When thinking about maternal mental health and how difficulties with it may influence a developing baby, it is only natural to imagine the postpartum period — that is, the year following a woman’s birth to her baby — given that this is when mothers can for the first time interact with their babies face-to-face. And in fact, the majority of research on maternal mental health to date has focused on the postpartum. Equally important, and less studied, though, is how a woman’s mental health during (and even before) pregnancy can frame how she will enter motherhood and how her baby will adjust accordingly. And, furthermore, how their relationship together may develop.
An outcome of maternal depression in pregnancy that hasn’t been widely studied is the mother-infant relationship, which is my specific area of focus. I am a postdoctoral researcher at the Institute of Psychiatry, Psychology and Neuroscience in the perinatal psychiatry section of the Stress, Psychiatry, and Immunology Lab, the group who publishes InspireTheMind. The topic of my PhD was whether depression experienced prior to birth — in pregnancy or just in lifetime before pregnancy — may affect the development of one of the most fundamental relationships.
Antenatal depression is defined as a depressive episode experienced during a woman’s pregnancy and has become increasingly common, especially during the COVID-19 pandemic. The core symptoms are typically low mood, lack of interest, changes in appetite, difficulties with sleep, and ongoing feelings of guilt and worthlessness. It is now thought to affect up to 1 in 5 pregnancies and can either occur spontaneously during pregnancy or as a continuation of symptoms that began prior to conception.
While the root of its onset is not entirely understood, researchers believe that a combination of social and biological risk factors may underpin the emergence of symptoms. Notable risk factors for becoming unwell include: a history of childhood abuse, previous depressive episodes, socioeconomic difficulties, young age, lower education qualifications, lack of social support, changes to circulating stress hormones, and increased inflammation throughout the body. This is not to say that all pregnant women who meet the criteria for any of the above-listed experiences will become depressed; rather, that women who are depressed are much more likely to possess one or more of these risk factors.
What impact does antenatal depression have?
Many studies have investigated what (if any) effect antenatal depression can have on mothers’ outcomes and have found that expectant mothers who are depressed may have trouble with self-care and care of the unborn baby, are more likely to remain depressed in the postpartum, and are at heightened risk of having suicidal thoughts. Upsettingly, the leading cause of maternal death in the postpartum is in fact suicide, highlighting the importance and urgency of identification and treatment of depression.
While care of expectant mothers is vital, clinicians and researchers also agree that care for the unborn baby is just as crucial, as antenatal depression is found to affect development throughout different stages of life: our research group has found that in the neonatal period, offspring are more likely to show behavioural difficulties in the first week of life, including decreased social-interactive behaviour, seen through reduced gaze and vocalizations; we have also found that in infancy, offspring are at risk for disruptions in their biological systems, including alterations in their stress hormones and inflammatory markers; as infants develop into children, they are more likely to experience mental health difficulties, including depression and anxiety; and finally, they are at risk for these psychopathologies to continue all the way through to adulthood. Put simply, there seems to exist a transmission of vulnerability from mother to child, highlighting the importance of breaking this chain at the outset.
As I mentioned above, while there is a lot of research to date on the impact of antenatal depression on offspring development, few other studies have investigated the association between depression in pregnancy and the mother-infant relationship. As such, this was the focus of my PhD work. In addition to looking at antenatal depression, I also chose to examine maternal historical depression — women who had a history of a depressive episode but were well in pregnancy — to understand whether different timings of depressive episodes can differently affect mother-infant behavioural patterns.
Depression and the mother-infant relationship
Before I discuss my findings, it’s important to understand the significance of the mother-infant relationship. It is thought that mothers begin bonding with their babies as early as the first trimester of pregnancy, suggesting that this relationship begins in utero, not in the postpartum. In fact, studies have shown that a mother’s feelings towards her developing foetus and how she engages with it in her second trimester are highly predictive of what her parenting behaviours will be like later on. Additionally, researchers have long found connections between the quality of the mother-infant relationship (usually observed through attachment, which assesses an infant’s sense of security as a result of sensitive mothering behaviour) and the infant’s psychological wellbeing later in life. And so, given that a mother’s feeling about her foetus are predictive of their postpartum relationship, and that the infant’s attachment status is predictive of subsequent mental health, there’s an inherent importance in monitoring women during pregnancy to identify any risk factors that may affect the developing relationship.
This is where my research fits in: I wanted to understand whether maternal depression in pregnancy or prior to pregnancy impacted the quality of the mother-infant relationship across the postpartum period, in order to explore whether mother-infant interventions need to be extended to the pregnancy period. Moreover, I also examined whether other risk factors in addition to depression — such as maternal socioeconomic difficulties, like lack of social support or low income, maternal history of childhood abuse, maternal postpartum depression, and infant difficult behaviour — played into the potential association between antenatal or history of depression and a decreased quality of interaction. The reason I chose to also look at these factors is because research shows that they are both associated with antenatal depression and the mother-infant relationship, which means it’s possible they’d be involved in the pathway from depression to relationship difficulties.
To evaluate the quality of the relationship, I watched videos of mothers and their babies interacting at 2 months and 12 months postpartum, and assessed how well their interaction with each other went; that is, how well mothers could comfortably engage their babies, how babies responded to their mothers’ behaviour, and how in-sync the dyad were as a whole, almost as if the interaction is a dance. What I found was that dyads in both the antenatal depression group and the history of depression group didn’t have as smooth a back-and-forth and couldn’t connect as well as dyads in a healthy comparison group at both 2 and 12 months. While I expected to find this in the antenatal depression group, I was surprised to learn that the history of depression group was just as impacted, given that these mothers were well in pregnancy, the timepoint when women begin to bond with their babies.
I also found that maternal socioeconomic difficulties and less-social neonatal behaviour contributed to this association, overall suggesting that mothers with depression are also likelier to experience socioeconomic hardship, their infants are more at risk to display behavioural difficulties early on, and altogether the two members of the dyad struggle to connect optimally across the postpartum period. These results above all point to the complexities with which women with depression can present, and that their vulnerabilities are often multi-layered and may transmit to their infants. And, as I have previously discussed, that not all mothers get the appropriate care they are entitled to because of barriers in our healthcare systems. Reassuringly, though, I did observe that the quality of the relationship improved significantly between 2 months and 12 months, suggesting that with time, early struggles in the relationship can be ameliorated.
What does this mean clinically?
With these results in mind, it’s important to consider the clinical implications of depression (in pregnancy and in lifetime) on the mother-infant relationship. While relationship support is routinely available for mothers with postpartum mental health problems and their infants, I believe this support should be extended to both mothers who are depressed in pregnancy and mothers who have a history of depression, even if they are well in pregnancy. Pregnancy is a period during which women are in routine contact with healthcare professionals and would therefore provide an optimal opportunity for support in bonding with the foetus and future infant by educating expectant mothers on sensitive caregiving, ways to engage and respond, and developmental milestones to look out for. Moreover, I believe that interventions proven to help the mother-infant relationship, such as video feedback and structured mother-baby activities, should be made more widely available.
And that’s where my current research comes in: I am now working on SHAPER — recently written about in another blog — the world’s largest clinical trial to investigate the impact of guided mother-baby singing sessions on maternal depression and the mother-infant relationship. Ideally this kind of support can help women to feel more confident and prepared for their journey into motherhood by providing building blocks for an optimal, healthy relationship with their babies. And hopefully mothers will enjoy doing so in the process by singing along with other women and their babies!