Context: Hyperemesis gravidarum (HG) is associated with an important morbidity and a high cost to society. The pathophysiology is not yet well known. Thyroid hormone and human chronic gonadotrophin play an important role in the occurrence of these vomitings.

 Objective: The aim of this study was to investigate whether HG was associated with biological hyperthyroidism and to try to clarify the links between biological hyperthyroidism and the severity of hyperemesis.

 Design: We reported a retrospective descriptive transversal study.

Methods: We gathered 138 patients who were hospitalized for HG during the first trimester of pregnancy over a period of 3 years (from January 1st 2014 to December 31st 2016) led within the department of obstetrics and gynecology “A” of the Charles Nicolle hospital in collaboration with the endocrinology unit of the department of internal medicine.

Results: The average age of our patients was 29, 6 ± 4,7 years. The average gestational age was 9,1 ± 1,6 weeks. The mean gravidity and parity were 1, 9 ± 1 and 0,5 ± 0,7. Ninety patients (65, 2 %) had biological hyperthyroidism. These patients were more likely to have fluid and electrolyte disturbances (74, 4% against 37,5 % for patients with euthyroidism). The same applies to liver function disturbances: 30% for hyperthyroid patients against 12,5% for euthyroid patients. Frequency of severe vomiting was significantly higher for hyperthyroid patients (74, 4% vs 41, 7%). The TSH was significantly lower and FT4 was significantly higher in patients with severe vomiting compared to patients with non–severe vomiting.

Conclusion: Biological hyperthyroidism is associated to hyperemesis gravidarum and its severity.