Risk Factors for Plagiocephaly

By Phil Stevens, MEd, CPO, FAAOP
infant in cranial helmet

In a previous article, I discussed the commonly expressed concerns of parents of infants with deformational plagiocephaly regarding potential functional deficits associated with the condition ("Beyond Cosmetic Concerns: Functional Deficits Associated with Deformational Plagiocephaly," The O&P EDGE, April 2012). Another common concern is uncertainty about what might have caused or contributed to the development of the condition. Parents are often eager to know whether they inadvertently played a role or if they need to modify their parenting style to prevent it from occurring in subsequent children. While the presence of a flat spot may be quickly dismissed as the result of an infant spending too much time lying in the same position so a flattening of the skull occurs, this is an oversimplification that fails to accurately describe the factors that may have led to the development of plagiocephaly. While the 1994 "Back to Sleep" campaign is often blamed for this phenomenon, the majority of infants who sleep supine do not appear to develop plagiocephaly. This article provides a literaturebased analysis of the risk factors associated with plagiocephaly that will empower clinicians to provide parents with a more detailed answer to this common question.

It's Not as Straightforward as We Might Think

It is not uncommon to have parents of infants with plagiocephaly arrive at their first consultation nearly overcome by a sense of self-imposed guilt, feeling that this could have been avoided if they had somehow been better parents. In such cases, a degree of comfort can be provided using Bialocerkowski et al.'s systematic review.1 She and her team conducted a structured analysis of all of the literature published between 1985 and 2007 as it pertains to such things as the prevalence, risk factors, and natural history of deformational plagiocephaly.1 Within the 17 published studies included in their review, they identified 64 factors that have been investigated as potentially contributing to positional plagiocephaly. The various factors can be subdivided into sociodemographic and socioeconomic considerations, obstetric factors, infant characteristics, and aspects of infant care. While some of these are modifiable by the parents, others are not.

The list of factors that had some level of evidence supporting the possibility that they might contribute to the development of positional plagiocephaly include those listed in Table 1.

Table 1

Table 1: Factors that have been associated with the presence of deformational plagiocephaly. Bialocerkowski et al., 2008.1

Several of these considerations could be bound together as confounding variables. For example, a more educated mother might be more likely to receive antenatal education and as a result, choose supine positioning for her baby. Taken together, these collective observations underscore the reality that there are numerous considerations that may affect the development of plagiocephaly, and that several of these, such as gender, birth order, and prematurity, fall outside the realm of infant care variables.

infant in cranial helmet

Predictors of Severity

Clinicians who have accumulated some experience in the management of plagiocephaly recognize that there can be tremendous variability in the severity of the cranial asymmetries. A related question to the original, "What causes plagiocephaly?" is the inquiry, "What factors are associated with more severe deformational plagiocephaly?" A collaborative effort between Children's Boston Hospital, Massachusetts, and Hasbro Children's Hospital, Providence, Rhode Island, in which 434 infants with deformational plagiocephaly were examined, attempted to address this question.2

Among the maternal characteristics, such as age, ethnicity, prior medical history, or prior knowledge regarding plagiocephaly, none were correlated with the severity of the child's plagiocephaly.2 Among those variables associated with pregnancy, such as complications, approximate timing of fetal descent, length of labor, and fetal presentation, only one factor-the occurrence of a multiple-birth pregnancy-was associated with more severe plagiocephaly. Infants who were part of twin or triplet births had slightly more severe plagiocephaly than their singleton peers.2

Among infant characteristics, several factors were associated with more severe plagiocephaly. These included lower gestational age, male gender, positional preference for the head in infancy, prior diagnosis of torticollis, observable head tilt, and head rotational asymmetry.2 By contrast, several additional variables did not correlate with severity. These included birth weight, medical comorbidities, obvious developmental delay, age at which occipital flatness was first noted, or being firstborn.2 As might be expected, infants who were prone sleepers or had alternating sleep patterns had less severe plagiocephaly than those who were side or supine sleepers. However, perhaps surprisingly, these differences failed to reach statistical significance.2

Insights from the Northwest

Deformational plagiocephaly and its management with cranial remolding orthoses was first described in the late '70s and early '80s by Sterling K. Clarren, MD, at the Seattle Children's Medical Center, Washington.3 It seems only fitting that the center with the longest history of managing this condition contributes its observations on the perinatal characteristics apparently associated with plagiocephaly.4 In doing so, the researchers took a slightly different approach. After identifying all of the children with plagiocephaly managed by the medical center between 1987 and 2002, researchers identified five healthy controls for each one, matching the healthy infants to the affected infants according to the hospital and their birth year. Ultimately, researchers were able to evaluate 2,764 cases of plagiocephaly and 13,817 controls.4 The observations of this large-scale investigation underscore some of the trends discussed earlier in this article and are shown in Table 2.

Table 2

Table 2: Prevalence of perinatal considerations in infants with deformational plagiocephaly (cases) and matched controls (controls). Adapted from McKinney et al., 2009.4

At first glance, these statistics simply reinforce what has already been discussed. Infants with plagiocephaly are more likely than their unaffected peers to be male, slightly premature, have a lower birth weight, and be a product of a multiple-birth pregnancy. However, a few additional concepts are suggested by these observations.

First is the idea of intrauterine constraint. Several of the prominent risk factors for plagiocephaly also correlate to intrauterine constraint. These include being the firstborn child, male gender, the presence of congenital muscular torticollis, and being the product of a multiple-birth pregnancy. It seems reasonable to suggest that infants with less space within the uterus will be at an elevated risk to develop a flat spot as their heads are constrained against a rigid environment with limited room for movement. This is underscored by the observation that while the incidence of plagiocephaly is greater among twins and triplets than single births, it is the first-delivered infant who appears to be at the greatest risk. These babies are not only four and a half times as likely to develop plagiocephaly than their singleton peers, they are also more than two times as likely to develop plagiocephaly than their twin or triplet siblings.4

The second concept brought forth in this large-scale review is the idea of compromised perinatal mobility. Infants with plagiocephaly were more likely than their unaffected peers to be small for their gestational age and spent more time in the hospital during their first three months of life. Additionally, among infants with plagiocephaly, there were observations of increased incidences of perinatal injury, head injury, anomalies other than plagiocephaly, heart or respiratory anomalies, other central nervous system anomalies, Down syndrome, or other chromosomal anomalies.4 In other words, just as immobilization due to constraint appears to place an infant at an elevated risk for plagiocephaly, immobilization due to any of a number of birth injuries or congenital anomalies appears to have a similar effect.4

What Could We Have Done Differently?

By now it should be clear that many of the factors that appear to place infants at a greater risk for the presence and relative severity of plagiocephaly are outside of the parents' control. Factors such as the infant's gender, birth order, length of gestation, presence of multiple births, intrauterine constraint, or reduced perinatal mobility secondary to injury or congenital anomaly cannot be controlled or modified by parental effort. A final paper, recently published by a team of French researchers, brings our discussion back to the original idea of what parents can do differently to prevent the development of plagiocephaly.

In this paper, infants born in two neighboring cities were used to populate the control and intervention groups. Many of the comorbid conditions that might contribute to the development of plagiocephaly were excluded from the study design. Thus, infants born prematurely (<37 weeks), infants from triple pregnancies, those with congenital torticollis or other congenital malformations, and those with prolonged neonatal hospitalizations were not included in either study group.5

The infants born in the two cities underwent similar physical examinations within the first three days of life, and the parents were given standardized information on sudden infant death syndrome (SIDS) prevention and car safety. In addition, the parents from the town of Sète, the intervention group, received additional guidelines. In accordance with the recommendations of the American Academy of Pediatrics, parents were instructed to lay their infant to sleep in the supine position, alternating the infant's head position between the left and right occiput. Parents were further advised that when their baby was awake and being observed, he or she should spend time in the prone position. Further, the infant should spend minimal time in car seats when not a passenger in a vehicle. Similarly, parents were advised against other seating environments that maintain the supine position. Complementary advice was provided, proposing that parents and caretakers create an environment and care practices that promote "free and spontaneous movement right from birth."5

Infants from both cities had subsequent medical visits at 30, 60, and 120 days after birth. These appointments were with pediatricians independently selected by the parents and were not the same as those who conducted the immediate examinations of the infants and provided the neonatal recommendations. While these pediatricians had been trained to diagnose plagiocephaly, they were blinded to which group each infant was assigned.

At the time of the follow-up examinations, questionnaires were administered to assess parental compliance with positioning, including sleeping positions and environments. From these, researchers created mobility and immobility scores, reflecting the extent to which the additional instructions given to the parents in Sète had been implemented.

During the trial, 139 newborns were considered, 88 from the intervention group in Sète and 51 from the neighboring town of Bèziers, which constituted the control group.5 The infants in the intervention group largely experienced the targeted positions and environments. Compared to the infants in the control group, these infants slept more frequently in the supine position and spent significantly less time in the baby carrier or bouncer, whether awake or sleeping. During waking hours, they were placed on a play mat more often than their peers in the control group but spent less time overall on their bellies because they slept supine.

infant in cranial helmet

Of the 115 infants seen at the four-month follow up, 22 (19 percent) presented with deformational plagiocephaly. Among the infants in the control group, the incidence of plagiocephaly was 31 percent. By contrast, the incidence of plagiocephaly in the intervention group was only 13 percent, reflecting a 66 percent reduction in relative risk.5

This is the first study to demonstrate prospectively that alterations to parental education and the associated changes in parental choices regarding the positioning of their infants may reduce the prevalence of plagiocephaly. It is striking to observe that supine positioning alone cannot reasonably be seen as a primary cause of plagiocephaly because the infants in the intervention group were more likely to be positioned in supine, but ultimately less likely to develop plagiocephaly. Instead, it appears that the conscientious alterations of the baby's environments and positions, particularly when awake, coupled with a decreased dependence on infant carriers and bouncers, had the desired effect of reducing the rates of plagiocephaly in the intervention group.5

Summing It Up

While it is a simple matter to ascribe the increased incidence of deformational plagiocephaly as an unintended consequence of the "Back to Sleep" initiative, this answer fails to adequately address a number of additional considerations. The literature supports the position that there are multiple factors that may contribute to the development of deformational plagiocephaly. Some of these are choices that parents make as they decide where and how to position their baby during waking and sleeping hours. Others, such as the infant's gender, birth order, or the presence of multiple births, are well outside of parental control. Thus, while parents may reduce the likelihood of plagiocephaly through conscientious decisions about the positioning of their child, there are other considerations beyond their influence that may ultimately affect their infant's cranial symmetry.

Phil Stevens, MEd, CPO, FAAOP, is in clinical practice with Hanger Clinic, Salt Lake City, Utah. He can be reached at

References

  1. Bialocerkowski, A. E., S. L. Vladusic, and C. W. Ng. 2008. Prevalence, risk factors, and natural history of positional plagiocephaly: A systematic review. Developmental Medicine & Child Neurology 50 (8):577-86.
  2. Oh, A. K., E. A. Hoy, and G. F. Rogers. 2009. Predictors of Severity in Deformational Plagiocephaly. Journal of Craniofacial Surgery 20:685-9.
  3. Clarren, S. K. 1981. Plagiocephaly and torticollis: Etiology, natural history, and helmet treatment. Journal of Pediatrics 98:92-5.
  4. McKinny, C. M., M. L. Cunningham, V. L. Holt, et al. 2009. A case-control study of infant, maternal, and perinatal characteristics associated with deformational plagiocephaly. Paediatric and Perinatal Epidemiology 23 (4):332-45.
  5. Cavalier, A., M. C. Picot, C. Artiaga, et al. 2011. Prevention of deformational plagiocephaly in neonates. Early Human Development 87 (8):537-43.