QuestionSBA
QuestionChoice
This would be a very early delivery and would only be considered if there were concerns over foetal compromise and a careful discussion as part of a multidisciplinary team regarding the benefits and risks. There is no history suggesting this; therefore, the current recommendation for dichorionic diamniotic twins would be a delivery around 37  weeks.
53046
e
35–36 weeks
QuestionChoice
The lambda sign on ultrasound indicates a dichorionic diamniotic twin pregnancy. They each have their own placenta and amnion. The [current guidance](https://www.nice.org.uk/guidance/ng137/resources/twin-and-triplet-pregnancy-pdf-66141724389829) recommends delivery around 37 for this type of twin pregnancy. Earlier delivery may be necessary depending on how the pregnancy progresses but this is not routinely performed.
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a
37 weeks
QuestionChoice
The lambda sign on ultrasound indicates a dichorionic diamniotic twin pregnancy. They each have their own placenta and amnion; 39–40 weeks would be preferred gestation period for a medically unremarkable singleton pregnancy.
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c
39–40 weeks
QuestionChoice
As the gestation of a singleton passes 40 weeks, there can be concerns regarding the risk of foetal compromise and stillbirth; therefore, induction is discussed and offered. These risks would be higher in a twin pregnancy; therefore, induction would be offered even earlier.
53045
d
41 weeks
QuestionChoice
The lambda sign on ultrasound indicates a dichorionic diamniotic twin pregnancy. They each have their own placenta and amnion. The current guidance recommends delivery at around 37 for this type of twin pregnancy. Earlier delivery may be necessary depending on how the pregnancy progresses but this is not routinely performed. Women with monochorionic diamniotic pregnancies are offered delivery at 36–36+6 weeks due to these pregnancies being at higher risk, such as of twin–twin transfusion syndrome.
53043
b
36 weeks
QuestionComment
Women with dichorionic twin pregnancies should be offered elective birth from 37 weeks 0 days.

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QuestionComment
no shi sherlock, that's literally the answer 
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# Summary


Twin pregnancies are classified according to three main criteria: zygosity, chorionicity, and amnionicity. Dizygotic twins, or non-identical twins, result from the fertilisation of two distinct eggs by two different sperm cells, while monozygotic twins, or identical twins, occur when a single egg fertilised by a single sperm splits. Monozygotic twins are at a higher risk of certain complications, requiring careful monitoring during pregnancy.

# Types of twins

Twin pregnancies can be classified according to the zygosity, chorionicity and amnionicity.

- Monozygotic twins (identical) result from fertilisation of one egg and one sperm.

  - Depending on when the fertilised egg has split the twins maybe:

    - Dichorionic and diamniotic (two different sacs)
    - Monochorionic and diamniotic (same outer sac, two inner sacs)
    - Monochorionic and monoamniotic (same sacs)

  - Monozygotic twins are at increased risk of certain complications (e.g. twin-to-twin transfusion syndrome) and must be monitored more carefully during pregnancy than dizygotic twins.

- Dizygotic twins (non-identical) result from fertilisation of two different eggs with two different sperms. Dizygotic twins are all dichorionic and diamniotic (two separate outer and inner sacs) and have separate placentas.

# Epidemiology

In general about two thirds of twins conceived naturally are dizygotic and one third are monozygotic.
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Twin pregnancies
Topic
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Obstetrics
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In dichorionic diamniotic twin pregnancies, delivery is typically advised around 37 weeks to optimise outcomes for both foetuses.
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Normal pregnancy and antenatal care
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Obstetrics and gynaecology
A 30-year-old woman presents to secondary care for her second antenatal ultrasound scan. The scan shows two foetuses and the presence of the lambda sign.

Which of the following will be the advised delivery period?
a