Nutritional and immunological benefits of colostrum for neonatal growth and survival are well known. However, colostrum’s role as a conduit for bioactive factors that can affect neonatal development is not well understood. The lactocrine hypothesis for maternal programming of neonatal development was proposed as a mechanism whereby milk-borne agents, including the prototypical hormone relaxin (RLX), are delivered to nursing offspring to affect target tissues. Research goals were to understand how milk-borne agents, like RLX, affect neonatal porcine cervical development, by altering mediators of growth (estrogen receptor-alpha [ESR1], vascular endothelial growth factor [VEGFA] and the RLX receptor [RXFP1]), connective tissue remodeling (matrix metalloproteinase 2 [MMP2]) and apoptosis (anti-apoptotic BCL2 and pro-apoptotic cleaved caspase 3). Results showed biologically active proRLX in porcine milk during the first two weeks of lactation. Nursing for two days from birth was important for cervical ESR1, VEGFA and BCL2 protein expression, undetectable at postnatal day (PND) 0 and in replacer-fed gilts over the same period. Exogenous RLX failed to restore the cervical phenotype of replacer-fed animals to that of nursing gilts at PND 2. The extent to which this two day window of sensitivity influences subsequent cervical development at PND 14 was investigated. Cervical ESR1 and BCL2 proteins were detected in nursed gilts, but not in gilts fed replacer from birth through PND 14. VEGFA protein was detectable on PND 14 in both nursed and replacer-fed gilts, but was markedly reduced in PND 14 gilts fed replacer from birth. Active MMP2 was detected in both nursed and replacer-fed gilts by PND 14. Data support the lactocrine hypothesis, indicating that milk-borne factors are required to support protein expression patterns important for cervical development in the neonatal gilt. Results indicate that the first two days of life constitute a critical period for lactocrine signaling in porcine cervical tissues. Effects of disruption of lactocrine signaling on cervical development between birth and PND 2 persisted to PND 14 even when replacer-fed gilts returned to nursing after PND 2. If animals are colostrum-deprived, altered expression of morphoregulatory proteins could affect neonatal cervical development with long-term consequences for reproductive performance and health.