Monozygotic twin pregnancy
Updates to Article Attributes
A monozygotic (MZ) twin pregnancy results from division of single zygote following fertilisation and share similar genetic materials. These twins are therefore always of the same gender.
Epidemiology
MZ twins account for approximately 30% of all twin pregnancies 1. The estimated incidence is at ~1 in 250 births with little racial variation for this sub type 3 (c.f dizygotic pregnancy).
Physiology
Depending on the time of division of the zygote, there can be many possibilities
- division at 1-4 days (morula) results in dichorionic-diamniotic twins (di-di) (DCDA) : 20% of monozygotic twin pregnancies
- division at 4-8 days (blastocyst) results in monochorionic-diamniotic twins (mono-di) (MCDA) : 75% of monozygotic twin pregnancies
- division at 1-2 weeks results in monochorionic-monoamniotic twins (mono-mono) (MCMA): 5% of monozygotic twin pregnancies
- division at > 2 weeks results in conjoined twins: <1% of monozygotic twin pregnancies
Related pathology
MonozygoticPrenatal diagnosis of chorionicity is important as monochorionic pregnancies have increased rates and severity of all types of obstetric complications when compared with dichorionic pregnancies. Monozygotic twins have higher rate of fetal anomalies although they tend to be discordant-only affecting one twin despite identical genetic makeup.
Monochorionic twin pregnancies share the one placenta and are therefore prone to haemodynamic complications such as:
- twin-twin transfusion
- twin reversed arterial perfusion sequence
- twin embolisation syndrome
- acardiac twin
- demise of co-twin
Monochorionic monoamniotic twins also carry additional cord related complications such as:
See also
-<p>A <strong>monozygotic (MZ) twin pregnancy</strong> results from division of single zygote following fertilisation. These twins are therefore always of the same gender.</p><h4>Epidemiology</h4><p>MZ twins account for approximately 30% of all twin pregnancies <sup>1</sup>. The estimated incidence is at ~1 in 250 births with little racial variation for this sub type <sup>3</sup> (c.f dizygotic pregnancy).</p><h4>Physiology</h4><p>Depending on the time of division of the zygote, there can be many possibilities</p><ul>- +<p>A <strong>monozygotic (MZ) twin pregnancy</strong> results from division of single zygote following fertilisation and share similar genetic materials. These twins are therefore always of the same gender.</p><h4>Epidemiology</h4><p>MZ twins account for approximately 30% of all twin pregnancies <sup>1</sup>. The estimated incidence is at ~1 in 250 births with little racial variation for this sub type <sup>3</sup> (c.f dizygotic pregnancy).</p><h4>Physiology</h4><p>Depending on the time of division of the zygote, there can be many possibilities</p><ul>
-</ul><h4>Related pathology</h4><p>Monozygotic twins have higher rate of fetal anomalies although they tend to be discordant-only affecting one twin despite identical genetic makeup.</p><p><a href="/articles/monochorionic-twin-pregnancy">Monochorionic twin pregnancies</a> share the one <a href="/articles/missing">placenta</a> and are therefore prone to haemodynamic complications such as:</p><ul>- +</ul><h4>Related pathology</h4><p>Prenatal diagnosis of chorionicity is important as monochorionic pregnancies have increased rates and severity of all types of obstetric complications when compared with dichorionic pregnancies. Monozygotic twins have higher rate of fetal anomalies although they tend to be discordant-only affecting one twin despite identical genetic makeup.</p><p><a href="/articles/monochorionic-twin-pregnancy">Monochorionic twin pregnancies</a> share the one <a href="/articles/missing">placenta</a> and are therefore prone to haemodynamic complications such as:</p><ul>
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