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Risks and complications of IVF treatment

Information on the maternal and fetal risks associated with multiple pregnancy.


Why are multiple pregnancies a problem?

If all twins, triplets, and quads were born as healthy as singletons there would not be any concerns. Unfortunately, multiple pregnancies have much higher risks than singletons for the fetuses and also for the mother. The risk of these complications arising must be balanced against the number of embryos transferred and the corresponding increase in success rate.

Maternal risks associated with multiple pregnancy

  • Miscarriage
  • Hemorrhage
  • Pregnancy induced high blood pressure
  • Pre-eclampsia occurs three to five times more frequently
  • Diabetes
  • Anemia
  • Polyhydramnios (excessive amounts of amniotic fluid that surrounds the fetus)
  • Caesarean section is often needed in twin pregnancy, and almost always required for triplets or more
  • Prolonged hospitalization resulting in higher cost of medical care

Fetal complications associated with multiple pregnancy

  • Preterm delivery. Preterm delivery is defined as delivery before 37 weeks completed. The average length of a pregnancy is 39 weeks for a single pregnancy, 35 weeks for twins and 33 for triplets. Preterm delivery occurs over 50% in twin pregnancy and in 90% of triplets. The proportion of twins and triplets delivering before 30 weeks pregnancy is around 7% and 15% respectively. These babies are more likely to suffer serious, lifelong, health problems, such as cerebral palsy and disability. The risk per pregnancy of producing a child with cerebral palsy is 8 times greater in twin pregnancies and 47 times greater in triplet pregnancies than in singleton pregnancies.
  • Multiple pregnancies have a four-fold increase in the rate of low birth weight compared to single pregnancy. The risk of lifelong disability is over 25% for babies weighing less than 1 Kg.
  • Stillbirth rates and neonatal death rates are higher for multiple pregnancies compared to singletons. For example, for a single birth the incidence is less than 1%, for twins 4.7% and for triplets 8.3%.
  • Birth defects are twice as common as in single birth.
  • A higher risk of Downs Syndrome
  • Increased risk of psychiatric conditions. Babies born before 32 weeks are at increased risk of bipolar disorders, depression and psychosis (Nosarti et al BMJ 2012).
Week of pregnancy 23 24 25 26 27 28
Moderate to severe handicap 65% 50% 40% 20% 15% less than 10%
Survival rate 15% 45% 60% 75% 80% 90%

An enquiry into quality of care and its effect on the survival of babies born at 27-28 weeks. CESDI Project 27/28, 2003

EPICure study, New England Journal of Medicine, 2005

Other problems

Multiple pregnancy is associated with more sickness, fatigue, heartburn, lack of sleep and financial difficulties. A recent American study reported adjusted total healthcare cost of around five times higher for twin deliveries compared to singleton deliveries and triplets was around 20 times higher.

Monozygotic (Identical) and Dizygotic (Non-identical) twins

Twins born as a result of two embryos implanted are usually non-identical. However, in about 4% of cases they can be identical as one embryo may fail to implant, while the second divides into two.

What does Mono Chorionic Diamniotic twins (MCDA) and Mono Chorionic Mono Amniotic twin mean (MCMA) ?

Mono chorionic twin mean that both babies share one placenta (afterbirth). These are identical twins and they are less common that non identical twins. In most identical twins, each baby have his own or her own separate sacs of fluid (MCDA). But less than 1 percent of the these identical twins the two babies share a sac (MCMA). The perinatal mortality risk among monozygotic twins has been reported to be two to three times higher than the risk among dizygotic twins. The problems associated with sharing placenta include feral growth restriction and Twin to Twin transfusion Syndrome. The rate of monozygotic twins increases with the use of ovulation induction, assisted hatching and ICSI.

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