Skeletal growth lines seen on radiographs of newborn infants: prevalence and possible association with obstetric abnormalities.

OBJECTIVE

Skeletal transverse metaphyseal and vertebral lines, seen frequently on radiographs of infants and children, are usually believed to result from interrupted bone growth. Such lines have not been systematically studied in neonates. Accordingly, I determined the prevalence of growth lines on chest radiographs of newborn infants and assayed the gestational and obstetric abnormalities that occurred with these infants.

MATERIALS AND METHODS

Chest radiographs were obtained (over a 4-year period) in 3687 neonates within the first 48 hr after birth for clinical indications. A single observer prospectively examined the radiographs for the presence of skeletal lines. When skeletal lines were seen on chest radiographs, lines in the pelvis were also sought when this region was imaged during the first 48 hr after birth. The medical records of affected neonates were reviewed to determine the presence and nature of potential in utero injuries.

RESULTS

Skeletal lines were noted on chest radiographs of 200 neonates (5%) and appeared most commonly as "bone-within-bone" vertebral bodies and as transverse metaphyseal lines in the proximal humeri. Of affected neonates, 176 (88%) were born prematurely (< 38 weeks' gestation) and 59 (30%) had significant intrauterine growth retardation. Obstetric risk factors, which were varied and often multiple, were noted in 177 neonates (89%). The most common of these factors were pregnancy-induced hypertension (58 patients), multiple gestations (48 patients), drug abuse (30 patients), magnesium therapy (30 patients), prescribed maternal medications (27 patients), preterm labor before final labor (23 patients), and oligohydramnios (20 patients). In 23 neonates, no gestational complications were identified.

CONCLUSION

Skeletal lines in the population of neonates who require chest radiography are relatively common, and often but not invariably appear to occur in the setting of potentially significant prenatal injury. It is speculated that these lines represent a tool for identifying and exploring causes of intrauterine growth disturbance.