Twins do have a higher risk of cerebral palsy (CP) compared to singletons, and this increased risk is largely linked to complications related to delivery and pregnancy, especially those associated with preterm birth and specific twin-related conditions. However, the relationship is complex and influenced by multiple factors.
**Cerebral palsy** is a group of permanent movement disorders caused by damage to the developing brain, often occurring before, during, or shortly after birth. Delivery complications such as hypoxic-ischemic encephalopathy (HIE), where the brain is deprived of oxygen and blood flow, are a leading cause of CP[5].
### Why Twins Have Higher CP Rates
1. **Preterm Birth and Low Birthweight**
Twins are much more likely to be born prematurely and with low birthweight compared to singletons. Preterm birth is a major risk factor for CP because the brain is more vulnerable to injury during early development. Studies show that preterm infants have a significantly higher incidence of CP[1][4]. Since twins have a preterm birth rate around 50% or higher, this alone increases their CP risk substantially.
2. **Twin-Specific Complications**
Certain complications unique to twin pregnancies further increase risks:
– **Twin-to-Twin Transfusion Syndrome (TTTS):** This condition occurs in about 10-15% of monochorionic (sharing one placenta) twins, where blood flow between twins is unbalanced. TTTS can cause severe fetal distress, growth problems, and even fetal death if untreated. The treatment involves fetoscopic laser surgery to sever abnormal blood vessel connections[2][3]. TTTS and its complications can lead to brain injury and increase CP risk.
– **Monochorionic Twins:** Twins sharing a placenta have higher risks of complications like TTTS and selective intrauterine growth restriction, both of which can compromise oxygen and nutrient delivery to the brain.
3. **Delivery Complications**
Twins are more likely to experience complicated deliveries, including:
– Malpresentation (e.g., breech position)
– Cord prolapse or compression
– Prolonged labor or emergency cesarean sections
These complications can cause hypoxia (oxygen deprivation) during birth, a known cause of CP[5].
4. **Infections and Inflammation**
Infections such as chorioamnionitis (infection of the fetal membranes) are more common in multiple pregnancies and have been linked to increased CP risk due to inflammatory damage to the fetal brain[7].
### What Does Research Say?
– A large systematic review and meta-analysis of over 29 million children found no direct increased likelihood of CP from hypertensive disorders of pregnancy after adjusting for gestational age and birthweight, highlighting the importance of prematurity and growth restriction as mediators[1]. This suggests that the increased CP risk in twins is more about prematurity and related complications than maternal hypertension itself.
– Preterm birth rates in women with cervical complications (which can be more common in twins) are around 48%, emphasizing the high prematurity risk in twin pregnancies[4].
– Hypoxic-ischemic encephalopathy (HIE), a major cause of CP, occurs in about 1.5 to 2.5 per 1,000 live births and is more frequent in complicated deliveries, which are more common in twins[
