This research explores how bio-based materials might support everyday intimate care in non-medicalized ways. During the transition to motherhood, reproductive bodies undergo profound changes that disrupt bodily environments including the vaginal microbiome, skin barrier, and urinary tract. To surface these fluctuations, we explored pH-sensing materials from agar, carboxymethyl cellulose, and anthocyanin that indicate the pH of vaginal discharge, sweat, and urine via color change. Through co-creation with design researchers, we identified three dimensions for designing maternal care artefacts: ambiguity, visibility, and lenience. Combining material qualities, microbiology and feminist design approaches, we created three design provocations that integrate these materials into everyday care scenarios. Our work contributes to the social dimension of biodesign by nuancing bio-based material exploration for diverse human experiences and foregrounding bodily materials as integral to biodesign processes and outcomes, and further highlighting human–microbiome sensibilities, resisting medicalization of bodies, and materializing feminist critiques of self-tracking.