Do twins share the same placenta?
Fraternal (non-identical) do not share the same placenta as they
are two babies formed from two eggs and two sperm. If they implant
close together they may appear to be one placenta, but they are
not. Identical twins formed from one egg and one sperm may split at
any stage from the two cell right up to late in embryonic
development which produces conjoined (Siamese) twins. The later in
embryonic development the split occurs the more likely they are to
share a placent.