Multiple Births Flashcards
What is the rate of twin births compared to triplet births?
About 30 per 1000 births are twins, while about 1 per 1000 births are triplets.
What are the two types of twin births?
Twin births can be identical (monozygotic), arising from a single fertilized egg (zygote), or non-identical (dizygotic), arising from two separate eggs.
How does the rate of non-identical twinning vary across different communities?
The rate of non-identical twinning varies from 10 to 40 per 1000 in different communities.
What factors increase the risk of non-identical twinning in women?
The risk of non-identical twinning increases in women over 35 years of age and in women receiving infertility treatment, as they both have a higher rate of polyovulation
What is the incidence of identical twins in all communities?
The incidence of identical twins is about 3 per 1000 births in all communities.
Do non-identical twins share the same placenta?
No, non-identical twins always have separate placentas.
What term describes the placentas of non-identical twins?
The placentas of non-identical twins are called dichorionic, as each placenta has its own chorion.
Can twin-to-twin shunts occur between dichorionic placentas?
No, there are never anastomoses between dichorionic placentas, so twin-to-twin shunts cannot occur.
What percentage of identical twins share a single placenta?
70% of identical twins share a single placenta, known as monochorionic placentas.
How is the type of placentation in identical twins determined?
The timing of the zygote split determines the type of placentation, with an early split resulting in dichorionic placentas.
What is the significance of dichorionic placentas in determining zygosity in twins?
With dichorionic placentas, the twins must be non-identical if one twin is male and the other female. However, about 30% of same-sex twins with dichorionic placentas will be identical, necessitating DNA testing for confirmation.
How is chorionicity determined in twins?
Chorionicity can be diagnosed by ultrasonography at 12 weeks of gestation. Thick dividing chorions indicate dichorionic placentas, while the absence of a chorion separating the placentas indicates identical twins.
What are the characteristics of a monochorionic placenta?
A monochorionic placenta usually has two amnions (monochorionic-diamniotic). If both twins are in a single amniotic sac (monochorionic-monoamniotic), there is an increased risk of umbilical cord entanglement and conjoint twinning.
Why are twins with a monochorionic placenta at risk of twin-to-twin transfusions?
Twins with a monochorionic placenta always have anastomoses and share the same blood pool, allowing for twin-to-twin transfusions.
How is chorionicity determined after delivery?
Chorionicity can be easily determined by examining the placenta after delivery.
What percentage of twins and triplets are born preterm?
50% of twins and 90% of triplets are born preterm.
What is the risk of major congenital abnormalities in identical twins compared to non-identical twins?
The risk of major congenital abnormalities is increased to 6% in identical twins, whereas it is only 3% in non-identical twins, which is the same risk as singletons.
Why is the risk of major congenital abnormalities higher in identical twins?
The higher risk in identical twins is attributed to monozygotic twinning, which is an abnormal event due to the splitting of a single zygote.
What is the cause of growth restriction in twins?
Growth restriction in twins is common due to the increased nutritional demand by two fetuses.
What is twin-to-twin transfusion syndrome (TTTS)?
Twin-to-twin transfusion syndrome (TTTS) occurs in monochorionic twins and results in a larger polycythaemic twin with polyhydramnios, who is the blood recipient, and a smaller anaemic twin with oligohydramnios, who is the blood donor.
How does TTTS differ in monochorionic and dichorionic twins?
In monochorionic twins, TTTS occurs due to twin-to-twin anastomoses, resulting in one twin becoming larger and the other smaller. In contrast, in dichorionic twins, there are no anastomoses, and the smaller, growth-restricted twin may have polycythaemia due to chronic hypoxia.
effects of polyhydramnios
heart failure due to fluid overload
What are some factors contributing to higher neonatal mortality and morbidity in multiple pregnancies?
Neonatal mortality and morbidity are higher in multiple pregnancies due to prematurity, growth restriction, congenital abnormalities, and complicated deliveries.
Why is it important to deliver twins in a hospital with facilities for newborn care?
Delivering twins in a hospital with newborn care facilities is crucial due to the higher risks associated with multiple pregnancies, ensuring prompt medical intervention if needed.
What challenges do parents of twins face in terms of breastfeeding and bonding?
Parents of twins may face challenges in breastfeeding and bonding with two or more infants simultaneously, requiring additional support and resources.
