Variability in the baseline fetal heart rate(FHR) is increasing attention as an indicator of the intrauterine fetal condition and correlated with good fetal outcome Regardless of the presence of absence of decelerations, FHR tracings with normal
variability are associated with higher cord blood pH and better Apgar scores than are tracings with decreased variability. However, the analysis of FHR tracings is subjective and visual interpretation of these tracings has proven controversial.
To
avoid
the documented inter- and intra-observer variation in the interpretation of fetal heart rate tracings, we used the objective means of computer analysis.
Intravenous magnesium sulfate is currently widely used both as a tocolytic and as an anticonvulsant in patients with preterm labor or preeclampsia, respectively. The possible effect of MgSO4 on fetal heart rate and behavior, however, have not
been
throughly investigated. Previous studies regard the effect of MgSO4 on fetal heart variability have shown conflicting results.
Thirty-one women diagnosed with preeclampsia and twenty-nine women diagnosed with preterm-labor who were no receive magnesium sulfate for seizure prophylaxis and uterine contraction were recruited. Exclusion criteria included delivery anticipated
within
2 hours, gestational age lee then 29 weeks, abnormal fetal testing growth retardation, multiple pregnancy, premature rupture of membrane, abnormal amniotic fluid volume, and use of illicit durg or medication.
Four grams of magnesium sulfate in 100 ml 0.9% saline was administered intravenously over 20 minutes, followed by a continuous infusion of 2 gm/hour, and 1 gm/hour in creased ever 30 mminutes if needed, till serum magnesium concentration is 6~8
mg/L. A
cardiotocogram analysis computer system was used analyze various elements of the fetal rate pattern before and after following magnesium sulfate loading for 1 hour. No other medications were administere. For each time interval, each parameter on
FHR
tracing were measured and printout was done.
We concluded that there were a statisticaly significant decrease in short-term variability(6.5±1.28 versus 5.9±1.04 ms p=0.0125) and long-term variability(33±4.42) versus 28±4.17 ms p=0.0009). Baseline fetal heart rate did not change
significantly
after magnesium sulfate was administered.
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