The vagina is naturally somewhat acidic with normal pH levels ranging between 3.5-4.5. A pH level of 0.1 is the most acidic, 7 is neutral and 14 is alkaline. So the natural environment of the vagina is somewhere between orange juice or carbonated drinks (please update table to carbonated drinks) and acid rain or tomatos!
Two common effects on pH
The hormone oestrogen promotes the growth of Lactobacilli, naturally occurring helpful bacteria, in the vagina. These bacteria in turn produce lactic acid making the vagina naturally mildly acidic. When the pH is normal that means that a healthy oestrogen level is present, normal lactobacilli are present, and other bacterial or trichomonas infections are usually not a problem. However, yeasts that cause infection can still live at this pH level and so thrush may still be an issue.
How this changes during pregnancy
During pregnancy there is an increase in oestrogen which makes more glycogen available. Glycogen is what lactobacilli need to thrive. Lactobacilli levels rise, producing more lactic acid which is believed to prevent the growth of unwanted disease-causing bacteria. In labour this may help to ensure that as the baby passes through the birth canal he is not exposed to many different kinds of harmful bacteria. The high level of lactobacilli does not necessarily lead to lowered pH levels during pregnancy as lactic acid has a pH of around 3.8. Yeast organisms also feed on glycogen, so the frequency of thrush during pregnancy may increase.
Maintain a healthy external pH Level!
To help limit the disruption of a natural pH level, think about your cleansing habits. Avoid cleansers with alkaline pH levels like harsh soaps.