Maternal, but not fetal, administration of corticosteroids restricts fetal growth.
OBJECTIVE
Previous studies have shown that repeated doses of corticosteroids given to pregnant sheep improve postnatal lung function, but restrict fetal growth. Repeated administration of corticosteroids directly to the fetus also enhances postnatal lung function. The purpose of the present study was to investigate and characterize the relative effects on growth of repeated maternal and fetal treatments by study of body, organ, and placental weights.


METHODS
Date-bred pregnant sheep were given intramuscular betamethasone or saline to either the mother or fetus on three occasions at weekly intervals commencing at 104 days gestation, followed by cesarean section at 125 days. Twenty-two animals which had received three doses of betamethasone were compared with 21 which had received a single dose at 104 days and with 12 saline-treated controls.


RESULTS
Repeated maternal doses of betamethasone resulted in reductions in birthweight and weights of the placenta and major organs. Direct fetal injection did not affect birthweight, placental weight, placental/ birthweight ratio, or weights of the major organs with the exception of the liver.


CONCLUSIONS
Administration of repeated doses of betamethasone directly to the sheep fetus does not produce the growth-restricting effects induced by maternal administration and does not affect the placental/birthweight ratio.
Newnham
J P
JP
Department of Obstetrics, Women and Infants Research Foundation at King Edward Memorial Hospital, University of Western Australia, Perth, Australia. jnewnham@cyllene.edu.uwa.au
Evans
S F
SF
Godfrey
M
M
Huang
W
W
Ikegami
M
M
Jobe
A
A
D000305:Adrenal Cortex Hormones / Q000008:administration & dosage* / Q000009:adverse effects*; D000818:Animals; D001623:Betamethasone / Q000008:administration & dosage / Q000009:adverse effects; D001724:Birth Weight / Q000187:drug effects; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D005260:Female; D005333:Fetus / Q000187:drug effects*; D005938:Glucocorticoids / Q000008:administration & dosage / Q000009:adverse effects; D008431:Maternal-Fetal Exchange; D009929:Organ Size / Q000187:drug effects; D010920:Placenta / Q000033:anatomy & histology; D011247:Pregnancy; D012756:Sheep
D000305:Adrenal Cortex Hormones; D005938:Glucocorticoids; D001623:Betamethasone