Twins, Birth Injuries, and Hypoxic-Ischemic Encephalopathy (HIE)

A twin pregnancy is a high-risk condition that increases the risk of almost every pregnancy complication. Twins are more likely to have a brain injury called hypoxic-ischemic encephalopathy (HIE), which can cause lifelong problems such as cerebral palsy, seizure disorders, and developmental delays. Twins must be closely monitored throughout pregnancy and during labor and delivery. The most serious risks of a twin pregnancy are premature birth and intrauterine (fetal) growth restriction (IUGR/FGR), which can play major roles in birth injuries. Because twin pregnancies are high-risk conditions, mothers are often referred to maternal-fetal specialists (MFMs) for specialized care.

What Is Hypoxic-Ischemic Encephalopathy (HIE)?

Hypoxic-ischemic encephalopathy (HIE) is a brain injury caused by insufficient oxygen and blood flow to the baby’s brain. Problems with the placenta, uterus (womb), and umbilical cord are common causes of oxygen deprivation in a baby. Premature birth, when combined with oxygen deprivation, can also cause HIE. In premature babies,  oxygen deprivation typically causes a brain injury called periventricular leukomalacia (PVL). Hypoxic-ischemic encephalopathy usually involves damage to the basal ganglia, cerebral cortex, or watershed regions of the brain, but it sometimes also includes PVL.

What Are the Long-Term Effects of HIE?

Hypoxic-ischemic encephalopathy and periventricular leukomalacia often evolve into permanent brain damage. HIE and PVL can cause the following lifelong conditions:

What Complications are Associated with a Twin Pregnancy?

Twin pregnancies are associated with numerous complications, including:

  • Intrauterine growth restriction (IUGR): IUGR and FGR (fetal growth restriction) are terms that describe unborn babies with an estimated weight under the 10th percentile for their gestational age. This means the babies are smaller than they should be because they are not growing normally. IUGR has many causes but is most often caused by poor maternal nutrition, insufficient oxygen and nutrient supply for the baby, or placental insufficiency. Sometimes, a twin may be affected by selective IUGR due to unequal placental sharing. When twins share a placenta, their umbilical cords may implant anywhere. One baby may get less of a share of the placenta, and therefore an unequal share of oxygen and nutrients.
  • Preeclampsia: This is a multi-system disorder in the latter half of pregnancy, characterized by the onset of high blood pressure and either protein in the urine or end-organ dysfunction. Preeclampsia is dangerous for the baby because it often results in decreased blood flow in the placenta. Preeclampsia also increases the risk of placental abruption, and it can also turn into eclampsia (when mothers have seizures during labor).
  • Gestational hypertension: This is when high blood pressure is first detected after 20 weeks of pregnancy, but there is no protein in the urine or other indications of preeclampsia. Gestational hypertension can also cause decreased blood flow to the placenta.
  • Umbilical cord problems – intertwin cord entanglement: When twins’ cords become entangled, cord compression can occur, which restricts the blood flow going to the babies. Whenever blood flow is restricted, babies are at an increased risk of birth injuries like hypoxic-ischemic encephalopathy (HIE).
  • Twin to twin transfusion syndrome (TTTS)  in monochorionic (identical) twins: If the blood vessels of the two babies are connected, and one baby gets more blood flow than the other from the shared placenta, TTTS may occur. Treatments may include amniocentesis to drain excess fluid or laser surgery to seal off the connection between the blood vessels. Without prompt treatment, birth injuries are possible. In severe cases, both babies may die. Types of TTTS include twin anemia-polycythemia sequence (TAPS) and twin reversed arterial perfusion sequence (TRAP).
  • Death of one twin: If one twin dies, the surviving twin may have low blood pressure, restricted blood flow, anemia, and other problems that increase the risk of hypoxic-ischemic encephalopathy (HIE).
  • Preterm delivery/premature birth: This is one of the most serious complications of a twin pregnancy. Twins born prematurely are at in increased risk of numerous problems due to the immaturity of their body systems when superimposed with other problems, including brain bleeds (such as intraventricular hemorrhages [IVH]), hypoglycemia, sepsis, meningitis, respiratory problems, and hypoxic-ischemic encephalopathy.

Prenatal Testing and Monitoring to Prevent HIE and Birth Injury in Twins

Ultrasound Testing in Twin PregnanciesFetal Ultrasound - Preventing Birth Injuries

It is very important to do proper fetal monitoring  to check on the health of unborn twins. First, it is important to use routine ultrasound monitoring for multiple purposes during the first and second trimesters:

  • To confirm the presence of a twin pregnancy
  • To accurately estimate the twins’ gestational ages (which are needed to monitor for IUGR/FGR
  • To determine the type of twin pregnancy (identical vs. non-identical twins)
  • To help assess the health of identical twins’ shared uteroplacental circulation
  • To help identify serious pregnancy complications like TTTS
  • To help assess a baby’s fetal growth

The American College of Obstetrics and Gynecologists (ACOG) recommends ultrasounds when there are specific indications, such as when the size of the uterus is larger than expected. Ultrasounds during the first trimester can also detect abnormalities associated with birth injuries such as crown rump length (which is associated with TTTS).

Twins need to have much more frequent prenatal testing and very close surveillance. Each twin must be accurately identified over serial examinations. Medical professionals should document important features like the sites of placental implantation and the sites and types of placental cord insertion. Fetal growth assessment using ultrasound is very important to identify potential IUGR- ultrasounds should begin by the second trimester and continue throughout the third trimester.

Doppler Studies During Prenatal Care for Twins

More intensive fetal monitoring in the form of Doppler studies is needed if an ultrasound identifies growth discordance or IUGR, or if the mother has anemia. Doppler ultrasounds use sound waves to measure the amount and speed of blood flow through the blood vessels. They can be used to check the flow of blood in the umbilical cord and vessels of the uteroplacental circulation.

Other Prenatal Tests for High-Risk Twin Pregnancies

Prenatal testing includes:

Weekly prenatal testing should begin by 32 weeks of gestation (but earlier and more frequently if complications such as IUGR develop). Identical/diamniotic twins should be monitored by 16 – 18 weeks of pregnancy for early detection of TTTS. Medical professionals should perform assessments of amniotic fluid volume and fetal bladder. In these twins, Doppler studies should occur by 26 – 28 weeks for early detection of TAPS.

Early, Scheduled Delivery of Twins

Twins may need medical intervention as soon as they are born. These interventions can include resuscitation, cardiovascular support, respiratory support, blood transfusions, and even surgery. A pediatric team should be at the delivery so each baby has a team of medical specialists ready to quickly provide care. Blood products and other potential medical treatments should also be ready. Having a care team and treatments ready-to-go if needed  is one of the advantages of a scheduled early delivery.

In addition, twins can be given important medications in-utero to help prevent birth injuries and brain damage (steroids, magnesium sulfate), but these must be  given shortly before birth to be effective. Infection in the baby is also a major risk of spontaneous preterm birth. Preventing premature rupture of the membranes by having a scheduled delivery can decrease babies’ risk of infections like meningitis and sepsis, which can cause permanent brain damage.

If one or more of the babies isn’t getting enough oxygen and/or nutrients, an early delivery may be required to prevent the baby from experiencing HIE or other types of brain injury.

Specific Delivery Indications for Twins

Twins should be delivered early in the following situations:

Situation When to Deliver
Dichorionic-diamniotic twins (no further complications) 38 weeks
Dichorionic-diamniotic twins (with  further complications such as placental abruption, IUGR/FGR, preeclampsia, etc.) Weeks 36-37 or sooner
Monochorionic-diamniotic twins (no further complications) 34-37 weeks
Monochorionic-diamniotic twins (with further complications such as placental abruption, IUGR/FGR, preeclampsia, etc.) Closer to week 34 or sooner
Dichorionic-diamniotic or  monochorionic-diamniotic twins (with a single fetal death at or after 34 weeks) Immediate delivery
Dichorionic-diamniotic or  monochorionic-diamniotic twins (with a single fetal death before 34 weeks) Individualized timing of delivery based on maternal and fetal conditions. Complications such as IUGR/FGR may require prompt delivery even at less than 34 weeks.
Monochorionic-monoamniotic twins (no further complications) 32-34 weeks

When twins are affected by IUGR, prompt delivery is essential to prevent hypoxic-ischemic encephalopathy. It is important to emphasize that if any type of twins have high-risk conditions, delivery should usually take place at 32 – 34 weeks. High-risk conditions include, but are not limited to:

  • Oligohydramnios (an excess of amniotic fluid)
  • Maternal risk factors such as preeclampsia
  • Abnormal Doppler studies
  • Any long-term disease process

Regardless of gestational age, twins must have a prompt emergency C-section delivery if there is persistent abnormal fetal testing indicating imminent jeopardy of the baby.

Should I Have a Scheduled C-section or Labor Induction for My Twins?

Planned early delivery is almost always advisable to prevent HIE and other birth injuries in twin pregnancies. This planned delivery can occur either with a scheduled C-section or with a labor induction. Labor inductions can occur with:

  • Pitocin (synthetic oxytocin), which augments or induces labor
  • Misoprostol (Cytotec), which ripens and thins the cervix
  • Transcervical Foley catheter, which is a balloon used to open the cervix
  • Amniotomy, where artificially rupturing the amniotic membranes starts or increases contractions when the cervix is soft and slightly open

Each procedure carries with it attendant risks and advantages. Usually, medical professionals recommend early scheduled C-sections for twin births, though the timing may vary depending on the mother and baby’s health profiles. Medical professionals should thoroughly explain the risks and benefits of all procedures and medications to mothers in order to obtain informed consent.

Risks of Labor Induction for Twin Deliveries

Mothers should know that labor induction doesn’t always work as well as natural labor. There is a roughly 35-50% chance that a mother may end up needing a C-section after a labor induction, as labor through induction may sometimes fail to progress.

There are also risks involved in labor induction methods:

  • Pitocin and Cytotec can cause hyperstimulation and hypertonic uterus. In non-augmented labor, the uterus contracts in a pattern of contractions and relaxations, allowing the baby to get oxygen between contractions. With augmentation drugs, the uterus can either contract too strongly or too often, which means that placenta can’t ‘recharge’ with oxygen-rich blood for the baby. This puts babies at risk for oxygen deprivation injuries. Hyperstimulation can also increase the risk of the baby having a brain bleed or compressed umbilical cord.
  • Uterine rupture is a risk with Pitocin and Cytotec. Uterine rupture can cause severe blood loss, which can cause blood pressure in the baby to drop.

If a baby is being oxygen-deprived, the fetal heart rate monitor will begin to show nonreassuring heart tracings. When these tracings occur, the baby must be delivered right away – usually by emergency C-section – to prevent prolonged birth asphyxia and hypoxic-ischemic encephalopathy (HIE).

What to Do if Your Twins Had Birth Injuries

The first step whenever your child has a birth injury is to seek appropriate medical care, whether it is through your child’s pediatrician, a specialized developmental clinic, or other medical professionals. If you are worried that your children’s developmental delays, disabilities, or cerebral palsy stemmed from an error that a medical professional made – whether it was during prenatal care, labor, or delivery – it may be helpful to ask the birth injury attorneys at Reiter & Walsh PC to review your case. Case review is 100% free and confidential. The money from a birth injury verdict or settlement can be used to secure your children’s future, provide them with therapy and medical equipment, and cover the costs of medical care and accessible housing that existing insurance and assistance programs won’t cover.

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Video: Hypoxic-Ischemic Encephalopathy (HIE)