After how many weeks is fundal height no longer an accurate estimate of gestation?

Fundal height measurement is used to estimate gestational age and assess fetal growth by measuring the distance from the pubic symphysis to the top of the uterus (the fundus). This method is most accurate in the early to mid-pregnancy stages, typically up until around 20 to 30 weeks of gestation, when the uterus is still relatively mobile within the abdominal cavity.

After approximately 36 weeks, the fundal height tends to reach its maximum size, as the uterus becomes distended and pushing against the diaphragm. At this stage, variations in fetal position and other factors significantly influence fundal height measurements, making it an unreliable indicator of gestational age.

Thus, after 36 weeks, while fundal height measurements are still taken, they do not correlate consistently with weeks of gestation. Therefore, it is around this time that healthcare providers begin to turn to other methods, such as ultrasound, to more accurately assess fetal growth and gestational age.