Effect of interval from fetal corticosteroid treatment to delivery
on postnatal lung function of preterm lambs .
Ikegami, Machiko, Daniel H. Polk, Alan H. Jobe, John Newnham, Peter
Sly, Rolland Kohan, Robert Kelly.
Perinatal Laboratories, Harbor-UCLA Medical Center, Torrance, CA,
University Department of Obstetrics/Gynecology and Department of
Newborn Medicine, King Edward Memorial Hospital, Subiaco, Western
Australia, Western Australia
APStracts 2:0407A, 1995.
The effect of altering the interval from treatment to delivery on
postnatal lung function of the preterm, is unknown. We treated groups
of 8 to 10 singleton fetal sheep with 0.5 mg/kg betamethasone by
fetal injection and evaluated postnatal lung function 40 min after
preterm delivery at 123 d gestation 2 d after treatment or, at 128 d
gestation 2 d, 4 d, and 7 d after treatment relative to groups of 4
to 8 saline injected control animals. At 123 d, betamethasone
significantly improved PaCO2, dynamic thoracic compliance,
ventilatory efficiency index, and doubled lung gas volume relative to
a control group. Fetal treatment with betamethasone 2 d, 4 d, or 7 d
before delivery at 128 d also improved these same indicators of lung
function relative to controls, and the magnitude of the improvements
were the same for all indicators and independent of treatment to
delivery interval. Betamethasone suppressed the normal postnatal
increase in plasma cortisol after 2 and 4 d of exposure but not after
7 d of exposure. Betamethasone also increased fetal and postnatal T3
concentrations after 2 d exposure but not at 4 or 7 d. Although the
hormone effects were transient, postnatal lung functional responses
to betamethasone persisted over the 2 to 7 d interval from treatment
to delivery.
Received 6 March 1995; accepted in final form 7 September 1995.
APS Manuscript Number A243-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95