Steroids are usually given to pregnant women to benefit the baby in the following situations (ACOG):
- Pregnant women at 24 0/7 weeks – 33 6/7 weeks who are at risk of having premature delivery within the next 7 days
- Pregnant women at 34 0/7 weeks – 36 6/7 weeks of gestation at risk of having birth within seven days provided they did not receive steroids previously, and they don’t have chorioamnionitis
Steroid treatment course that we offer to women before delivery of the premature baby is often called: antenatal steroids.
Prematurity is defined as a birth before completed 37 weeks of gestational age. Premature birth poses a significant risk for a newborn baby. Preemie babies often have to remain in the NICU receiving treatment for respiratory problems and other issues associated with low birth weight and immaturity (my article on that topic).
Steroid treatment that we can give to a pregnant woman who is expected to deliver a premature baby is one of the very few measures available to us that can help the future baby.
Background information on steroids during pregnancy
In 1972, doctors discovered that a single dose of steroids given to the mother at risk of having a premature baby could decrease the incidence and severity of respiratory problems and mortality in the newborn (Source).
Numerous subsequent trials confirmed those findings and allowed doctors to decide on the type of steroids and dose of medications that should be used for this purpose. Over the years, we also found that steroids improve not only respiratory outcomes but many others. I will expand on that in the next section of this article.
To help the future baby, we can use two types of steroids: Bethametasone and Dexamethasone. Both are administered as an intramuscular injection. However, Bethametasone is given in 2 doses 24 hrs apart, and Dexamethasone should be delivered in four doses 6 hours apart.
When doctors looked at respiratory outcomes and survival in newborn babies in comparative trials, both steroids performed similarly. Therefore, it does not matter which steroid is chosen by your doctor.
It is believed that at least 24 hrs are needed for steroids to show positive effects in a baby. Therefore, if possible, the birth of the baby should be delayed by 24 hrs after the first dose of steroids.
In the past, we used to give several courses of steroid treatment to mothers. However, nowadays, we are more careful. We have some concerns about the effects of repetitive courses of steroids on the baby and mother. We may administer one dose or full second course if the previous steroid course was given at least 14 days ago, and the mother is still at below 34 weeks of gestational age.
If a woman is at more than 34 weeks of gestational age and she already had a previous steroid course, typically, she would not be offered another treatment.
Benefits of steroids for babies
Respiratory distress is the most common condition found in premature babies after birth.
The main benefits of maternal steroids for the baby are effects on its lungs. Steroids improve the structural and biochemical maturation of the lungs resulting in better lung mechanics and gas exchange. As a result, maternal steroids decrease the incidence and severity of respiratory distress in premature babies.
Pooled data from multiple research trials showed that prenatal steroids decrease the incidence of respiratory distress (RDS) by 34%, reduce the frequency of moderate and severe RDS by 41%, and decrease the need for mechanical ventilation in premature babies after birth by 32% (Source).
Decrease in mortality
Premature babies have an increased risk of death. That risk increases as gestational age at birth decreases. For example, about 40%-50% of babies born at 24 weeks will survive, whereas 90% or more will survive if they are born at 28 weeks of gestational age.
Antenatal steroids were found to decrease mortality in newborn babies by about 30%
Decrease in the incidence of Intraventricular Hemorrhage (IVH)
Premature babies are at risk of developing intraventricular hemorrhage. Due to fragile blood vessels in the brain and fluctuations in blood pressure, some babies develop bleed in the areas of the brain called ventricles.
The presence of intraventricular hemorrhage increases the risk of future developmental problems in the baby.
The administration of antenatal steroids to the mother is associated with a 45% decrease in the incidence of IVH in babies.
Decrease in the incidence of Necrotizing Enterocolitis
Necrotic enterocolitis (NEC) is a severe inflammatory and infectious disease of the GI tract that may affect some premature babies. Affected babies frequently need prolonged antibiotic treatments, sometimes surgery. Some of the babies do not survive it.
If a mother was given steroids before the delivery, the incidence of NEC is likely to be 50% less.
Potential risks of steroids
Giving steroids to mothers who are at risk of delivering a premature baby is reasonably safe but is not entirely free of any side effects.
Risks for the mother
The majority of mothers given antenatal steroids tolerate it well. An extensive review of several trials in which antenatal steroids were administered to pregnant women, did not find any increased incidence of maternal death or chorioamnionitis (infection of the amniotic sac).
Transient elevation in glucose levels may occur in women starting 12 hours after the first dose of steroids and may last for several days. Diligent monitoring of glucose levels is essential, so an intervention can be instituted if needed.
It has been reported that white cell counts in the maternal blood tests tend to increase by 30% after steroid injections. Therefore, the diagnosis of infections may be more difficult in those cases.
Rare case reports of pulmonary edema have been described in women who received steroids while having chorioamnionitis and also receiving tocolysis (treatment to slow down uterine contractions). Pulmonary edema is a condition in which a patient retains too much fluid in the lungs, and that, in turn, leads to breathing problems. Sometimes it can be a very serious condition.
Potential risks of antenatal steroids for the baby
We know that the administration of steroids to babies after birth may be associated with a neurodevelopmental impairment such as cerebral palsy. At this time, we do not have useful data on long term neurodevelopmental outcomes of children who were exposed to steroids at more than 34 weeks of gestational age.
For premature babies exposed to antenatal steroids and born at less than 34 weeks, the general consensus is that steroids do not have a significant negative impact on their development.
Doctors monitoring babies in-utero after steroid administration need to be aware that steroids may affect fetal heart rate variability (decrease it) and also may increase blood flow in umbilical arteries during ultrasound studies.
Antenatal steroid treatment is a powerful tool allowing us to improve health outcomes in premature babies. Even though this treatment has been around for more than four decades, there is still a lot we need to learn regarding its positive and negative effects on women and babies.
If you would like to learn about the causes of premature birth, you may be interested in reading my article on this topic here.
This article is only for general information purposes. It should not be viewed as any medical advice. There is a chance that information here may be inaccurate. It would be best if you always discussed all health-related matters with your doctor before making any decisions that may affect your health or health of your family members.