The Moro Reflex: A Neurodevelopmental Occupational Therapy Perspective on Integration, Birth Factors, and Sensory Outcomes
Written by: Earl Mamaril MS OTR/L @sensorytherapywithearl
The Moro reflex is one of the earliest and most significant primitive reflexes present at birth. According to Rousseau et al. (2017), this reflex emerges as a brainstem-mediated survival response and typically becomes inhibited between 3–6 months of age as cortical pathways mature. The reflex follows a characteristic two-phase sequence: a sudden abduction and extension of the upper extremities, followed by an embracing, flexion-based return toward midline. This pattern is most often triggered by unexpected vestibular shifts or abrupt sensory input, reflecting the infant’s early attempt to signal distress, regain equilibrium, and recruit caregiver proximity.
From a neurodevelopmental occupational therapy perspective, the timely integration of the Moro reflex is essential. As higher cortical regions strengthen, they gradually assume regulatory control over this brainstem pattern, enabling the transition from automatic reactivity to voluntary, adaptive responding. Researchers have noted that persistence of the Moro reflex beyond 6 months may indicate delayed central nervous system maturation, sensory modulation difficulties, or disruptions in early multisensory processing (Rousseau et al., 2017).
Vestibular integrity also plays a crucial role. Bloomfield et al. (2008) demonstrated that the Moro reflex depends on intact vestibular structures; infants with semicircular canal abnormalities may exhibit absent or atypical Moro responses. This finding highlights that reflex interpretation must consider broader sensory system development rather than viewing primitive reflexes in isolation.
Moro Reflex Integration and Sensory Processing Outcomes:
A growing body of evidence suggests that delayed Moro reflex integration may influence sensory modulation, emotional regulation, and motor development. Because the Moro reflex is tightly coupled with early autonomic activation, prolonged retention may maintain the child in a heightened state of sympathetic arousal. Researchers studying sensory processing patterns report that sensory processing disorders are disproportionately common in infants born via cesarean section or prematurely—affecting as many as 80–84% in some samples—compared to term infants born vaginally. Although the mechanisms differ across studies, evidence consistently points to altered early stress responses, reduced hormonal signaling, and atypical sensory system activation in these groups.
According to multisensory integration research, structures such as the superior colliculus require rich, early sensory experiences to support the maturation of cortical–midbrain communication pathways. When the Moro reflex remains active, these pathways may not organize efficiently, contributing to oversensitivity, avoidance, or difficulty with transitions later in childhood.
Influence of Cesarean Birth on Reflex Integration and Neurological Adaptation
Several studies indicate that mode of delivery, especially elective cesarean section without labor, may influence the trajectory of Moro reflex integration. According to Otamiri and colleagues (1991, 1992), infants born via elective cesarean section exhibit significantly lower catecholamine levels at birth—hormones essential for neurological readiness, respiratory transition, stress regulation, and sensory responsiveness. This hormonal attenuation corresponds with delayed neurological adaptation and weaker Moro reflex expression during the first 48–72 hours of life.
Cesarean delivery also bypasses the compressive, proprioceptive, and vestibular stimuli provided during vaginal birth. These mechanical forces are believed to contribute to pulmonary expansion, autonomic priming, and early sensory calibration, all of which support primitive reflex integration. Evidence from Zaigham et al. (2020) and Zago et al. (2023) further indicates that infants born via prelabor cesarean section may demonstrate lower developmental scores at 3–12 months of age, particularly in gross and fine motor domains. These findings suggest that altered birth physiology can have cascading effects on neuromotor organization and reflex maturation.
Longitudinal data indicate that children born by cesarean section continue to show elevated odds of developmental delay at age 3 (Sznajder et al., 2020). Researchers attribute these outcomes to a combination of hormonal, microbial, mechanical, and epigenetic factors—many of which influence early sensory system development and HPA-axis functioning.
Maternal and Perinatal Factors in Reflex Development
Maternal metabolic or endocrine conditions may compound the risks associated with cesarean delivery. Sznajder et al. (2020) found that elevated maternal BMI, thyroid disorders, and diabetes were independently associated with increased odds of neurodevelopmental delays in infants born via cesarean section. Additionally, intrapartum medical interventions—such as prophylactic antibiotics or synthetic oxytocin—are known to modify neonatal microbiome acquisition and influence early immune-neural signaling. These factors may interact with primitive reflex expression, sensory responsiveness, and subsequent neurodevelopmental outcomes.
Conclusion
Taken together, the research suggests that the Moro reflex is not merely an early motor pattern but a sophisticated neurobiological marker reflecting brainstem maturation, sensory system integrity, hormonal signaling, and early environmental experiences. From an occupational therapy framework, understanding the interplay between reflex integration, birth conditions, and sensory development is essential for designing interventions that support autonomic regulation, motor competence, and functional participation throughout childhood.
Supplementary Learning: Video Demonstrations and Expert Conversations
To support families, educators, and clinicians in recognizing real-world Moro reflex patterns, the following video resources offer visual and conversational insight into how this reflex presents and why its integration is essential for neurodevelopment.
1.Preschool Moro Reflex Response: What It Looks Like in Real Time
2.My Interview With Dr. Carla Hannaford: Understanding the Moro Reflex Through a Neurobiological Lens
3.Simple Moro Reflex Integration Exercise (neurodevelopmental OT-Guided Home Practice)
REFERENCES
Bloomfield, F. H., Dai, S., Perry, D., & Aftimos, S. (2008). Isolated absence of the Moro reflex in a baby with CHARGE syndrome could reflect vestibular abnormalities. Journal of Child Neurology, 23(5), 561–563. https://doi.org/10.1177/0883073807309779
Otamiri, G., Berg, G., Finnström, O., & Leijon, I. (1992). Neurological adaptation of infants delivered by emergency or elective cesarean section. Acta Paediatrica, 81(10), 797–801. https://doi.org/10.1111/j.1651-2227.1992.tb12106.x
Otamiri, G., Berg, G., Ledin, T., Leijon, I., & Lagercrantz, H. (1991). Delayed neurological adaptation in infants delivered by elective cesarean section and the relation to catecholamine levels. Early Human Development, 26(1), 51–60. https://doi.org/10.1016/0378-3782(91)90043-3
Rousseau, P. V., Matton, F., Lecuyer, R., & Lahaye, W. (2017). The Moro reaction: More than a reflex, a ritualized behavior of nonverbal communication. Infant Behavior & Development, 46, 169–177. https://doi.org/10.1016/j.infbeh.2017.01.004
Sznajder, K. K., Teti, D., Hackman, N. M., Massare, B., & Kjerulff, K. H. (2020). Cesarean section and child development at 3 years: A prospective cohort study of first births in Pennsylvania. Maternal and Child Health Journal, 24, 1543–1553. https://doi.org/10.1007/s10995-020-03013-2
Zaigham, M., Hellström-Westas, L., Domellöf, M., & Andersson, O. (2020). Prelabour Caesarean section and neurodevelopmental outcome at 4 and 12 months of age: An observational study. BMC Pregnancy and Childbirth, 20, Article 564. https://doi.org/10.1186/s12884-020-03253-8
Zago, A. C., Trettim, J. P., Rubin, B. B., et al. (2023). Early motor development: Risk factors for delay in a population study in southern Brazil. Revista de Saúde Pública, 57, Article 59. https://doi.org/10.11606/s1518-8787.2023057004991
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