The question of whether steroids cause birth defects is complex because steroids are a large family of compounds with diverse biological actions. In medicine, this category includes two major groups: anabolic-androgenic steroids and corticosteroids, which function very differently within the body. The potential for harm depends on the specific compound, the dosage, the timing of exposure during gestation, and the reason for use. Any pregnant person currently using or considering a steroid medication must consult immediately with their healthcare provider.
Differentiating Steroid Types and Potential Harm
Anabolic-androgenic steroids (AAS) are steroid compounds structurally similar to the male sex hormone testosterone. These substances are primarily associated with illicit use for performance enhancement or bodybuilding and carry a high risk of severe birth defects if used during pregnancy. Exposure to these powerful androgens can cause significant teratogenic effects, particularly on a developing female fetus.
The primary risk from anabolic steroids is the masculinization of the female fetus, a condition known as virilization. This exposure can lead to the development of ambiguous external genitalia, where the clitoris is enlarged, and the labia may fuse, making the sex of the newborn difficult to determine at birth. These effects are directly linked to the potent hormonal activity of AAS, which overwhelms the fetus’s normal hormonal environment. The use of anabolic steroids during pregnancy is strongly discouraged due to the severe and often irreversible nature of these defects.
Corticosteroids When Treating Maternal Conditions
Corticosteroids, such as prednisone or hydrocortisone, are frequently prescribed to manage chronic maternal conditions like asthma, lupus, or autoimmune disorders. Maintaining maternal health is critical, as uncontrolled disease activity poses a greater risk to the fetus than the medication itself. These therapeutic steroids reduce inflammation and suppress the immune system, which can be life-preserving for the mother.
When systemic corticosteroids are required, the placenta acts as a protective barrier for many common types, such as prednisone and prednisolone. The placenta contains an enzyme that partially inactivates these compounds, limiting the amount of active drug that reaches the fetal circulation. Historical data suggested a very small increase in the risk of orofacial clefts, such as cleft lip, when used in the first trimester. However, recent studies have often failed to confirm this association or found the risk to be negligible.
The absolute risk of a cleft lip or palate from first-trimester corticosteroid exposure is very small, potentially increasing the background rate from 1.7 to approximately 2.7 per 1,000 live births. In contrast, local treatments, such as inhaled or topical corticosteroids, carry minimal risk. This is because very little medication is absorbed into the bloodstream, resulting in a negligible amount reaching the fetus.
Therapeutic Use for Fetal Lung Development
Corticosteroids have a specific, life-saving application: accelerating fetal lung maturation in cases of anticipated preterm birth. Antenatal corticosteroids, typically Betamethasone or Dexamethasone, are administered when there is a risk of delivery between 24 and 34 weeks of gestation. This brief, high-dose intervention significantly reduces the incidence and severity of neonatal respiratory distress syndrome, a leading cause of death and serious illness in premature infants.
The standard regimen involves a short course, such as two 12-milligram injections of Betamethasone administered 24 hours apart. These steroids are chosen because the placenta does not effectively inactivate them, allowing them to cross into the fetal circulation to act directly on the lungs. Treatment is most effective if delivery occurs between 24 hours and seven days after the first dose.
Concerns about long-term effects on neurodevelopment or growth have been studied extensively. The overwhelming consensus is that the benefit of preventing severe respiratory and neurological complications of prematurity outweighs the theoretical risks. While a single course of treatment can cause transient effects like reduced fetal breathing movements or temporary neonatal hypoglycemia, long-term follow-up studies have generally found no significant adverse effects on lung function or growth.
Guidelines for Safe Management During Pregnancy
Individuals who require steroid treatment during pregnancy should work closely with their entire medical team, including obstetricians and specialists, to create a management plan. A core principle of safe medication use in pregnancy is dose minimization, which involves using the lowest effective dose for the shortest necessary duration. Sudden cessation of prescribed corticosteroids is dangerous for the mother and can cause serious health complications, so it should never be done without medical guidance.
When long-term systemic treatment is necessary, the medical team will often choose a corticosteroid that is substantially inactivated by the placenta, such as prednisolone. For conditions managed with non-systemic treatments, healthcare providers will opt for inhaled or topical corticosteroids whenever possible to limit fetal exposure. Open communication with the medical team is essential to ensure that the mother’s health is maintained while minimizing any potential risk to the developing fetus.