Morning sickness in pregnancy: mini review of possible causes with proposal for monitoring by diagnostic methods

Abstract

Nausea, vomiting in pregnancy (NVP) and hyperemesis gravidarum (HG) can have adverse effects on the mother and foetus. High risk groups for HG seem to include young women, non-smokers, non-Caucasian and women carrying multiple foetuses. Medical databases show that oestrogen, human chorionic gonadotrophin (hCG), thyroxine and insulin are associated with NVP and HG by mechanisms that are unclear. It is possible that NVP and HG may have different hormonal aetiologies. Other risk factors implicated in NVP and HG include psychological and genetic as well as external factors such as smoking status, age, bacterial infection and diet. The hypothesis hereby proposed is that hypoglycaemia, nausea and vomiting are associated with pregnancy perhaps due to disturbances in metabolic control and increased requirements for glucose by growing foetus. During overnight fasting, the resultant hypoglycaemia possibly triggers nausea and vomiting. This calls for investigations and of note is whether severities of NVP and HG correlate to blood glucose levels. This proposal reviews current thinking on the causes of NVP and HG as well as possible pathology evidence-based monitoring measures.