The Vaginal Microbiome Through Life: What Changes and Why

How does the vaginal microbiome change through life?

Oestrogen drives the whole pattern. It thickens the vaginal lining and increases the glycogen stored in it, and glycogen is the energy sourceLactobacillusbacteria depend on. When oestrogen is high, lactobacilli flourish, produce lactic acid, and keep the environment acidic. When oestrogen is low, they have less to feed on, and the community becomes more diverse and less acidic.

That single mechanism explains why the microbiome looks so different in childhood, in the reproductive years, and after menopause.

What happens at birth and in childhood?

Newborns are briefly influenced by their mother's oestrogen, which thickens the vaginal lining and leaves glycogen available, so lactobacilli can establish early on.

That effect fades within weeks. As maternal oestrogen is metabolised, the lining thins, glycogen drops, and lactobacilli decline with it. Through childhood the vaginal environment is neutral to slightly alkaline, with low Lactobacillus levels and a mixed community of anaerobic bacteria alongside aerobic species such as Staphylococcus and Streptococcus.

This is normal for that stage. A low-Lactobacillus community in a child is not the same finding as a low-Lactobacillus community in an adult.

What changes at puberty?

Rising oestrogen thickens the vaginal epithelium again and restores the glycogen supply, which selectively favours glucose-fermenting bacteria. Within a relatively short window the community begins to resemble an adult one, dominated by Lactobacillus crispatus, L. gasseri, L. iners or L. jensenii, depending on the person.

What happens during the reproductive years?

This is the stage where the microbiome is typically most Lactobacillus-dominant and most acidic, usually below pH 4.5. That acidity is one of the main reasons the environment is more resistant to other organisms establishing.

It still moves across the month. Oestrogen peaks in the follicular phase, and that correlates with the strongest lactobacilli dominance and the lowest bacterial diversity. During menstruation lactobacillidecreaseand organisms such asGardnerella vaginalisincrease, then the community typically recovers afterwards.

So a change you notice around your period is not necessarily a problem. It is the expected rhythm of the system.

Does the vaginal microbiome change in pregnancy?

Yes, and generally in the direction of greater stability. Lactobacilli tend to increase across pregnancy, diversity decreases, and bacteria associated with bacterial vaginosis become less dominant. L. crispatusis the most stable species across pregnancy. The size of this shift varies between individuals, and research has found it is most pronounced in women of African ancestry.

One thing worth knowing: bacterial vaginosis in pregnancy carries a small increased risk of complications, including miscarriage and premature birth. If you notice unusual discharge or an unusual smell while pregnant, speak to your GP rather than waiting to see whether it settles.

What happens after menopause?

Oestrogen falls, and the microbiome changes with it. The proportion of Lactobacillus drops considerably: research comparing pre-and perimenopausal women with postmenopausal women found abundance falling from around 83% to around 54%. Communities shift towards the more diverse, anaerobe-rich type, and vaginal pH rises.

Alongside this, many people experience vaginal dryness, burning, irritation or itching, discomfort during sex, and more frequent urinary tract infections or UTI-like symptoms. These are recognised symptoms of menopause and perimenopause, and they are treatable.

When should you see a doctor?

Speak to a GP, pharmacist or sexual health clinic if:

• Discharge changes in colour, smell or texture, or there is noticeably more of it
• You have itching, soreness, burning, or pain when you urinate
• You have pelvic pain, or bleeding between periods or after sex
• Symptoms keep returning or do not clear on their own
• You are pregnant and notice unusual discharge or odour
• You have any bleeding after menopause, which should always be checked
• Menopausal dryness or discomfort is affecting you, since there are effective treatments

Knowing what stage you are in helps you interpret a change. It does not replace a diagnosis.

How do you support your microbiome at each stage?

The general advice is the same throughout life, and most of it is about doing less. Avoid douching, perfumed soaps, vaginal deodorants, bubble bath and antiseptic liquids. Plain water and unperfumed soap are enough, and showers are gentler than baths. Not smoking helps.

What changes by stage is what to pay attention to. In the reproductive years, that is usually the pattern across your cycle. In pregnancy, it is reporting anything unusual promptly. After menopause, it is knowing that dryness and recurrent UTIs are treatable and worth raising with a GP.

If you want to see what your own community looks like at this point in your life rather than inferring it from symptoms, a test can show which bacteria are present and in what proportions.

→ How to Support a Healthy Vaginal Microbiome: The Complete Guide
→ What Is the Vaginal Microbiome, and Why Does It Matter?
→ 6 Signs of an Imbalanced Vaginal Microbiome (and What They Mean)
→ What Causes Vaginal Imbalance?
→ Health Checks Before Pregnancy