] indicating that the progression of the depressive state does not correspond completely with the clinical course of bonding disorder, and suggesting that, in some cases, bonding disorder is not a direct consequence of the depressive state. Therefore, in order to investigate factors related to the development of bonding disorder that are not related to depression, research focused on the mother's social interactions and attachment style is needed.

The following cautionary details should be considered when interpreting the results of the current study. We did not use a psychiatric interview to establish the diagnosis of depression. We used self-administered questionnaires and we did not analyze comparative performance of the Japanese version of EPDS and other depression rating scales, such as the Beck Depression Inventory or the Japanese version of the Quick Inventory of Depressive Symptomatology. It is of note, however, that EPDS was validated in a Japanese sample for screening for depression.[28] In addition to the high false-negative rate in the self-rating scale, due to fear of negative evaluation,[17] it is important to consider that cognitive deviations due to depressive influences may influence the results of this type of questionnaire.[34] Although the MIB is short and easy to use, the cut-off point in the present study was not verified in the clinical setting. Furthermore, the validity and reliability of the MIB for assessing attachment during pregnancy were not verified in the current study; this questionnaire was originally developed to assess mother-to-infant bonding after childbirth and its use during pregnancy has not been verified. Another limitation is that bonding disorder of women who were identified as belonging to the postpartum depressive group may have been influenced by various factors related to delivery (such as hormonal regulation, obstetric complications, and maternal blues), which were not considered in the current study. Furthermore, as we investigated bonding only from pregnancy to 1 month postpartum, additional research regarding bonding disorder after 1 month and its influence on cognitive development is needed. In addition, as significant changes have been found in physiological and psychological functions in different trimesters of pregnancy,[35, 36] a time-specific threshold might be appropriate.[37] However, as these data have not been validated in the Japanese population, we used the same cut-off (8/9) in the present study.

Finding potential risk factors during pregnancy is extremely important not only for the mother but also for the newborn child. To clarify the risks related to bonding disorder, future studies should include a larger sample size, as well as additional information regarding social support from a woman's spouse and mother, the mother's temperament, and the mother's parenting experience.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Funding for this study was provided by research grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan and the Ministry of Health, Labor and Welfare of Japan, the intramural Research Grant (21B-2) for Neurological and Psychiatric Disorders of National Center for Neurology and Psychiatry and the specific research fund 2012 for the Great East Japan Earthquake Revival by the New Technology Development Foundation. We declare that we have no conflicts of interest. Authors' Contributions: S.G., S.M., A.K., T.M. and N.O. designed the study. H.O., N.I. and K.F. participated in collecting clinical information and samples. H.O., T.K., S.G., S.M., A.K., T.M., B.A. and N.O. analyzed, interpreted and discussed the results. H.O., T.K., B.A. and N.O. wrote the draft. H.O., T.K. and B.A. wrote the final manuscript.

References

  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References