Women's reproductive health has attracted increasing attention in recent years, including in the field of microbiology. Vaginal infections, such as vulvovaginal candidiasis, bacterial vaginosis and aerobic vaginitis, are common and a huge burden on our society. The vaginal microbiome is important in the prevention of these infections, in fertility and for healthy pregnancies. The composition, and therefore the 'health' of the vaginal microbiome, is influenced by many internal and external factors, including intimate health. However, it is not yet known how intimate health, and specifically the use of menstrual hygiene products, affects the microbiome and women's intimate comfort and health. In this study, the researchers aim to understand the influence of 5 menstrual hygiene products (tampon, menstrual cup, menstrual pad and 2 types of menstrual underwear) on women's intimate health (n = 100). First, this will be evaluated at the microbiome level, focusing on the female intimate microbiome, consisting of the skin in the groin, vulvar and vaginal microbiome. These sites are all closely linked and are affected in vaginal infections or by contact with menstrual hygiene products. Second, in addition to the direct impact on the microbiome, the impact on the participant's immune system will be evaluated, as some well-known menstrual hygiene products can cause irritation and inflammation. As a third goal, participants will assess the comfort and usability of each menstrual hygiene product and provide data on their lifestyle and other factors that may influence our results. The main goal is to investigate and define the impact of menstrual hygiene products on women's intimate health so that women can make an informed choice. In a first phase participants (n = 1500) will fill in a survey containing questions on general health, lifestyle and menstrual health. Based on these responses a selection of 100 participants will be made by the researchers to participate in the intervention trial.