Altered Fetal Head Growth in Preeclampsia: A Retrospective Cohort Proof-Of-Concept Study.

BACKGROUND: Preeclampsia is associated with fetal growth restriction and low birth weights. Neurotrophins, which mediate neuronal growth and development, are also increased in the placenta and cord blood in preeclampsia. Hence, the aim of this study was to determine whether fetal head growth is altered in preeclampsia, adjusting for growth restriction and other confounding variables. METHODS: This research included a retrospective cohort study, looking at fetal head circumference at birth, plus a case-control study examining fetal head circumference at mid-gestation. The head circumference at birth analysis consisted of 14,607 pregnancies (preeclampsia = 382, control = 14,225), delivered between July 2006 and June 2012 at Nepean Hospital, Australia. Head circumference at birth, in addition to other maternal and fetal variables, was sourced from the Nepean Obstetric Database. The head circumference at mid-gestation study consisted of 756 pregnancies (preeclampsia = 248, control = 508), delivered within the same data collection period at Nepean Hospital. Head circumference at mid-gestation was retrieved from an earlier ultrasound scan. Exclusion criteria included >1 fetus, illegal drug use, alcohol consumption, and chronic or gestational hypertension. Generalized linear models were used to analyze fetal head circumference in preeclampsia versus controls, adjusting for confounding variables. RESULTS: Head circumference increased at a greater rate in preeclampsia versus controls, adjusted for gestation, fetal gender, birth weight and length, smoking, maternal BMI, and growth restriction. At mid-gestation, there was no difference in head circumference between preeclampsia and controls. CONCLUSION: For the first time, this research has suggested increased fetal head growth in preeclampsia, adjusted for confounders. This finding may be explained by altered fetal exposure to neurotrophins in preeclampsia. The long-term neurodevelopmental consequences of preeclampsia remain unclear.

In utero Head Circumference is Associated with Childhood Allergy.

BACKGROUND: Altered fetal growth is known to be associated with allergic disease. Specifically, increased head circumference at birth has been linked to asthma and elevated IgE. However, few studies have examined a link between early fetal anthropometry and allergic disease. The aim of this study was to examine head circumference at mid-gestation in children diagnosed with allergy. METHODS: This was a retrospective cohort study, comprising pregnancies delivered between 10/2006 and 9/2010 at Nepean Hospital, Australia. Exclusion criteria were illegal drug use, alcohol consumption, gestation <35 weeks, and gestational hypertension. Pregnancy data were sourced from the Nepean Obstetric Database. Atopic diseases (asthma, atopic dermatitis, and IgE-mediated food allergy) were assessed by questionnaire at age 1-5 years. Infants from pregnancies with completed questionnaires, who also had a mid-gestation ultrasound scan, were included (N = 121). Multiple logistic regression techniques were used to model head circumference against the development of allergies. RESULTS: Smaller head circumference at mid-gestation was associated with increased odds of allergic disease in children aged 1-5 years. A 1 mm smaller head circumference was associated with a 7% increased chance of allergies being later diagnosed, adjusted for gestation (95% CI: 1-14%, p = 0.036). Head circumference at mid-gestation was also inversely correlated with the presence of multiple atopic disease. CONCLUSION: Smaller mid-gestational head circumference is associated with early childhood allergic disease, which suggests that fetal programing of allergic disease occurs before mid-gestation. This suggests that mediators such as brain-derived neurotrophic factor may be dysregulated early in utero in a milieu, which also predisposes to atopic disease.

Impaired fetal thymic growth precedes clinical preeclampsia: a case-control study.

In preeclampsia the maternal adaptive immune system undergoes specific changes, which are different from the physiological processes associated with healthy pregnancy. Whether preeclampsia also affects the fetal immune system is difficult to investigate, due to limited access to the fetus. We hypothesized that if preeclampsia affects the fetal adaptive immune system this might be associated with early changes in thymic growth. In this case-control study, 53 preeclamptic and 120 healthy control pregnancies were matched for maternal age, gestational age and smoking. Fetal thymus diameter was measured as the greatest width perpendicular to a line connecting sternum and spine based on ultrasound images taken at 17-21 weeks gestation. Independent of fetal and maternal anthropometric measures, thymuses were found to be smaller in preeclamptic pregnancies than healthy controls (16.2 mm versus 18.3 mm, respectively, mean difference=2.1 mm, 95% CI: 0.8-3.3, p<0.001), and the odds of developing preeclampsia was estimated to be 0.72 (95% CI: 0.60-0.86, p<0.001) lower for each 1 mm increase in thymus diameter. There was no correlation between the onset of preeclampsia and fetal thymus size. This is the first study to suggest that fetal thymus growth is reduced before the clinical onset of preeclampsia and precedes any described fetal anomalies or maternal immunological changes associated with preeclampsia. We propose that the fetal adaptive immune system is either passively affected by maternal processes preceding clinical preeclampsia or is actively involved in initiating preeclampsia in later pregnancy.