Neonatal magnesium levels correlate with motor outcomes in premature infants: a long-term retrospective cohort study.

OBJECTIVE: Chronic neurological deficits are a significant complication of preterm birth. Magnesium supplementation has been suggested to have neuroprotective function in the developing brain. Our objective was to determine whether higher neonatal serum magnesium levels were associated with better long-term neurodevelopmental outcomes in very-low birth weight infants. STUDY DESIGN: A retrospective cohort of 75 preterm infants (<1500 g, gestational age <27 weeks) had follow-up for the outcomes of abnormal motor exam and for epilepsy. Average total serum magnesium level in the neonate during the period of prematurity was the main independent variable assessed, tested using a Wilcoxon rank-sum test. RESULTS: Higher average serum magnesium level was associated with a statistically significant decreased risk for abnormal motor exam (p = 0.037). A lower risk for epilepsy in the group with higher magnesium level did not reach statistical significance (p = 0.06). CONCLUSION: This study demonstrates a correlation between higher neonatal magnesium levels and decreased risk for long-term abnormal motor exam. Larger studies are needed to evaluate the hypothesis that higher neonatal magnesium levels can improve long-term neurodevelopmental outcomes.

Increasing supplemental thyroid hormone use among premature infants born at 23 to 32 weeks' gestation.

We assessed the pattern of levo-thyroxine (l-thyroxine) therapy in very premature newborns over a 10-year period. We analyzed the electronic database of a large private neonatal practice group (Pediatrix, Ft. Lauderdale, FL) for 23- to 32-week gestation neonates ( N = 96,813) managed during 1997 to 2006. L-thyroxine use was analyzed by birth year and by gestational age (GA). L-thyroxine use increased with decreasing GA (nadir 0.3% at 32 weeks, peak 8.4% at 24 weeks). L-thyroxine supplementation increased 2.6-fold over time among infants ≤26 weeks' GA (3.4% in 1997 to 1999 to 8.7% in 2004 to 2006), but did not change among infants born at ≥29 weeks' GA. The highest rate of l-thyroxine supplementation (12.8%) occurred among 24-week GA infants in 2006. Median age at start of l-thyroxine was 23 days (25 to 75%, 15 to 38 days). Only 2% of treated infants were started on day of life 1. Despite no clear evidence from randomized trials supporting thyroid supplementation, l-thyroxine treatment of very preterm infants has significantly increased over the past decade. As l-thyroxine treatment was not consistent with protocols from published randomized trials, new focused randomized controlled trials are needed.