Prescriptive Reference Standards of Third-Trimester Cerebroplacental Ratio and Its Physiological Determinants

OBJECTIVE

To construct valid reference standards reflecting optimal cerebroplacental ratio and to explore its physiological determinants.

METHODS

A cohort of 391 low-risk pregnancies of singleton pregnancies of nonmalformed fetuses without maternal medical conditions and with normal perinatal outcomes was created. Doppler measurements of the middle cerebral artery and umbilical artery were performed at 24-42 weeks. Reference standards were produced, and the influence of physiological determinants was explored by nonparametric quantile regression. The derived standards were validated in a cohort of 200 low-risk pregnancies.

RESULTS

Maternal body mass index was significantly associated with the 5th centile of the cerebroplacental ratio. For each additional unit of body mass index, the 5th centile was on average 0.014 lower. The derived 5th, 10th, and 50th centiles selected in the validation cohort were 5, 9.5, and 51% of the measurements.

CONCLUSIONS

This study provides methodologically sound prescriptive standards and suggests that maternal body mass index is a determinant of a cutoff commonly used for decision-making.

[Relationship between lipid alterations during pregnancy and adverse pregnancy outcomes]

Lipids play an important role during pregnancy, and in this period major changes occur in lipoprotein metabolism. During the third trimester plasma cholesterol and triglyceride levels are substantially increased, returning to normal after delivery. Described associations between increased morbidity during pregnancy and excessive increases in plasma cholesterol and triglycerides. For this reason we have reviewed the relationship between lipid alterations, preeclampsia, gestational diabetes and preterm birth. The overall metabolic control can improve pregnancy outcomes, and the assessment of supraphysiological changes in lipid profile will classify pregnancy risk at a higher level, which would entail a stricter control.

Prevalence of dermographism in children

The prevalence of dermographism in our pediatric population was studied in 238 children of both sexes (128 boys and 110 girls) aged 2-14 years, randomly selected from a health care center. Skin reaction was evaluated after 5 min pressure (3,200 g/cm2) applied with a dermatographometer on a 5-cm length of dorsal skin. The reaction was considered positive when a wheal of more than 2 mm was observed. The prevalence of dermographism was found to be 24%, with a significant female predominance (33%) over males (16%). Forty-one percent of the children with dermographism reported exanthema in response to friction and pressure, which was compatible with symptomatic dermographism, compared with only 5% of those who yielded negative reactions. In order to assess the prevalence of dermographism in the atopic population, 100 patients in the 4-14 age range with respiratory disease (perennial allergic rhinitis and/or bronchial asthma) involving sensitization to aeroallergens (house dust mites and/or Alternaria) were studied. A positive response to the application of pressure (3,200 g/cm2) was observed in 47% of cases, this figure being significantly higher than in the general pediatric population.