Physiological vaginal discharge is made up of a combination of dead cells from the vagina, natural bacteria from the vaginal flora and mucus secretion produced by glands located in the walls of the vagina and vulva and next to the cervix. Normal discharge is generally between 1 and 4 ml in volume per day and its functions are to moisten and lubricate the vagina and to remove micro-organisms and dead cells.
Physiological vaginal discharge is stimulated by oestrogen and can therefore increase in volume during periods of increased hormonal stimulation, such as pregnancy. Another factor that increases the volume of discharge in pregnancy is the increased blood supply to the vaginal region.
This normal vaginal discharge is usually white, milky or clear, thick and with a slight odour, so a slight odour should not be a cause for concern as it is a common symptom of pregnancy. However, an unpleasant and intense odour may be indicative of a change in the vaginal microbiota due to infection.
Discharge that does not have the characteristics of physiological discharge should be evaluated by a doctor, as it may be a gynaecological infection. Signs of pathological discharge include: yellowish or greenish discharge; strong odour, pain, burning or dysuria.
Gynaecological infections during pregnancy are important because they are associated with numerous complications. Infections that cause vaginitis are the main causes of pathological discharge, including bacterial vaginosis, trichomonas, gonorrhoea, chlamydia and candidiasis. Bacterial vaginosis is caused by the overgrowth of anaerobic bacteria that normally inhabit the vagina. It is characterised by a fishy vaginal discharge and vaginal irritation.
