Can a C-Section affect babies’ brain development?
A number of media outlets have been reporting evidence that being born by C-Section can affect brain development. Many of the articles have specifically reported that this mode of delivery ‘slows a newborn’s ability to concentrate’ or even stronger can ‘impede a baby’s ability to concentrate’. But does the research study behind these stories provide concrete evidence for such claims?
What did the study do?
The study was conducted by Scott Adler and Audrey Wong-Kee-You based at the Department of Psychology and Centre for Vision Research, York University, Toronto, Canada. The study was published in the journal Attention, Perception and Psychophysics. The researchers reported on two experiments they conducted with 24 infants (experiment 1) and 12 infants (experiment 2). In both experiments, half the infants had been born by C-Section and half by vaginal delivery. The researchers were interested in examining different forms of attention. In experiment 1, the 3 month old infants performed a spatial-cueing task and in experiment 2 they performed a visual expectation task. The spatial-cueing task measures an infant’s stimulus driven reflexive attention and the visual expectation task measures voluntary attention. In a typical spatial-cueing task, the infants’ eye movements are recorded while they are presented with a peripheral cue which indicates the subsequent location of a target stimulus (such as an object the experimenter wants them to focus on). The cue grabs the infants attention to shift to the location prior to the target object being presented at that location. In the visual expectation task, the stimuli (such as an object) predictably appear on either the left and right sides of a monitor. This produces an increase in the infants’ eye movements because they anticipate the future appearance of the object.
What did the study find?
The researchers reported that the infants in the C-Section group had slowed performance on the spatial-cueing task in comparison to the vaginally delivered group. There were no differences between the groups on the visual expectation task. The authors inferred a relationship between mode of delivery and effects on some forms of attention.
How did the media handle reporting of the findings?
The media by and large have reported the difference between the groups on the spatial-cueing task as indicative of the mode of delivery having affected brain development. The study did not randomly assign infants to a C-Section versus vaginal delivery though. Obviously this would be ethically impossible. In that case therefore we need to be very careful to consider other confounding factors that may have influenced the findings. The researchers did account for potential differences in maternal age across the two groups. There are a whole host of factors however that they did not control for that could very plausibly have influenced the results. As the authors themselves note in their discussion of their findings in the paper, there was no control for whether the C-Section was planned or caused by an emergency. Neither do the authors report on the reasons why a C-Section was needed whether planned or not. There may of course be maternal reasons for a C-Section but it is also likely that infant factors may have influenced the decision for a C-Section. Was an emergency C-Section required because the baby was in distress for example? We cannot glean that information from this study. There are therefore numerous reasons, other than the mode of delivery, that could explain why the C-Section group performed more slowly on the spatial-cueing task.
The effects of C-Section on neurodevelopment are often the focus of research and it is quite common to see reports of how detrimental they could be. For example, we previously reported on another study, in this case a meta-analysis (a study of other studies), that over zealously reported a link between autism and C-Sections.
The bottom line
Media reports that suggest this study provides evidence that C-Section delivery slows or impedes brain development is simply over-egging these results. Highly plausible confounding factors that could otherwise explain the results cannot be ruled out. Even more concerning though is the commenting within some of the reporting about how ‘growing numbers of women are choosing to have caesareans because they are very anxious about giving birth naturally’. Interpreting the findings as causal to impaired brain development, and at the same time making statements that suggest that most C-Sections are now ‘chosen’ because of anxiety within the same report, is merely trying to sensationalise serious birth decisions.
Adler, S. A. & Wong-Kee-You, A. M. B. (2015). Differential attentional responding in caesarean versus vaginally delivered infants. Attention, Perception, & Psychophysics. DOI:10.3758/s13414-015-0969-3