Height of fundus at comparable gestational dates: An assessment skill that's essential for all OB nurses and midwifes. The height of the fundus at comparable gestational dates varies greatly from patient to patient. Those shown are most common. Convenient rule of thumb is that at five months gestation, the fundus is usually at or slightly above umbilicus. Image source: Hytten F, Chamberlain G: Clinical Physiology in Obstetrics. Boston, Blackwell Scientific Publications, 1980.