Effect of intravenous beta-sympathomimetic tocolysis on human fetal serum erythropoietin levels.
OBJECTIVE
The major stimulus for erythropoietin production is tissue hypoxia. We sought to investigate the relationship of beta-sympathomimetic administration for tocolysis and fetal serum erythropoietin.


METHODS
Umbilical cord blood was obtained from infants whose mothers received intravenous beta-sympathomimetic tocolysis and who were delivered at < or = 34 weeks' gestation. Serum erythropoietin was measured by radioimmunoassay. On the basis of the presumed 2- to 4-hour half-life of fetal erythropoietin, the infants were divided into two groups. In group 1 (n = 16) beta-sympathomimetic therapy was discontinued < 24 hours before delivery; in group 2 (n = 11) it was discontinued > or = 24 hours before delivery.


RESULTS
Group 1 fetuses had significantly higher erythropoietin levels than did group 2 fetuses (37.3 vs 13.9 mU/ml, p = 0.02). The duration of beta-sympathomimetic tocolysis and the maximum infusion rate were not different. The two groups did not differ in gestational age, birth weight, route of delivery, presence of labor, or duration of first or second stage of labor.


CONCLUSIONS
We speculate that intravenous beta-sympathomimetic tocolytic therapy stimulates fetal erythropoietin production by decreasing fetal oxygenation as a result of the reversible fetal metabolic effects of the tocolysis. These data suggest that beta-sympathomimetic tocolysis should be undertaken cautiously if fetal compromise is suspected, fetal well-being should be assessed carefully if tocolysis is undertaken, and treatment should be discontinued promptly if a clear benefit is not realized.
Rouse
D J
DJ
Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City.
Widness
J A
JA
Weiner
C P
CP
D004921:Erythropoietin / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005315:Fetal Diseases / Q000139:chemically induced; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000139:chemically induced; D007262:Infusions, Intravenous; D011247:Pregnancy; D013566:Sympathomimetics / Q000009:adverse effects / Q000494:pharmacology*; D015149:Tocolytic Agents / Q000009:adverse effects / Q000494:pharmacology*
D013566:Sympathomimetics; D015149:Tocolytic Agents; D004921:Erythropoietin