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Monochorionic twins
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<p>Monochorionic twins are <a href="/facts/Monozygotic/9QSssff4">monozygotic</a> (identical) <a href="/facts/Twins/9QSssff4">twins</a> that share the same <a href="/facts/Placenta/7XUoks1b">placenta</a>. If the placenta is shared by more than two twins (see <a href="/facts/Multiple_birth/bVVVhRvs">multiple birth</a>), these are monochorionic multiples. Monochorionic twins occur in 0.3% of all pregnancies. Seventy-five percent of <a href="/facts/Monozygotic/9QSssff4">monozygotic</a> twin pregnancies are monochorionic; the remaining 25% are <i>dichorionic diamniotic</i>. If the placenta divides, this takes place before the third day after <a href="/facts/Fertilization/g8u3UKzF">fertilization</a>. </p>