School of Healthcare Science, Manchester Metropolitan University, Manchester, UK.
MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK.
Osteoporos Int. 2018 Oct;29(10):2275-2281. doi: 10.1007/s00198-018-4626-2. Epub 2018 Jul 12.
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 4 years, no differences in whole-body or spine measures were found, but hip BMC and area were lower after breech presentation.
Breech presentation is associated with altered joint shape and hip dysplasias, but effects on bone mineral content (BMC), area (BA) and density (BMD) are unknown.
In 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 6 days, n = 965, 39 with a breech presentation at birth) and/or at age 4.1 years (n = 999, 39 breech). Hip and spine bone outcomes were also measured at age 4 years.
Neonates with breech presentation had 4.2 g lower whole-body BMC (95% CI -7.4 to - 0.9 g, P = 0.012) and 5.9 cm lower BA (- 10.8 to - 1.0 cm, P = 0.019), but BMD was similar between groups (mean difference - 0.007, - 0.016 to 0.002 g/cm, 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 4 years, 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 - 0.04 g, P = 0.034) and BA (- 0.67, - 1.28 to - 0.07 cm, P = 0.03) but not with BMD (- 0.009, - 0.029 to 0.012 g, P = 0.408), or spine outcomes.
These 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.
我们比较了分娩时臀位和头位婴儿的骨骼结局。臀位新生儿的全身骨矿物质含量（BMC）和面积均低于头位新生儿。4 岁时，全身或脊柱测量值无差异，但臀位后髋部 BMC 和面积较低。
臀位与关节形状改变和髋关节发育不良有关，但对骨矿物质含量（BMC）、面积（BA）和密度（BMD）的影响尚不清楚。
在前瞻性南安普顿女性调查母婴队列中，1430 名后代在新生儿期（平均年龄 6 天，n=965，其中 39 例为出生时臀位）和/或 4.1 岁时（n=999，其中 39 例为臀位）使用双能 X 射线吸收法（DXA）测量全身骨量。4 岁时还测量了髋部和脊柱的骨量。
臀位新生儿全身 BMC 低 4.2g（95%CI-7.4 至-0.9g，P=0.012），BA 低 5.9cm（-10.8 至-1.0cm，P=0.019），但两组间 BMD 相似（平均差异-0.007，-0.016 至 0.002g/cm，P=0.146），调整性别、母亲吸烟、妊娠期糖尿病、分娩方式、社会阶层、产次、种族、扫描年龄、出生体重、胎龄和头臀长。臀位与 4 岁时的全身结果无相关性，但在同样调整的模型中，区域性 DXA（婴儿不可用）显示臀位与较低的髋部 BMC（-0.51，-0.98 至-0.04g，P=0.034）和 BA（-0.67，-1.28 至-0.07cm，P=0.03）相关，但与 BMD（-0.009，-0.029 至 0.012g，P=0.408）或脊柱结果无关。
这些结果表明，臀位与新生儿全身 BMC 和 BA 较低有关，这可能与胎儿在臀位时的产前负荷改变有关；这些差异在儿童后期并未持续存在。4 岁时髋部 BMC 和 BA 的适度差异需要进一步研究。
