Twins do have a **higher risk of cerebral palsy (CP)** compared to singletons, primarily due to factors associated with twin pregnancies such as **premature birth, low birth weight, and complications unique to multiple gestations**. Cerebral palsy is a group of permanent movement disorders caused by brain injury or abnormal brain development, often linked to events around the time of birth.
**Prematurity and Low Birth Weight as Key Risk Factors**
One of the strongest risk factors for cerebral palsy is **premature birth**, especially before 28 weeks of gestation. Nearly 60% of twin pregnancies result in birth before 37 weeks, which is considered premature[1]. Premature babies are significantly more vulnerable to brain injuries that can lead to CP. Research shows that between 33% and 50% of all cerebral palsy cases occur in premature infants[1]. Babies born extremely preterm (24 to 27 weeks) have up to a 15% chance of developing cerebral palsy[1].
Low birth weight, often accompanying prematurity, also increases the risk. Babies weighing less than 2,500 grams (5.5 pounds) at birth are classified as low birth weight and are more prone to complications such as respiratory distress syndrome, infections, and hypoxic-ischemic encephalopathy (HIE), all of which can contribute to brain injury and CP[1].
**Twin Pregnancy-Specific Risks**
Twin pregnancies are inherently high risk. Besides prematurity and low birth weight, twins face additional complications that can increase the risk of cerebral palsy:
– **Intrauterine Growth Restriction (IUGR):** One or both twins may not grow adequately in the womb, leading to oxygen deprivation and brain injury[1].
– **Twin-to-Twin Transfusion Syndrome (TTTS):** This condition affects about 10-15% of monochorionic (sharing one placenta) twins, where blood flow between twins is unbalanced. TTTS can cause severe complications including fetal death and neurological damage[3][4]. Surgical interventions like fetoscopic laser photocoagulation can help, but the condition still poses risks for brain injury.
– **Perinatal Arterial Ischemic Stroke (PAIS):** Studies have identified PAIS in about 1.5% of twin pairs born before 35 weeks, a type of stroke that can cause cerebral palsy[5][6].
– **Prolonged labor and delivery complications:** Twins are more likely to experience difficult labor, which can lead to oxygen deprivation and brain injury if not managed promptly[1].
**Hypertensive Disorders and Other Maternal Factors**
While hypertensive disorders of pregnancy (such as preeclampsia) are linked to some neurodevelopmental disorders, recent large meta-analyses have found **no significant direct increase in cerebral palsy risk** from maternal hypertension once factors like gestational age and birth weight are accounted for[2]. This suggests that the increased CP risk in twins is more strongly related to prematurity and growth issues rather than maternal hypertension itself.
**Why Twins Are at Higher Risk: A Summary of Mechanisms**
– **Prematurity:** Twins are more likely to be born early, and prematurity is the leading risk factor for CP.
– **Low birth weight:** Often a consequence of prematurity or growth restriction, increasing vulnerability to brain injury.
– **Placental complications:** Shared placentas in monochorionic twins can cause TTTS and uneven blood supply, leading to brain damage.
– **Birth complications:** Difficult labor and delivery increase the chance of oxygen deprivation.
– **Neonatal complications:** Premature twins are more prone to infections and respiratory problems that can contribute to brain injury.
**Preventive and Management Strategies**
Because of these risks, twin pregnancies require **specialized, high-risk obstetric care** with close monitoring for sign
