ok ..
the baby will be infected in both cases ..
but the difference is that the infection before the last week would give the mother a chance to develop a VZ-Ig
(varicella-zoster Immuno-globulins)
which will be able to be transmitted through the placenta to the baby and protect him/her
on the other hand, if the mother got infected at her last week of pregnancy, she wouldn't have enough time to produce her VZ-Ig's and the baby will be unprotected
and the newborn will develop all those features of CVS
(congenital varicella syndrome)
you can always give Z-Ig to the newborn as fast as u can diagnose the disease ..
so, this is what i know ..
u should always double check with the doctor or other sources such as books.
all the best,
HERO