We conducted a survey of 535 New Zealand women to determine supplement use pre‐pregnancy, during pregnancy and while breastfeeding to evaluate adherence with national recommendations for folic acid and iodine supplementation. Our findings suggest that despite these women being well‐educated and motivated to complete an online survey, there was low adherence to recommendations for folic acid and iodine supplements. Only 38% of women reported supplement intake that met both folic acid and iodine recommendations. This cross‐sectional survey provides information useful to policy makers, clinicians and researchers seeking to protect and promote maternal and infant health.