Multiple gestation, a pregnancy with two or more fetuses, is considered a high-risk pregnancy. This is due to physiological demands on the mother and the complex shared environment. Understanding these risks is important for individuals expecting multiples, highlighting the need for specialized prenatal care and monitoring. More than one baby increases complications for both the pregnant individual and infants.
Elevated Maternal Health Risks
Multiple gestations place increased demands on the mother’s body, leading to more health complications. This strains multiple organ systems. This burden often manifests as conditions like gestational hypertension and preeclampsia, where blood pressure rises and affects organ function. These conditions are more common and severe, sometimes requiring early delivery.
Preterm labor and birth are more prevalent. The uterus, stretched by multiple fetuses and amniotic fluid, may begin contractions prematurely. This can lead to babies born before 37 weeks, a concern for newborn health. The mother also requires resources, making her susceptible to anemia due to increased blood volume and iron demands.
Gestational diabetes, characterized by high blood sugar, is another increased risk. The placenta(s) produce hormones that can interfere with insulin action, leading to glucose intolerance. Careful management is required to prevent complications for the mother and fetuses. The larger uterine size also increases the likelihood of polyhydramnios, excessive amniotic fluid.
After birth, the overdistended uterus may struggle to contract effectively, increasing the risk of postpartum hemorrhage. This excessive bleeding can be a serious complication requiring immediate medical intervention. Finally, complexities and complications often necessitate a Cesarean section. This procedure carries risks, including infection, blood loss, and longer recovery times.
Elevated Fetal and Neonatal Health Risks
The womb’s confined environment, shared by multiple fetuses, contributes to elevated risks for babies. Preterm birth, a direct consequence, increases the likelihood of underdeveloped organs in newborns. Premature babies may have immature lungs, brains, and digestive systems, requiring specialized care. This immaturity often leads to higher NICU admission rates for extended periods.
Low birth weight and intrauterine growth restriction (IUGR) are common. Each fetus may not receive adequate nutrition and space, resulting in smaller babies. This can lead to health challenges in infancy and later in life. Respiratory distress syndrome, caused by underdeveloped lungs, is common among preterm multiples.
The incidence of congenital anomalies, or birth defects, is also higher. Genetic predispositions and the unique developmental environment may play a role. These anomalies can range from minor to severe, potentially affecting organ systems. Increased vulnerability of preterm infants, combined with oxygen deprivation or brain bleeds, elevates the risk of cerebral palsy.
Cerebral palsy affects movement, balance, and posture, resulting from abnormal brain development or damage. Challenges of multiple gestations, including higher rates of prematurity and low birth weight, contribute to this increased risk. Overall, the delicate balance within a multiple pregnancy often creates a challenging environment for fetal development and neonatal outcomes.
Specific Complications Unique to Multiple Pregnancies
Beyond general risks, certain complex complications are exclusive to or more prevalent due to the unique shared environment. Twin-to-Twin Transfusion Syndrome (TTTS) is a severe condition affecting monochorionic twin pregnancies, where twins share a single placenta. In TTTS, abnormal connections between blood vessels in the shared placenta cause one twin (donor) to pump blood to the other (recipient).
This unequal blood flow can lead to health issues for both twins: the donor becomes anemic and smaller, while the recipient receives too much blood, leading to fluid overload and heart strain. Another condition, selective fetal growth restriction (sFGR), also occurs in monochorionic pregnancies when one twin grows slower. This often results from an unequal sharing of the placenta, where one fetus has a smaller or less efficient portion.
Twin Reversed Arterial Perfusion (TRAP) sequence is a rare but severe complication, seen in monochorionic pregnancies. In TRAP sequence, one twin develops normally, while the other has a severely malformed body, often lacking a heart or upper body structures. The normally developing twin pumps blood to the malformed twin through reversed blood flow, placing a burden on the healthy twin’s heart, potentially leading to heart failure.
In monoamniotic pregnancies, where twins share a single placenta and amniotic sac, there is a heightened risk of cord entanglement. The babies can move freely within the shared sac, increasing the chance of their umbilical cords becoming intertwined, restricting blood flow and oxygen. Additionally, multiple pregnancies have a higher risk of miscarriage or fetal demise, sometimes manifesting as “vanishing twin syndrome” where one fetus is reabsorbed early. Co-twin demise, the loss of one twin later in pregnancy, can also occur, posing risks to the surviving twin and mother.