Hyperemesis gravidarum and vitamin K deficiency: a systematic review

Systematic review of case reports and one retrospective cohort study in pregnant women with hyperemesis gravidarum and vitamin K-related coagulopathy or deficiency, with some neonatal outcomes also described. The evidence base was small and largely observational, centered on women with severe vomiting, weight loss, and suspected or confirmed vitamin K deficiency.

Vitamin K supplementation was used to treat or prevent vitamin K deficiency in pregnancies complicated by hyperemesis gravidarum. In the reported maternal cases, vitamin K was given to 10 women, most often intravenously (60.0%); one neonate also received vitamin K, and one case included vitamin K as part of parenteral nutrition. Dose amount, frequency, and exact preparation were not consistently reported.

Vitamin K deficiency and related complications were reported in hyperemesis gravidarum, and supplementation was associated with normalization of prothrombin time in the reported cases. Among 21 women in the case reports, 8/21 (38.1%) had prolonged prothrombin time; in the cohort study, 10/39 (25.6%) had prolonged prothrombin time, and 2/10 had levels below 50%. Vitamin K was administered to 10/21 women and 1 neonate, with most maternal cases receiving intravenous vitamin K. Reported complications included maternal coagulopathy-related hemorrhage and neonatal intracranial haemorrhage or embryopathy, supporting the authors' conclusion that vitamin K deficiency may be clinically important in severe hyperemesis gravidarum.

The evidence is limited to case reports plus one retrospective cohort, so incidence and causality cannot be established. Vitamin K dosing, route, and timing were inconsistently reported, and the sample size was very small with substantial clinical heterogeneity. Neonatal and maternal outcomes were uncommon and may be subject to publication bias toward severe cases.