<P> Vaginal births are more common, but there are sometimes complications and a woman might undergo a caesarean section (commonly known as a C - section) instead of a vaginal delivery . The vaginal mucosa has an abnormal accumulation of fluid (edematous) and is thin, with few rugae, a little after birth . The mucosa thickens and rugae return in approximately three weeks once the ovaries regain usual function and estrogen flow is restored . The vaginal opening gapes and is relaxed, until it returns to its approximate pre-pregnant state by six to eight weeks in the period beginning immediately after the birth (the postpartum period); however, it will maintain a larger shape than it previously had . </P> <P> The vagina is a complex ecosystem that undergoes long - term changes throughout the life of a woman, from birth to menopause . The vaginal microbiota resides in and on the outermost layer of the vaginal epithelium . This microbiome consists of species and genera which typically do not cause symptoms or infections in women with normal immunity . The vaginal microbiome is dominated by Lactobacillus species . These species metabolize glycogen, breaking it down into sugar . Lactobacilli metabolize the sugar into glucose and lactic acid . Under the influence of hormones, such as estrogen, progesterone and follicle - stimulating hormone (FSH), the vaginal ecosystem undergoes cyclic or periodic changes . When the normal Lactobacillus - based microbiota changes to a microbiome populated by bacteria characteristic of Bacterial Vaginosis the risk of adverse pregnancy outcome is greater . </P> <P> The vagina is self - cleansing and therefore usually does not need special hygiene . Clinicians generally discourage the practice of douching for maintaining vulvovaginal health . Since a healthy vagina is colonized by a mutually symbiotic flora of microorganisms that protect its host from disease - causing microbes, any attempt to upset this balance may cause many undesirable outcomes, including abnormal discharge and yeast infection . </P> <P> The healthy vagina of a woman of child - bearing age is acidic, with a pH normally ranging between 3.8 and 4.5.; this is due to the degradation of glycogen to lactic acid by enzymes secreted by the Döderlein's bacillus, which is a normal commensal of the vagina . The acidity delays or slows the growth of many strains of pathogenic microbes . An increased pH of the vagina (with a commonly used cut - off of pH 4.5 or higher) can be caused by bacterial overgrowth, as occurs in bacterial vaginosis and trichomoniasis, or rupture of membranes in pregnancy . There are different types of bacterial vaginosis . </P>

What part of the internal female anatomy is self-cleaning