Endocrine Abstracts

Background: Limited data support concerns that corticosteroid use in pregnancy, for maternal health reasons, can suppress the neonatal Hypothalamic-Pituitary-Adrenal (HPA) axis. We sought to determine if neonates born to mothers on high-dose steroids are at risk of adrenal suppression.

Methodology: Our tertiary neonatal unit guidance advises that babies born to mothers receiving ≥7.5 mg/day prednisolone for 28 consecutive days in the 3rd trimester undergo HPA-axis assessment. Prior to 2019, three cortisol samples taken eight hours apart on day three of life were advised (group-1). Since 2019, guidance recommends a standard-dose synacthen test (SST) after 24hours of age (group-2). Neonates who underwent HPA-axis assessment over seven years (July 2014-June 2021) were identified from laboratory records. Demographic data; maternal steroid formulation, dose and duration; and outcome of HPA-axis assessment were collated through retrospective case note review. We defined a normal SST as a peak cortisol >500nmol/l prior to April 2016 and >430nmol/l from April 2016, due to a change in assay. For group-1 normal cortisol was defined as two cortisol levels >100nmol/l or one >200nmol/l. Neonates not meeting this threshold required further investigation with SST.

Results: Over the study period, 56 neonates underwent HPA-axis assessment due to maternal steroid use in pregnancy. The steroid equivalent dose of prednisolone prescribed was 5 mg-40 mg, and duration ranged from one month to throughout the pregnancy. Thirty-four babies underwent an SST; (Group-1=16, group-2=18). All neonates requiring a SST in group-1 demonstrated a normal response. Three neonates in group-2 had a suboptimal response (peak cortisol 318-348nmol/l) and were managed with “sick day rule’ hydrocortisone. Mother-1 received 20 mg/day IV hydrocortisone for 3 weeks and 4 weeks of 5 mg/day prednisolone. Mother-2 received 20 mg/day prednisolone for 8 weeks. Steroid data were unavailable for mother-3. Baby-1 and 3 had a normal repeat SST after 6 weeks, baby-2 was lost to follow up.

Conclusions: The majority of babies born to mothers receiving corticosteroids during pregnancy do not have HPA-axis suppression. However, some neonates may be at risk of transient adrenal suppression. Further studies focusing on normal neonatal adrenal function and steroid use in pregnancy are needed to guide when HPA-axis assessment may be required.