From the Guidelines
If a mom has received magnesium during delivery, the newborn exam should be modified to closely monitor for potential effects of magnesium exposure, particularly in premature newborns who may have high levels of Mg in the first days of life 1.
Key Components of the Newborn Exam
- A thorough physical examination, paying close attention to the newborn's respiratory and neurological status
- Assessment of the newborn's muscle tone, reflexes, and respiratory effort, as magnesium can cause respiratory depression and muscle weakness
- Monitoring of the newborn's blood glucose levels, as magnesium can cause hypoglycemia
- Close monitoring of the newborn's oxygen saturation and heart rate, and initiation of oxygen therapy if necessary
Magnesium Toxicity
Newborns exposed to magnesium in utero should be monitored for at least 24-48 hours after birth for signs of magnesium toxicity, which can include drowsiness, lethargy, and poor feeding 1.
Magnesium Levels
A dose of 4-6 grams of magnesium sulfate administered to the mother during labor can result in newborn serum magnesium levels that are elevated for up to 24 hours after birth.
Clinical Considerations
It is essential to exercise caution and closely monitor the newborn for any signs of magnesium toxicity during this time, particularly in cases where the mother received high doses of magnesium sulfate or has renal failure 1.
From the Research
Newborn Examination Changes
If the mother received magnesium (Mg) sulfate during delivery, the newborn examination may change in the following ways:
- Lower 1-minute and 5-minute Apgar scores, as maternal serum magnesium concentrations increase before birth 2
- Increased risk of hypotonia, which is diagnosed if an infant exhibits less than normal tone/activity upon admission to the nursery 2, 3
- Higher incidence of respiratory depression or decreased tone 3
- Increased risk of admission to special care nursery 2
- Potential for brain lesions, including intraventricular hemorrhage (IVH) and lenticulostriate vasculopathy (LSV), particularly with high-dose MgSO4 exposure 4, 5
- Potential for periventricular leukomalacia, particularly with high neonatal serum magnesium concentrations 5
Factors Influencing Neonatal Outcomes
The following factors may influence neonatal outcomes:
- Maternal magnesium dose and serum concentrations 2, 5
- Duration of maternal magnesium therapy 5
- Neonatal serum magnesium concentrations, which should be within a therapeutic range for optimal neuroprotective effects 5
- Gestational age and maternal body mass index, which may affect neonatal serum magnesium levels 6
Clinical Implications
The studies suggest that:
- Pediatricians should attend deliveries of magnesium-exposed infants to monitor for potential complications 3
- Close monitoring of maternal serum magnesium concentrations and neonatal serum magnesium levels is necessary to minimize adverse outcomes 2, 5
- Further studies are needed to determine the optimal dose and duration of maternal magnesium therapy to minimize adverse neonatal outcomes 5