Cm. Dwyer et al., THE EFFECT OF MATERNAL UNDERNUTRITION ON THE GROWTH AND DEVELOPMENT OF THE GUINEA-PIG PLACENTA, Journal of developmental physiology, 18(6), 1992, pp. 295-302
Fetal growth is known to be correlated with the size of the placenta a
nd the exchange surface area. Reduction in the growth of the materno-f
etal exchange surface areas may be a mechanism by which the effects of
maternal undernutrition on fetal growth are mediated. In the compact
placenta of the guinea pig the exchange surface is equivalent to the p
eripheral labyrinth. The effect of a 40% reduction in maternal feed in
take on the growth of the peripheral labyrinth was investigated in pre
gnant guinea pigs between gestational days 25 and 65. Fetal and placen
tal weights were significantly reduced in the last trimester by 32% an
d 38% respectively (P<0.01). Placental efficiency in early gestation w
as significantly impaired in restricted animals but equivalent to ad l
ib. fed controls by the last trimester. The volume of the peripheral l
abyrinth increased as a percentage of the total placental volume with
gestational age. Restricted placentae tended to be composed of a small
er volume of peripheral labyrinth tissue in early gestation. It is sug
gested that maternal undernutrition results in an impaired or delayed
expansion of the peripheral labyrinth in early gestation causing a red
uction in placental efficiency. By the last trimester the weight of th
e peripheral labyrinth of restricted animals was reduced by 33% (P<0.0
5). The weight of the peripheral labyrinth was also significantly corr
elated with fetal weight during the last trimester, suggesting that fe
tal weight is limited by the size of the peripheral labyrinth in the l
ater stages of gestation.