PubMed · 3484066
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Z Castañeda. [Growth and development].. https://pubmed.ncbi.nlm.nih.gov/3484066/
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STUDY DESIGN: The intrauterine axial rotational characteristics of the lumbar spine were analyzed and quantified sonographically. OBJECTIVES: To determine whether axial rotational movements of the lumbar spine occur prenatally, which may influence the morphogenesis of the zygapophysial joints. SUMMARY OF BACKGROUND DATA: Previously, the development of lumbar zygapophysial sagittal joint orientation was linked to the increase in torque of the torso as upright posture and locomotion are adopted. However, the potential influence of prenatal axial rotational movement of the lumbar spine on the development of the zygapophysial joints has not been examined. METHODS: For this study, 52 healthy fetuses, gestation age 9 to 36 weeks, were monitored sonographically for rotational movements of the lumbar spine. By multiplanar reconstruction of the sonography images, exemplary segmental rotational values were acquired. This method was validated by directly measuring the manually induced rotation of the formalin-fixated fetus in addition to multiplanar reconstruction. RESULTS: Axial rotations of the lumbar spine were seen in most of the examined fetuses ages 9 to 36 gestation weeks. Rotations are best assessable with multiplanar reconstruction in the second trimenon, when segmental rotation of the lower lumbar spine reaches a mean of 8 degrees (range, 4-10 degrees ). CONCLUSIONS: Fetal axial rotation of the lower lumbar spine reaches a degree that may functionally influence the morphologic development of the articular processes of the zygapophysial joints. In contrast to the prevalent hypothesis, lumbar spine development is already functionally influenced prenatally by axial rotation.
A model for foetal growth is developed and used to construct tools for diagnosis of intrauterine growth restriction. Foetal weight estimates are first transformed to normally distributed z-scores. The covariance structure over gestational ages is then estimated using a novel regression model. The diagnostic tools include individual growth curves with error bounds, probabilities to assess whether a foetus is small for its gestational age, and residual scores to determine whether current growth rates are unusual. The methods were developed sing data from 13593 ultrasound examinations involving 7888 foetal subjects. The model shows that median foetal growth velocity increases up to a gestational age of 35 weeks and then decreases during the final weeks of pregnancy. When growth is expressed as change in log weight, or equivalently as change proportional to current weight, the model reveals a constant deceleration as gestational age increases from 14 to 42 weeks.