Many NICUs implement Safe Sleep policies at around 32 weeks postmenstrual age, following a recommendation of the American Academy of Pediatrics (AAP)1. These policies often involve removing developmental positioning supports in an effort to model Safe Sleep for parents. Although implementing Back to Sleep as early as 32 weeks postmenstrual age is recommended, complete removal of developmental positioning supports may not be appropriate for all infants 2. It is important to consider the musculoskeletal and sensory organizational processes occurring in the infant between 32 weeks and term gestation.
Prematurity directly affects an infant’s ability to attain “positional stability.” Each infant’s medical and developmental needs should be considered before removing developmental positioning supports at a predetermined gestational age.
- Development of physiologic flexion posture, as the foundation of normal motor development, matures in the last weeks of pregnancy.
- Joint compression and resistance to active extension necessary for bone development is most prevalent in the last trimester.
- Calcium and phosphorus acquisition for bone ossification is maximized in the third trimester.
- The dynamic relationship between baby and boundary is an essential component of healthy physical and sensory development.
Developmentally speaking, removing positioning aids early in the 3rd trimester may deprive the baby of the increasing physiologic flexion they would have experienced in the womb, which is vital to bone and muscle development. A 32-week infant ideally requires an additional 6-8 weeks of pregnancy before neurologic and physical development are optimal. And, not every 32-week infant is the same physiologically or neurodevelopmentally.
A 32-week infant born at 24 weeks may have dramatically different physical and
sensory support needs than a 32-week baby born at 31 weeks.
Babies born at earlier gestations with more severe illnesses or congenital anomalies may require robust developmental support beyond full term, making traditional swaddles and wearable blankets developmentally ineffective.
Positioning with Purpose
In the third trimester, the “resistance training” provided by the muscular boundary of the uterus facilitates proper development of the bones, muscles, and joints. Preterm infants are born prior to the completion of the third trimester, placing them at risk for altered physical development.
- Active resistive movement is essential for skeletal development, along with maximized infant nutrition 4.
- The interaction between baby and the muscular-responsive uterus is essential in loading bones sufficiently to maximize bone accretion.
- During this formative period, an exponential increase in bone growth occurs, resulting in 80% of fetal bone being produced 3.
Commercially available wearable blankets generally allow for free movement, but may not provide recoil or promote a consistently flexed, midline posture — often leaving the lower extremities unsupported in extension. An ideal swaddle or wearable blanket provides dynamic resistance to extension of the extremities while promoting recoil to a flexed resting posture, mimicking the uterus.
Flexion and midline alignment in utero are important for physical development, self-regulation, digestion, and future motor milestones (rolling, crawling, and walking). Only when an infant can independently maintain midline flexion should they be considered as having attained positional stability.
The importance of continued developmental support into the third trimester is clear. Using a dynamic, developmentally-supportive swaddle aligns with premature infants’ musculoskeletal and sensory organizational needs and facilitates positional stability, while meeting AAP recommendations for Safe Sleep.
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