Researchers aim to investigate the causes and potential treatments for perinatal intrusions — intense and vivid thoughts that impact most people during and after pregnancy.
Intrusive and distressing thoughts affect virtually all mothers, opens in a new window during pregnancy and beyond, but little is known about their causes and ways to treat them, due to a lack of evidence in what a UNSW scientist calls a “completely neglected” field of research.
Now researchers from UNSW Sydney and the George Institute will redress this knowledge gap by embarking on a five year study into ‘perinatal intrusions’, which they outline in a focus article published today in the journal Science Advances, opens in a new window.
“Intrusions are thoughts of infant-related harm that women can have during the pregnancy, or more commonly, in the first year after childbirth, or postpartum,” says Scientia Associate Professor Susanne Schweizer, who is leading the research in UNSW Science.
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“So the type of thoughts that most women will have are thoughts of accidental harm – like imagining the baby falling off a changing table, or a pram rolling away – and these are quite vivid images that seem to come out of nowhere.”
But perhaps more distressing, not to mention isolating, are thoughts of causing intentional harm to the infants.
“Half of all women who give birth will additionally have thoughts of intentionally harming their baby. Again, these thoughts come out of nowhere and it’s one of the worst things you can think of as a human being.”
A/Prof. Schweizer stresses that these thoughts are very common and are not linked to behaviour that goes beyond these thoughts and is acted upon. She compares it to the fleeting thought about stepping off the ledge of a high cliff when in close proximity to a lethal drop that many people experience.
“It makes sense from an evolutionary perspective that women are extremely sensitised to threats in the caregiving environment, because their infant is entirely dependent on them being alert to those threats,” she says.
But knowing that it may have evolutionary roots and may be designed to keep mothers and infants safe doesn’t stop the thoughts from causing distress. A/Prof. Schweizer says some women will be particularly vulnerable to these perinatal intrusions developing into an anxiety disorder that could negatively affect both mother and infant.
“There is barely a handful of people worldwide looking into this at the moment, mainly because the perinatal period is a completely neglected area of research.
“So we’re trying to redress that and understand why women are vulnerable to these thoughts. We know that more intense, more distressing, more frequent, intrusive thoughts are associated with worse perinatal outcomes, not just in the mental health for the mother, but also in terms of the baby’s emotional wellbeing.”
Hormones and the perinatal period
The research that the UNSW team and collaborators in India and Canada are embarking on will focus on the social, biological and cognitive factors that contribute to the heightened vulnerability to mental health problems women experience in the perinatal period. One part of the study will look at the role hormones play on a mother’s cognition and mood during the perinatal period.
“We already know from menstrual cycle research that some women are very susceptible to the hormonal changes that occur during the cycle,” A/Prof. Schweizer says.
“For some, it’s so extreme that it can lead to actual symptoms of depression, complete hopelessness and an inability to be motivated to do anything, and a lack of pleasure.”
The researchers are planning to map hormone fluctuations across the perinatal period to see if any patterns emerge.
“Identifying who is susceptible to hormone sensitivity, and why, is crucial to implementing early intervention, and even prevention, strategies to bolster women’s mental health during the peripartum,” the researchers say in the article.
Looking ahead: intrusive thoughts for mothers
The research team is working with women with lived experience of perinatal mental health problems to design the research materials for a first study from this project that is launching in the next few weeks. This study will track women across the perinatal period and measure intrusive thoughts and how they are associated with mothers’ mental health through a range of possible factors such as women’s thinking styles, hormone sensitivity and social connectedness.
A/Prof. Schweizer says this work is much needed, and she hopes that the knowledge this research advances will ensure expectant parents and their healthcare providers are better prepared and informed about the range of experiences women may have in this unique period of life.
“Today most healthcare providers and parents are aware of the possibility of postpartum depression, the ‘baby blues’,” she says.
“Expectant parents are currently not routinely informed that they will likely have intrusive thoughts and that some will also experience perinatal anxiety as well as a range of other mental health conditions. Armed with this knowledge women at-risk can be identified and supported earlier, so that more – hopefully, one day, all – mothers and babies can thrive.”
Source: University of New South Wales
Published on March 19, 2025