From the Guidelines
Betamethasone does not typically cause decreased fetal movement. Betamethasone is a corticosteroid commonly given to pregnant women between 24 and 34 weeks gestation when preterm delivery is anticipated, usually administered as two 12mg intramuscular injections 24 hours apart. The medication works by accelerating fetal lung maturity to reduce the risk of respiratory distress syndrome and other complications in premature infants. Some studies have observed a temporary reduction in fetal heart rate variability and fetal breathing movements for 48-72 hours after administration, but this is not the same as decreased gross fetal movement (kicks and turns that mothers can feel) 1.
Key Points to Consider
- The Society for Maternal-Fetal Medicine recommends offering a single course of antenatal corticosteroids to patients who meet specific inclusion criteria, such as those with a singleton pregnancy between 34 0/7 and 36 6/7 weeks of gestation who are at high risk of preterm birth within the next 7 days and before 37 weeks of gestation 1.
- The use of antenatal corticosteroids in select populations not included in the original Antenatal Late Preterm Steroids trial, such as patients with multiple gestations or fetal anomalies, may be considered on a case-by-case basis 1.
- It is essential to note that the long-term risks associated with antenatal corticosteroid use remain uncertain, and patients should be thoroughly counseled regarding the potential risks and benefits of antenatal corticosteroid administration 1.
Clinical Implications
- If a pregnant woman notices decreased fetal movement after receiving betamethasone, this should be reported to healthcare providers immediately as it may indicate a different underlying problem requiring evaluation, rather than being an expected effect of the medication itself.
- Clinicians should select candidates for late preterm corticosteroids who are likely to deliver preterm and avoid giving late preterm corticosteroids to patients outside the original ALPS inclusion criteria, including women with preexisting diabetes mellitus or women who have already received a course of corticosteroids 1.
From the Research
Effects of Betamethasone on Fetal Movement
- Betamethasone administration has been shown to cause a significant reduction in fetal movements, as observed in studies 2, 3, 4, 5.
- This reduction in fetal movement is transient, with movements returning to normal after treatment is discontinued 2, 5.
- The decrease in fetal movement is thought to be mediated by centrally located glucocorticoid receptors 2.
- Studies have also shown that betamethasone can cause a reduction in fetal heart rate variation and breathing movements 2, 3, 4.
Comparison with Dexamethasone
- Dexamethasone, another corticosteroid, does not appear to cause the same decrease in fetal movements as betamethasone 3, 4.
- However, both betamethasone and dexamethasone can cause a transient suppression of fetal heart rate characteristics and biophysical activities 4.
- The effect of betamethasone on fetal movement and heart rate variation is more pronounced than that of dexamethasone 4.
Clinical Implications
- The reduction in fetal movement caused by betamethasone can be misinterpreted as a sign of fetal distress, leading to unnecessary interventions 2, 6.
- Awareness of the transient effects of betamethasone on fetal movement and heart rate variation is important for clinical decision-making and can help prevent unwarranted iatrogenic delivery of preterm fetuses 2, 6, 4.