In mid- to late-term pregnancies, the width of the posterior cranial fossa pool is usually <1 cm, and >1 cm should be followed up closely and antenatal examinations should be performed if necessary. If the width of the posterior cranial fossa pool is not very obvious, and if it is maintained from 24 to 38 weeks, it is not necessary to worry too much, and follow-up should be done. If the posterior cranial fossa pool is 1 cm wide, it is considered to be a critical value for hydrocephalus and is not indicative of a problem. It is safe to consider regular review as long as it does not continue to rise. Pregnant women should drink more water, pay attention to rest, observe the condition of amniotic fluid, and actively review for absorption.