Multiple pregnancy Flashcards
What is Multiple Pregnancy?
birth of more than 1 baby from a single pregnancy
What are the types of twin pregnancies?
- Monozygotic twins
- Dizygotic twins
Monozygotic twins can also be called?
Identical twins
Uniovular twins
Dizygotic twins can also be called?
Fraternal twins
Nonidentical twins
Binovular twins
What are Monozygotic twins?
refers to 2 embryos developing from 1 fertilized zygote
What are Dizygotic twins?
refers to 2 embryos developing from 2 distinct zygotes
Dizygotic twins are always classified as?
Dichorionic Diamniotic (DCDA)
Monozygotic twins can be classified as?
- Monochorionic Diamniotic (MCDA)
- Monochorionic Monoamniotic (MCMA)
- Dichorionic Diamniotic (DCDA)
- Conjoint twins
What is the most common type of Monozygotic twins?
Monochorionic Diamniotic
What is the least common type of Monozygotic twins?
Dichorionic Diamniotic
What is Chorionicity?
refers to the # of placenta (think chorionic plate of the placenta)
What is Amnionicity?
refers to the # of fetal membranes (think amniotic sac)
What is Zygosity?
refers to the # of ova
If the zygote splits < 4 days post-fertilization, you get?
Dichorionic Diamniotic twins
if the zygote splits between 4-8 days post-fertilization, you get?
Monochorionic Diamniotic twins
if the zygote splits between 8-14 days post-fertilization, you get?
Monochorionic Monoamniotic twins
if the zygote splits after 14 days, post-fertilization, you get
Conjoint twins
Why would Conjoint twins result, when the zygote splits after 14 days post-fertilization?
because: the primitive streak is fully formed after 14 days, so if the zygote splits at this point you would have incomplete splitting of the germinal disc
Why would Monochorionic Diamniotic twins result, when the zygote splits between 4 & 8 post-fertilization?
because: the chorion is fully formed between 4 & 8 days, so only 1 placenta would result. However the amniotic cavity is not yet formed, so 2 amniotic sacs would result.
Why would Monochorionic Monoamniotic twins result, when zygote splits between 8 & 14 days post-fertilization?
because the chorion and amniotic cavity are already formed between 8 & 14 days, so only 1 placenta and 1 amniotic sac would result.
Why would Dichorionic Diamniotic twins result, when the zygote splits before 4 post-fertilization?
because neither the chorion or amniotic sac is formed at the 8 cell stage, so 2 placentas & 2 amniotic sacs would result.
