Craniosynostosis (CS) is a condition characterized by premature fusion of one or more calvarial sutures. Numerous studies have demonstrated a correlation between CS and maternal hypothyroidism (MH), but research into this relationship has been scarce. A six-day-old male patient presented for initial neurosurgical consultation with trigonocephaly and prominent metopic ridging. A CT scan of the head confirmed the diagnosis of metopic CS, and it was revealed during the examination that the mother suffered from hypothyroidism during her pregnancy. Two theories provide a potential etiologic basis for the development of CS in infants born to hypothyroid mothers treated with levothyroxine. It is possible that the transplacental delivery of levothyroxine results in fetal thyrotoxicosis. Alternatively, intermittent periods of maternal hypothyroxinemia may encourage fetal thyroid hyperactivity to compensate for insufficient maternal thyroid hormones. Regardless, both theories must be formally investigated in order to elucidate the true association between CS and MH.