The balance of the vaginal microbiota is delicate and easily disrupted by various factors throughout a woman’s life. Hormonal imbalances (menopause, premenstrual syndrome, pregnancy and the postnatal period, etc.) are a major cause. Taking antibiotics is another. And as is often the case, overall lifestyle has an impact on the balance of the vaginal flora.
Vulval hygiene and loss of moisture
Lifestyle and local hygiene in this area are key factors in a woman’s intimate comfort.
Hygiene : vaginal douching appears to have negative effects on the vaginal microbiota: indeed, repeated washing with water alone could cause long-term irritation to the mucous membrane. Using an unsuitable soap can alter the lipid balance of the vaginal mucosa, increasing water loss and heightening the risk of irritation. A very recent study (3) suggests that syndets – synthetic soaps often referred to as ‘soap-free soap’ – have a gentle cleansing effect, promote hydration of the area, maintain a pH suitable for the vulva and protect the vulval microbiota. They are therefore considered the most suitable for vulvar care.
Hormones: After the menopause and in the absence of hormone replacement therapy, the vulval epithelium becomes thinner and gradually atrophies. In postmenopausal women, the reduction in oestrogen levels leads, in particular, to greater epithelial fragility, as well as reduced hydration and increased susceptibility to irritation. (3)
Hydration and diet: Inadequate fluid intake or a lack of polyunsaturated fatty acids in the diet can have a negative impact on vaginal hydration.
Hormonal fluctuations and the vaginal microbiota
A woman’s life is a hormonal symphony. Hormonal fluctuations have a direct influence on vaginal health: hydration and the balance of the vaginal microbiota.
At puberty, levels of sex hormones gradually rise. This promotes thickening of the vaginal epithelium and the storage of glycogen. These are ideal conditions for the growth and proliferation of vaginal microorganisms. (4)
During menstruation, the pH of the blood (7.2–7.4) causes an increase in vaginal pH (which is normally acidic, around 4). This rise in pH leads to a significant increase in the risk of vaginal dysbiosis (imbalance) and, consequently, discomfort. Furthermore, during menstruation, iron from blood cells becomes a ‘food source’ for a number of bacteria (both beneficial and pathogenic). All of this leads to an increase in vaginal microbial diversity. It is therefore possible to experience intimate discomfort during your period. But nature works in wonderful ways: once your period has ended, sex hormones gradually begin to rise again and the epithelial cells of the vaginal wall thicken, releasing glycogen, which promotes the production of lactic acid, thereby lowering the vaginal pH and encouraging the proliferation of lactobacilli. Vaginal eubiosis (balance) is re-established. The discomfort then normally disappears naturally.
During pregnancy, the vaginal microbiota of the pregnant woman changes. At the very start of pregnancy, the immune system weakens to facilitate embryo implantation; the diversity of the vaginal flora then increases and the quantity of Lactobacillus decreases. As pregnancy progresses, the vaginal flora stabilises, once again making way for Lactobacillus lactis. These bacteria lower the pH of the vagina (which then becomes more acidic), thereby limiting the colonisation and growth of other bacteria, including harmful ones, and thus reducing the incidence of infections. (4)
During the menopause, the decline in ovarian function leads to a drastic reduction in oestrogen secretion, resulting in significant endocrine, physical and psychological changes. Physical symptoms include: dryness, irritation, pain and reduced lubrication (among others), all of which contribute to significant discomfort. (5) This can be partly explained by changes in the composition of the vaginal microbiota in postmenopausal women. One study showed that nearly 50 per cent of postmenopausal women had low levels of lactobacilli in their vaginal microbiome. Lower levels of lactobacilli are associated with a reduced libido and increased vaginal dryness (compared with women whose vaginal microbiota contains higher levels of lactobacilli). (4)
Antibiotic treatment
The main function of antibiotics is to destroy or prevent the growth of certain microorganisms. It is therefore easy to understand that antibiotics can disrupt the bacterial balance of the vaginal microbiota.