ObjectivePregnancy, a nutritionally demanding situation in terms of macro‐ and micronutrient supply owing to heightened maternal, placental, and fetal needs, significantly affects thiamine reserves. Thiamine deficiency during pregnancy and the postpartum period, presenting with varied manifestations and outcomes, is a relatively common condition in our population. The study aimed to understand the various manifestations and outcomes of acute thiamine deficiency in pregnant and postpartum women, emphasizing the significance of early recognition and thiamine therapy to prevent serious complications during pregnancy and after childbirth.MethodsThis prospective study conducted in a tertiary care center in North India enrolled consecutive pregnant and postpartum women presenting with clinical features consistent with thiamine deficiency disorders, such as thiamine deficiency‐related neuropathy, high‐output heart failure, heart failure with reduced ejection fraction, Wernicke's encephalopathy, gastric beriberi, and thiamine‐responsive acute pulmonary hypertension. In addition to capturing medical history including drug intake, dietary consumption, and comorbidities, women underwent brief relevant clinical examinations and laboratory assessments, including whole‐blood thiamine levels. Response to intravenous thiamine supplementation was also monitored.ResultsData of 31 women (12 pregnant, 19 postpartum) with a diagnosis of acute thiamine deficiency and a mean age of 28.88 ± 2.69 years were analyzed. The mean thiamine level was 1.28 ± 0.44 μg/dL with mean blood lactate of 3.46 ± 3.33. The most common presentation was gastric beriberi (n = 10), followed by paraparesis (n = 6), high‐output heart failure (n = 6), acute pulmonary hypertension, heart failure with reduced ejection fraction (n = 3 each), and an acute confusional state (n = 2). All patients responded to thiamine challenge.ConclusionIn the context of borderline thiamine status, particularly in our population with endemic thiamine deficiency and heightened demand for thiamine during pregnancy and the peripartum period, the deficiency can have varied and serious manifestations of dry and wet beriberi. Early recognition of the clinical features and thiamine therapy can be life‐saving. There is a need for validated clinical criteria owing to the non‐availability of thiamine testing in resource‐limited settings.