Olsen Twins

Consequently, if twins are monoamniotic that means that the two babies will be sharing a placenta and as a result, due to the small capacity of sharing a sac, the umbilical cord has an increased chance of being tangled around the babies. Because of this, there is an increased chance that the newborns may be miscarried or suffer from cerebral palsy due to the lack of oxygen.
Monoamniotic twins occur when the split takes place after the ninth day after fertilization.
• Conjoined twins
When the division of the developing zygote into 2 embryos occurs, 99% of the time it is within 8 days of fertilization.