Effect of severe maternal hypoxia on fetal rat size: brain protection by magnesium sulfate

M. Hallak, J. W. Hotm

Research output: Contribution to journalArticlepeer-review


OBJECTIVE: To determine whether severe maternal hypoxia during the third trimester of pregnancy may affect fetal rat body and hrain weight and size, and whether magnesium sulfate (MgSO4) may reverse this effect. STUDY DESIGN: Four groups of pregnant rats (n = 21) were studied at 17 gestational days. Group #1: Saline injected and room air (RA, n = 6); Group #2: MgSO4 injected and room air (n = 5); Group #3: Saline injected and hypoxia chamber (n = 5); Group #4; MgSO4 injected and hypoxia chamber (n = 5). Subcutaneous maternal MgSO4 injection protocol included a loading dose of 270 mg/kg followed by 27 mg/kg every 20 minutes for 4 hours. Saline rats were injected with the same volume and schedule. Hypoxia chamber protocol included a gas mixture of 9% ox\gen, 3% CO2, and nitrogen for 2 hour period. Tail venous blood was collected for gases and magnesium levels at the beginning and conclusion of the exposure period. After 72 hours of recover)', at 20 days' gestation, cesarean sections were performed, fetuses delivered and brains obtained intact. Fetal body and brain weight and si/e were measured. Statistical analysis of the data was performed using analysis of variance and post hoc test. RESULTS: Exposure to the gas mixture resulted in decreased maternal pO2 from 82.8 ±20.0 mmHg to 49.2 ±14.4 mmHg (p < 0.005), and pH from 7.37 ±0.05 to 7.20 ±0,04 (p < 0.0001). No significant change in maternal pCOy stattis have been noted. Exposure to the MgSO4 injection protocol resulted in increased blood magnesium level from 1.52 ±0.2 to 3.77 ±0.7 (p < 0.0001). Fetal: Weight-gm Saline & RA MgSO4 & RA Saline & Hypoxia MgSO4, & Hypoxia Body Weight 3.5 ±0.1 3.4 ±0.0 3.6 ±0.1 3.5 ±0.1 Brain Weight 0.19 ±0.0 0.19 ±0.20 ±0.0 0.21 ±0.0 Body Si/e 37.3 ±2.7 37.4 ±1.9 36.5 ±2.2* 36.3 ±1.5* Brain Size 8.22 ±0.1 8.18 ±0.1 7.06 ±0.0* 8.08 ±0.0 *p < 0.05 CONCLUSION: Severe maternal hypoxia resulted in decreased fetal body and brain size. Peripheral maternal MgSO4 administration prevented the effect of hypoxia on fetal brain size. No effect of MgSO4 on body size was noted.

Original languageEnglish
Pages (from-to)S167
JournalActa Diabetologica Latina
Issue number1 PART II
StatePublished - 1 Dec 1997
Externally publishedYes

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism
  • Endocrinology


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