Alemci - you ask 'would it have been so awful if one of the children had caught it?' Well - yes, it might have been. Children can die of chicken pox - it's rare, but it happens. Chicken pox is thought to be responsible for one-third of all stroke cases in children. According to some american statistics I found, chicken pox has a mortality rate of 0.00002% in children under a year and 0.00008 in infants - very small, I do realise, but children have died of complications of chicken pox.
Or a child might have caught it and whilst infectious but before the spots showed, could have infected a pregnant woman, possibly causing congenital defects, such as:
Damage to brain: encephalitis, microcephaly, hydrocephaly, aplasia of brain
Damage to the eye: optic stalk, optic cup, and lens vesicles, microphthalmia, cataracts, chorioretinitis, optic atrophy
Other neurological disorder: damage to cervical and lumbosacral spinal cord, motor/sensory deficits, absent deep tendon reflexes, anisocoria/Horner's syndrome
Damage to body: hypoplasia of upper/lower extremities, anal and bladder sphincter dysfunction
Skin disorders: (cicatricial) skin lesions, hypopigmentation
Before 20 weeks pregnant, there is a 1-3% chance of the baby developing such complications if the mother gets chickenpox, and this percentage falls after 20 weeks.
If a baby is infected late on in pregnancy, or when newborn, this is neonatal varicella, and can be a severe infection - it can cause pneumonia or other serious complications.