Several authors have suggested that the final
five weeks of gestation are a critical period for the development
of the hip. In order to test the hypothesis that gestational age
at birth may influence the development of the hip joint, we analysed
the sonographic findings in 1992 hips (in 996 term newborns) with
no risk factor for developmental dysplasia of the hip. The 996 infants
were born at a mean gestational age of 39 weeks (37 to 41). The mean bony roof angle (α), cartilage roof angle (β) and the
distribution of the type of hip were compared between the 37th,
38th, 39th, 40th and 41st birth week groups. There was a significant
difference in the distribution of type of hip between the different
birth week groups (p <
0.001), but no significant difference
between the α angles of all groups (p = 0.32). There was no correlation
between birth week and roof angle (p = 0.407 and p = 0.291, respectively)
and no significant correlation between birth weight and roof angle
(p = 0.735 and p = 0.132, respectively). The maturity of the infant hip, as assessed sonographically,
does not appear to be affected by gestational age, and the fetal
development of the acetabular roof appears to plateau from 37 weeks. Cite this article:
