What change occurs during puberty that helps protect the vagina from infections?

During puberty, the vagina undergoes significant hormonal changes influenced by the increase in estrogen production. One of the key changes is the alteration of vaginal pH to a more acidic environment. This acidic pH, typically around 4 to 5, helps to maintain the natural flora of the vagina, particularly the presence of Lactobacillus bacteria. These beneficial bacteria produce lactic acid, which further contributes to the acidic environment and acts as a barrier against pathogenic organisms.

By creating a more acidic pH, the vagina effectively reduces the likelihood of infections, as many harmful bacteria and pathogens do not thrive in acidic conditions. This adaptation is crucial for maintaining vaginal health and preventing issues such as bacterial vaginosis or yeast infections, which can occur when the natural balance of organisms is disrupted.

The other options, while relevant to vaginal health, do not directly describe the critical protective change resulting from puberty that enhances the vagina's ability to ward off infections. For example, physiologic leukorrhea refers to the normal white or clear discharge that occurs, which helps keep the vaginal area moist and maintain health, but it is the acidity of the vaginal pH that is primarily protective against infections.