Dietary guidance in Canada recommends a daily dietary source of vitamin D (from foods or a supplement) for ages 2 to 50 years old, including those who are pregnant. Additionally, it is recommended that those who could become pregnant and those who are pregnant or breastfeeding take a multivitamin containing folic acid every day. Most multivitamins in Canada contain vitamin D and thus provide a daily dietary source of vitamin D. The Canadian Health Measures Survey 2012-2019 shows that inadequate vitamin D status is prevalent in 18.3-29.6% of non-pregnant females of reproductive age (19-50 years). Canadian Community Health Survey 2015 Nutrition data on total usual intakes of vitamin D show that two thirds of participants who were pregnant or lactating at the time of the survey took a supplement containing vitamin D, but that the prevalence of inadequate intakes (i.e. below the Estimated Average Requirement of 400 IU per day) is 40.8% overall. Likewise, in the Maternal Infant Research on Environmental Chemicals cohort (2007-2011), the majority of participants report taking a multivitamin containing vitamin D during the first trimester, with the highest adherence rates observed in nulliparous females (>90%), and lowest rates of 74% adherence observed in multiparous (3+) females followed by declines in the second trimester to 64%. As such, multiparous females have lower vitamin D status during pregnancy a well as lower vitamin D content of breastmilk. The consequences of lower adherence to multivitamin use with multiparity are also observed in the offspring. For example, in a study that surveyed females upon delivery of a healthy term infant in Montreal (2016-2019), neonatal vitamin D deficiency is more prominent in multiparous pregnancies and with lower adherence to multivitamin supplementation. In addition, neonatal parathyroid hormone is elevated in association with vitamin D deficiency, Caesarean-section birth and being a female infant. Serum parathyroid hormone remained higher in a small subgroup born with vitamin D deficiency and subsequently assessed within 3 weeks postnatally, along with lower bone mineral density of the lumbar spine. These studies reinforce the importance of dietary guidance on multivitamin supplementation in pregnancy and that the benefits also extend to vitamin D status of both mother and newborn infant. Future research is needed to better understand multiparity and inequality in maternal and infant vitamin D status, and to identify strategies that may help to increase uptake of dietary guidance on multivitamin supplementation for a healthy - multiparous - pregnancy.