HLH is a rare but important differential to consider in the febrile pregnant or post-partum woman, conferring significant morbidity and mortality if not rapidly treated. Non-specific symptoms and clinical overlap with other syndromes, notably sepsis, make diagnosis challenging. The H-score is a useful tool for assessing probability of HLH based on biochemical, histological and clinical parameters, however, is not validated for use in pregnancy or puerperium. 

Bone marrow biopsy is considered diagnostic “gold standard” but negative biopsy does not exclude HLH.

There are no guidelines for management of HLH in pregnancy. In practice, immunosuppression remains the cornerstone of treatment. This is best done within a multidisciplinary team, alongside advice from a specialist HLH MDT. Immunosuppression should be viewed as the starting point of treatment. Diagnosis should prompt further investigations to identify underlying triggers, including a full immunological, histological and genetic work-up.