According to the literature review published in April 2022 by Walters et al (1) in the Cochrane Library, repeated doses of prenatal corticosteroids promote lung maturation in the baby and reduce serious health problems in the first weeks of life without harming health.

But according to MACS (2) and MACS-5 (3), only a single dose is recommended.

1. Walters A, McKinlayC, MiddletonP, HardingJE, CrowtherCA.Repeat doses of prenatal corticosteroids for women at risk of preterm birth for improving neonatal health outcomes. Cochrane Database of Systematic Reviews 2022, Issue 4. Art. No.: CD003935. DOI: 10.1002/14651858.CD003935.pub5.

2. Murphy KE, Hannah ME, Willan AR, Hewson SA, Ohlsson A, Kelly EN, Matthews SG, Saigal S, Asztalos E, Ross S, Delisle MF, Amankwah K, Guselle P, Gafni A, Lee SK, Armson BA; MACS Collaborative Group. Multiple courses of antenatal corticosteroids for preterm birth (MACS): a randomised controlled trial. Lancet. 2008 Dec 20;372(9656):2143-51. doi: 10.1016/S0140-6736(08)61929-7. PMID: 19101390.

3. Asztalos EV, Murphy KE, Willan AR, et al. Multiple Courses of Antenatal Corticosteroids for Preterm Birth Study: Outcomes in Children at 5 Years of Age (MACS-5). JAMA Pediatr. 2013;167(12):1102–1110. doi:10.1001/jamapediatrics.2013.2764