Fundal height, or McDonald's rule, is a measure of the size of the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

used to assess fetal growth and development during

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

. It is measured from the top of the mother's uterus to the top of the mother's pubic symphysis. Fundal height, when expressed in centimeters, roughly corresponds to gestational age in weeks between 16 and 36 weeks for a vertex fetus. When a tape measure is unavailable, finger widths are used to estimate centimeter (week) distances from a corresponding anatomical landmark. However, landmark distances from the pubic symphysis are highly variable depending on body type. In clinical practice, recording the actual fundal height measurement from the palpable top of the uterus to the superior edge of the pubic symphysis is standard practice beginning around 20 weeks gestation. Most caregivers will record their patient's fundal height on every prenatal visit. Measuring the fundal height can be an indicator of proper fetal growth and amniotic fluid development. Knowledge of gestational age may impact how the height is measured.

Fundal height landmarks

Shorter measure

A shorter measure can happen for one of the following reasons: *Fetus descent into the pelvis, seen normally two to four weeks before delivery *Error in estimated date of pregnancy based on first day of last menstrual period *Fetus is healthy but physically small * Oligohydramnios *Non longitudinal lie * Small for gestational age or Intrauterine Growth Restriction

Longer measure

On the other side, a longer measure can be caused by: *

Twins Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of Twin Last Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two e ...

, or other types of

multiple births A multiple birth is the culmination of a multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammals, with varying frequencies. Such births ...

*Error in estimated date of conception *Fetus is healthy but physically large * Gestational diabetes causing a larger baby * Polyhydramnios * Large for gestational age * Hydatidiform Mole *

Breech birth A breech birth is when a baby is born bottom first instead of Cephalic presentation, head first, as is normal. Around 3–5% of pregnant women at term (37–40 weeks pregnant) have a breech baby. Due to their higher than average rate of possible ...

As a

approaches its end, the fundal height will become less accurate. Symphysiofundal height is more accurate at 14–32 weeks.

References

{{DEFAULTSORT:Fundal height Obstetrics Midwifery