Breech presentation is associated with lower bone mass and area: findings from the Southampton Women's Survey

We compared bone outcomes in children with breech and cephalic presentation at delivery. Neonatal whole-body bone mineral content (BMC) and area were lower in children with breech presentation. At 4years, no differences in whole-body or spine measures were found, but hip BMC and area were lower after breech presentation.IntroductionBreech presentation is associated with altered joint shape and hip dysplasias, but effects on bone mineral content (BMC), area (BA) and density (BMD) are unknown.MethodsIn the prospective Southampton Women's Survey mother-offspring cohort, whole-body bone outcomes were measured using dual-energy X-ray absorptiometry (DXA) in 1430 offspring, as neonates (mean age 6days, n=965, 39 with a breech presentation at birth) and/or at age 4.1years (n=999, 39 breech). Hip and spine bone outcomes were also measured at age 4years.ResultsNeonates with breech presentation had 4.2g lower whole-body BMC (95% CI -7.4 to -0.9g, P=0.012) and 5.9cm(2) lower BA (-10.8 to -1.0cm(2), P=0.019), but BMD was similar between groups (mean difference -0.007, -0.016 to 0.002g/cm(2), P=0.146) adjusting for sex, maternal smoking, gestational diabetes, mode of delivery, social class, parity, ethnicity, age at scan, birthweight, gestational age and crown-heel length. There were no associations between breech presentation and whole-body outcomes at age 4years, but, in similarly adjusted models, regional DXA (not available in infants) showed that breech presentation was associated with lower hip BMC (-0.51, -0.98 to -0.04g, P=0.034) and BA (-0.67, -1.28 to -0.07cm(2), P=0.03) but not with BMD (-0.009, -0.029 to 0.012g, P=0.408), or spine outcomes.ConclusionsThese results suggest that breech presentation is associated with lower neonatal whole-body BMC and BA, which may relate to altered prenatal loading in babies occupying a breech position; these differences did not persist into later childhood. Modest differences in 4-year hip BMC and BA require further investigation.