Primitive reflexes are involuntary, stereotypic movement patterns originating in the central nervous system. They emerge during intrauterine life and are fully present at birth in healthy term infants. These automatic responses help the newborn survive extrauterine transition by supporting feeding, protection, and early motor coordination. As the cerebral cortex matures over the first few months of life, these primitive movements are gradually inhibited, making way for voluntary, purposeful motor skills. Evaluating these reflexes offers the midwife a vital window into the integrity and maturation of the neonatal nervous system without needing complex equipment.
The Moro reflex, often called the startle reflex, is provoked by any sudden sensory input that simulates a brief loss of support. Midwives most commonly elicit this by performing a controlled, gentle head drop of a few centimeters while supporting the infant's upper body, or by striking the surface next to the baby. When the infant perceives this abrupt change in equilibrium, the reflex immediately fires. It is important to perform this test with care so the baby is neither frightened unnecessarily nor injured during handling.
A normal Moro response consists of two distinct phases. First, the infant abducts and extends both arms symmetrically while opening the fingers and often taking a quick gasp. Second, the arms adduct back across the chest in an embracing motion, usually accompanied by crying.
| Response Type | Clinical Presentation |
|---|---|
| Normal | Symmetrical abduction, extension, then adduction with open hands |
| Abnormal (Asymmetrical) | One arm moves while the other stays limp, often pointing to nerve injury |
| Abnormal (Absent) | No movement observed at all, suggesting severe central nervous system depression |
An asymmetric response often indicates a clavicle fracture or a brachial plexus injury like Erb's palsy sustained during a difficult birth.
The Moro reflex provides invaluable insight into the health of both the central and peripheral nervous systems. Because it requires intact pathways from the brainstem down through the spinal nerves and out to the limbs, a missing or hyperactive response serves as an early warning sign. Infants with severe birth asphyxia, intracranial hemorrhage, or major cerebral malformations often display absent or severely depressed reflexes. Conversely, an exaggerated, jittery response can point toward neonatal abstinence syndrome, severe hypocalcemia, or acute intracranial irritation. Midwives rely on these subtle physical cues to decide when a newborn needs urgent pediatric review.
Accurate record-keeping is essential after assessing any neonatal reflex. The midwife must document the exact quality, symmetry, and completeness of the Moro response in the baby's healthcare chart. If the response is asymmetrical, sluggish, or entirely missing, prompt escalation is required. Do not delay informing the attending physician or paediatric team when abnormal neurological signs appear, as early detection of birth trauma or hypoxic ischemic encephalopathy improves long-term outcomes. Clear communication ensures the newborn receives timely diagnostic investigations like X-rays for fractures or specialized neurological evaluations.