Chorioamnionitis and Earlier Gestational Age Are Associated with Neonatal Hypercalcemia After Maternal Magnesium Sulfate Therapy: A Case-Control Study

Abstract

BackgroundMagnesium sulfate (MgSO4) is a tocolytic agent used to treat gestational hypertension and to prevent preterm labor. Neonatal hypocalcemia is a well-known side effect of maternal MgSO4 use. Cases of neonatal hypercalcemia after maternal MgSO4 have been reported. Little is known about neonatal hypercalcemia following maternal MgSO4 therapy. We investigated the frequency and risk factors of neonatal hypercalcemia in this setting. MethodsThis case-control study investigated serum calcium in neonates born within 24 h after maternal MgSO4 administration. We reviewed the electronic medical records of Saitama City Hospital for pregnant women who were treated with MgSO4 between January 2016 and December 2021. There were 504 pregnant women that were treated with MgSO4. We enrolled 257 neonates. Hypercalcemia was defined as serum albumin-corrected calcium greater than 2.74 mmol/L (11 mg/dL). We collected the perinatal information from the mothers and neonates. ResultsTwenty-one neonates (8%) had hypercalcemia at birth (H group). Umbilical arterial ionized calcium, neonatal plasma ionized calcium, and total serum calcium were significantly higher in H group than in N group. Neonatal serum albumin, on the other hand, was lower in H group than in N group. Neonates in H group were born earlier (28.4 ± 3.1 vs. 32.4 ± 3.1 wk, p <0.001) and more likely to be born to mothers with pathological chorioamnionitis (91.0% vs. 12.7%, p <0.001) than neonates who were normocalcemic (N group). Serum alkaline phosphatase was lower in hypercalcemia group (661 ± 276 vs. 816 ± 265 U/L, p = 0.01). Multivariate analysis showed that earlier gestational age and chorioamnionitis were significant risk factors. ConclusionHypercalcemia after maternal MgSO4 was seen in 8% of neonates. Maternal chorioamnionitis and earlier gestational age were associated with this condition.