Multiples Flashcards
Incidence of multiple pregnancies
Accounts for 3% of live births
Prompt 2017
Potential complications of multiple pregnancy
- Pre-eclampsia is reported to be more frequent - Anaemia as two or more fetuses make greater demands on the mother's stores of iron and folic acid - Acute polyhydramnios can occur and may be associated with fetal abnormalities but with monochorionic twin pregnancies it is more likely to be due to twin to twin transfusion syndrome. - Twin to twin transfusion syndrome (TTTS) - Preterm labour - APH due to placenta praevia more common due to large placental site and abruption may occur following ARM (Mayes 2012)
What is twin to twin transfusion syndrome?
Can be acute or chronic and occurs in approximately 15% of monochorionic diamniotic twin pregnancies. It arises because of unequal blood flow through placental anastomoses from one fetus to the other. The donor twin transfuses blood via arteriovenous anastomoses of the placenta to the recipient twin.
(Mayes 2012)
Complications of twin to twin transfusion syndrome
Results in growth restriction, oligohydramnios and anaemia in the donor twin
The recipient twin can develop polycythaemia with circulatory overload (hydrops).
The fetal and neonatal mortality is high
(Mayes 2012)
Why is the rate of conception of multiple pregnancies likely to be higher than records suggest?
Due to the vanishing twin syndrome where USS shows that although there may be two or more fetal sacs in the first few weeks, some fetuses may die during the first
(Mayes 2012)
Stillbirth rate in twins compared to singleton pregnancies
In the UK 2.42 per 200 twin births are delivered stillborn, compared to 1 in 200 singleton births
(TAMBA 2016)
Types of twins
Monozygotic = arise when a zygote divides into twi identical halves during the first 14 days after fertilisation. They will have the same genetic make up and will therefore be of the same sex
Dizygotic = twins result from the fertilisation of two separate ova by two separate sperm. They may be of the same or of different sex and not more genetically alike than any other siblings
(Mayes 2012)
Types of placenta and amniotic sacs in twins
Dichorionic = each baby has a separate placenta. Embryo divides within the first 3 or 4 days
Monochorionic diamniotic = both babies share a placenta but have separate amniotic sacs. Division occurs between 4 and 8 days
Monochorionic monoamniotic = both babies share a placenta and amniotic sac. Occurs between 9-12 days
(NICE 2011)
Zygosity determination
Means finding out whether or not twins/triplets are monozygotic. When a twin pregnancy is diagnosed an assessment of the chorionicity should be made by measuring the thickness of dividing membranes
(Mayes 2012)
What types of twins have a 3-5 times higher risk of perinatal mortality and morbidity?
Monozygotic twins
What advice should be given at first contact with twin mums?
- Antenatal and postnatal mental health and wellbeing - Antenatal nutrition - The risks, symptoms and signs of preterm labour and potential need for corticosteroids for fetal ling maturation - Likely timing and possible modes of delivery - Breastfeeding - Parenting (NICE 2011)
Screening of twins
There is a greater likelihood of Down’s syndrome in twins and triplet pregnancies. False positive rates are higher, there’s a greater likelihood of being offered invasive testing and complications from invasive tests
(NICE 2011)
Conjoined twins
Result from incomplete monozygotic division of the fertilized ovum. It is extremely rare, occurring in approximately 1.3 per 100,000 births
(Mayes 2012)
What percentage of twin pregnancies results in preterm birth?
60%
NICE 2011
When to offer uncomplicated women electives
Monochorionic twins = from 36+0 after a course of antenatal corticosteroids
Dichorionic = 37+0
(NICE 2011)
