Prenatal exposure to heavy metal mixtures and anthropometric birth outcomes: a cross-sectional study.

BACKGROUND: Numerous studies have suggested significant associations between prenatal exposure to heavy metals and newborn anthropometric measures. However, little is known about the effect of various heavy metal mixtures at relatively low concentrations. Hence, this study aimed to investigate associations between prenatal exposures to a wide range of individual heavy metals and heavy metal mixtures with anthropometric measures of newborns. METHODS: We recruited 975 mother-term infant pairs from two major hospitals in Israel. Associations between eight heavy metals (arsenic, cadmium, chromium, mercury, nickel, lead, selenium, and thallium) detected in maternal urine samples on the day of delivery with weight, length, and head circumference at birth were estimated using linear and Bayesian kernel machine regression (BKMR) models. RESULTS: Most heavy metals examined in our study were observed in lower concentrations than in other studies, except for selenium. In the linear as well as the BKMR models, birth weight and length were negatively associated with levels of chromium. Birth weight was found to be negatively associated with thallium and positively associated with nickel. CONCLUSION: By using a large sample size and advanced statistical models, we could examine the association between prenatal exposure to metals in relatively low concentrations and anthropometric measures of newborns. Chromium was suggested to be the most influential metal in the mixture, and its associations with birth weight and length were found negative. Head circumference was neither associated with any of the metals, yet the levels of metals detected in our sample were relatively low. The suggested associations should be further investigated and could shed light on complex biochemical processes involved in intrauterine fetal development.

[ALTERATIONS IN SENSITIVE MEASURES OF CARDIAC FUNCTION IN HEALTHY NEONATES DURING PHOTOTHERAPY].

OBJECTIVES: Phototherapy has been reported to reduce coronary blood flow in neonates but without affecting gross measures of cardiac function. The aim of our current study was to evaluate earlier, more sensitive changes in cardiac function during phototherapy. METHODS: Nineteen neonates with jaundice treated with phototherapy had Doppler echocardiographic evaluation, before, during and after phototherapy and were compared to 25 matched controls. Sensitive measures for cardiac performance in this study included left ventricular dimension, ventricular Doppler parameters and regional function assessment. RESULTS: Phototherapy was associated with a significant increase in heart rate. In addition, atrioventricular valve closure to opening interval decreased significantly during phototherapy while ventricular ejection times tended to decrease. However, left and right ventricular filling parameters and outflow velocity parameters, longitudinal tissue-Doppler annular velocities and myocardial performance indices were not affected by phototherapy and were similar to those in controls. Coronary blood velocities and integrals decreased significantly during phototherapy. CONCLUSIONS: Our study found no differences in early and sensitive measures of cardiac performance including the diastolic and systolic function, despite modestly lower flow in coronary arteries among healthy neonates during phototherapy.

Effects of Phototherapy on Coronary Blood Flow in Healthy Neonates: A Pilot Study.

BACKGROUND: Phototherapy has been reported to alter blood flow to various tissues. We hypothesized that during phototherapy the coronary blood flow will decrease because of a 'steal effect' to the periphery. OBJECTIVES: To evaluate the effects of phototherapy on coronary blood flow in healthy, jaundiced, term neonates. METHODS: Flow velocity [peak diastolic velocity (Vd)] and flow measures [diastolic time velocity integral (TVId) and flow index (FI)] in the left main (LM) and left anterior descending (LAD) coronary arteries were prospectively studied with 2D/pulsed Doppler ultrasound before, during and after phototherapy in 19 healthy term, jaundiced neonates (study group) and in matched nonjaundiced controls (25 neonates). Significance was set at p < 0.05. RESULTS: The neonates' characteristics were comparable in both groups. Sequential studies in the study group showed no significant decrease in measures of velocity and flow during phototherapy; however, there was a significant increase in some of these measures (Vd and TVId in the LM coronary artery, and Vd in the LAD coronary artery) after phototherapy. Velocity (Vd) and flow measures (TVId and FI) in the LAD coronary artery, but not in the LM coronary artery, were significantly lower when comparing the study group during phototherapy with the controls. In a multivariate model, phototherapy was an independent variable affecting Vd and TVId in LAD coronary arteries. Measures of cardiac output did not change significantly throughout the study. CONCLUSIONS: While part of our findings may suggest a modestly lower flow in coronary arteries during phototherapy, we conclude that no clinically significant alteration in coronary arterial flow occurs during phototherapy in healthy term neonates.

Immediate versus delayed umbilical cord clamping in premature neonates born < 35 weeks: a prospective, randomized, controlled study.

The purpose of this study was to test whether delayed versus immediate cord clamping would result in higher blood pressure (BP) and hematocrit (Hct), and to assess its clinical effects on the neonatal course in premature neonates (< 35 weeks). This was a prospective, masked, randomized, controlled study. Prior to delivery, 35 neonates were randomly assigned to immediate cord clamping (ICC) at 5 to 10 seconds, and a comparable group of 30 neonates were randomly assigned to delayed cord clamping (DCC) at 30 to 45 seconds. Intention-to-treat analyses revealed that the DCC group tended to have higher initial diastolic BP and higher Hct (especially in vaginally delivered neonates). Infants weighing < 1500 g with DCC tended to have higher mean BP, and needed less mechanical ventilation and surfactant compared with ICC neonates. Infants with DCC did not experience more polycythemia (Hct > 60%), but had a trend toward higher bilirubin levels with no differences in the phototherapy needs. DCC seems to be safe and may be beneficial when compared with ICC in premature neonates. However, the differences between the two methods were modest and the clinical relevance needs to be assessed further by larger studies and additional meta-analysis of randomized trials.