Betamethasone is a corticosteroid medication given during pregnancy when there is a high risk of preterm delivery. The treatment is intended for situations where a baby might be born before its organs, particularly the lungs, are ready to function outside the womb. It is a synthetic version of a naturally occurring hormone that helps prepare the fetus for an early birth.
Purpose of Antenatal Corticosteroids
The primary reason for administering antenatal corticosteroids like betamethasone is to accelerate fetal organ maturation, with the most direct impact on the lungs. The medication stimulates the fetal lungs to produce surfactant, a substance that lines the air sacs (alveoli). Surfactant reduces surface tension and prevents the alveoli from collapsing when an infant exhales.
Without sufficient surfactant, premature infants are at high risk for Respiratory Distress Syndrome (RDS), a condition that makes breathing difficult. By increasing surfactant production, betamethasone reduces the likelihood and severity of RDS, giving the newborn a better chance of breathing effectively after delivery.
Administration and Timing
Betamethasone is administered to the mother through two injections into a large muscle, such as the thigh or buttock. The medication travels through the mother’s bloodstream, crosses the placenta, and reaches the fetus. This method ensures the fetus receives the medication’s benefits before birth.
The standard protocol involves two 12 mg doses given 24 hours apart, though the interval may be shortened to 12 hours if delivery is imminent. This treatment is recommended for pregnant women between 24 and 34 weeks of gestation who are at high risk of delivering within the next seven days. The timing maximizes the medication’s benefits, which peak when delivery occurs between 24 hours and seven days after the final dose.
Impact on Newborn Health
Administering betamethasone before a preterm birth leads to several positive health outcomes for the newborn. The primary benefit is a reduced risk and severity of Respiratory Distress Syndrome (RDS). This allows many premature infants to breathe more easily and lessens their need for intensive respiratory support.
Beyond lung development, the treatment has protective effects on other systems. Betamethasone lowers the risk of intraventricular hemorrhage (bleeding in the brain’s ventricles) by up to 46%. It also helps mature the gastrointestinal tract, decreasing the incidence of necrotizing enterocolitis (NEC) by as much as 54%. NEC is an inflammatory condition that can destroy an infant’s intestinal tissue.
These combined effects decrease overall neonatal mortality and the need for admission to intensive care. By preparing multiple organ systems for early birth, betamethasone provides a defense against common complications of prematurity, improving both immediate survival and long-term health.
Associated Risks and Considerations
For the mother, side effects from a single course of betamethasone are generally mild and temporary. Common effects include pain at the injection site, facial flushing, and sleep disturbances. A temporary increase in blood sugar levels is also possible, which requires careful monitoring for individuals with gestational or pre-existing diabetes.
For the infant, the benefits of a single course are considered to outweigh the risks. Temporary changes may be observed, such as a brief reduction in fetal movement or heart rate variability. While a single course is standard, repeated courses are not routinely recommended, as some studies link them to lower birth weights or reduced head circumference.