بسم الله الرحمن الرحيم

Repeated Doses of Antenatal Repeated Doses of Antenatal Corticosteroids Corticosteroids

for Women at Risk of Preterm for Women at Risk of Preterm BirthBirth

Ahmed Alaa el dinAhmed Alaa el dinAssistant Lecturer of OB/GYNAssistant Lecturer of OB/GYN

Cairo UniversityCairo University

Introduction Preterm birth is a leading cause of perinatal death and

disability and is an important public health problem globally.

Administration of corticosteroids to mothers before preterm delivery significantly reduces perinatal morbidity and mortality.

Complications of preterm birth include:-Respiratory distress.-Intraventricular hemorrhage.-Periventricular leukomalacia.-Necrotizing enterocolitis.-Need for mechanical ventilation & admission to NICU.-Perinatal death.

Mechanism of Action of Antenatal

Corticosteroids

A. Respiratory Action Antenatal corticosteroid therapy leads to architectural

and biochemical changes that improve both lung mechanics and gas exchange. These changes are primarily the result of accelerated morphologic development of type 1 and type 2 pneumocytes. Type 1 pneumocytes are responsible for gas exchange in the alveoli, while type 2 pneumocytes are responsible for production and secretion of surfactant.

Antenatal corticosteroids also alter production of surfactant binding proteins and enhance fetal lung antioxidant enzymes.

However, for these changes to occur the lungs need to have reached a stage of development that is biologically responsive to corticosteroids.

B. Circulatory Action

Antenatal corticosteroid therapy improves circulatory stability in preterm neonates, resulting in less intraventricular hemorrhage and necrotizing enterocolitis.

Rationale for

Repeating antenatal

corticosteroids

Rationale for Repeating antenatal corticosteroids

The biologic rationale for repeating antenatal corticosteroid therapy is based upon the observation that biochemical stimulation of surfactant production appears to be reversible in cell culture models i.e. surfactant protein mRNA levels decline to control levels after cortisol is removed.

However, other beneficial effects, such as cytostructural maturation, persist after steroid exposure is withdrawn.

Effective Antenatal

Corticosteroid Regimens

Corticosteroid Regimens Corticosteroid regimens shown to be effective include:

betamethasone 12 mg intramuscularly, 2 doses 24 hours apart; or dexamethasone 6 mg intramuscularly 4 doses 12 hourly.

Benefits were found when treatment was started between 26 and 35 weeks of gestation, and for babies born 1–7 days after commencing treatment.

No benefits were demonstrated for treatment commenced, or infants born, before 26 weeks of gestation, nor for those born more than seven days after treatment.

Corticosteroid Regimens Some studies showed that betamethasone is associated

with lower incidence of RDS compared to dexamethasone.

Dexamethasone is associated with lower incidence of intraventricular hemorrhage, but with higher incidence of puerperal sepsis (especially if taken orally).

Advantages &

Disadvantages of

Repeated Antenatal

Corticosteroids

Advantages Repeated doses are associated with better neonatal lung

function than single course of corticosteroids, particularly among infants delivered before 32 weeks of gestation.

Also, less need for mechanical ventilation, continuous positive airway pressure, and surfactant use. There was also a reduction in the frequency of pneumothorax.

However, there is NO SIGNIFICANT BENEFIT in reduction of severe respiratory distress syndrome, grade III or IV intraventricular hemorrhage, chronic lung disease or periventricular leukomalacia.

Disadvantages Repeated doses are associated with lower birth weight

than the single course, and appear to cause IUGR.

However, it was found that repeating a SINGLE RESCUE DOSE or COURSE, does not affect fetal growth.

Some studies reported increased incidence of cerebral palsy.

Regarding late term effects, some studies showed affection of neurological development in early childhood.

Disadvantages In animals: studies have shown decreased brain size,

altered nerve growth, a delayed rate of myelination, altered retinal development, a decrease in the number of neurons and a dose-dependent degeneration of neurons in the hippocampus. Also it may be associated with increased incidence of hypertension.

Recommendations

Recommendations We recommend repeating a SINGLE RESCUE DOSE or

COURSE of antenatal corticosteroids only in cases who have passed 7 days since initial administration & are still at risk of preterm labor.

Thank

you