Effect of magnesium sulfate exposure on term neonates.

OBJECTIVE: To compare neonatal intensive care unit and special care unit (NICU) admission rates between term neonates exposed to antenatal magnesium sulfate (MS) and those unexposed. STUDY DESIGN: We performed a retrospective cohort study of all singleton neonates ≥37 weeks born to women with pre-eclampsia from August 2006 to July 2008. Cases were defined by antenatal exposure to MS and controls by absence of MS exposure. The primary outcome was NICU admission. Data were analyzed via univariable and multivariable regression analyses. RESULT: In all, 28 (14.7%) out of 190 MS-exposed neonates ≥37 weeks were admitted to the NICU, compared with 4 (5.4%) of 74 non-exposed neonates (P=0.04). This association persisted after controlling for potential confounding variables including severe pre-eclampsia and cesarean delivery (AOR 3.69, 1.13 to 11.99). NICU admission was associated in a dose-dependent relationship with total hours and mean dose of MS exposure. Number needed to harm with MS was 11 per NICU admission. Among neonates admitted to the NICU, MS-exposed were more likely to require fluid and nutritional support than unexposed neonates (60.7 vs 0%, P=0.04), and trended toward more frequent requirement for respiratory support and greater length of stay. CONCLUSION: In term neonates, MS exposure may be associated independently with NICU admission in a dose-dependent relationship. Requirements for fluid and nutritional support are common in this group, likely due to feeding difficulties in exposed neonates. Assessment of acute care needs among all neonates exposed to MS for maternal eclampsia prophylaxis should be considered.

Donation of blood by the pregnant patient for autologous transfusion.

A study was conducted to determine the safety and utility of autologous blood donation in third trimester pregnancy. Thirty-seven obstetric patients, 32 with an obstetric risk factor, donated an average of 485 ml of blood. Twenty-one of the 37 patients were expected to undergo cesarean section. Nonstress testing was performed before and after phlebotomy. Continuous fetal heart rate monitoring was maintained throughout the donation, which lasted an average of 9 minutes. All nonstress test results were normal before and after the phlebotomy except in one case. All fetal heart rates remained stable during phlebotomy and premature labor was not precipitated. All fetal outcomes were normal. One patient delivered on the day of phlebotomy, 6 hours after the procedure. Only one of the autologous units was used, in a patient who had a pelvic infection and moderate anemia. The incidence of primary cesarean section was 35%. Phlebotomy of the mother appears to be safe for the fetus at term. Further investigation is needed to determine the safety of removal of more than 1 unit of blood and blood donation at earlier gestational ages.

Fetal heart rate response to vibratory acoustic stimulation predicts fetal pH in labor.

Vibratory acoustic stimulation was performed during labor in 188 instances 60 seconds before fetal scalp puncture was done to determine fetal scalp blood pH. The fetal heart rate response was recorded for both vibratory acoustic stimulation and fetal scalp puncture. No instance of fetal acidosis occurred in the presence of an acceleration to either vibratory acoustic stimulation or fetal scalp puncture. Vibratory acoustic stimulation was more likely to elicit an acceleration than fetal scalp puncture in the nonacidotic fetus. Vibratory acoustic stimulation is less invasive and may be used in some instances in which fetal scalp blood puncture for pH determination is technically impossible.