Women who are pregnant with singletons are measured and monitored regularly, but for moms expecting multiples, finding out the average fundal height twins are expected to have is a bit more difficult to asses.
As long as a mom is gaining weight consistently and sufficiently, fundal height may not be a cause for any concern at all. But then, an understanding of fundal height twins has some significance.
What is Fundal Height and Why is it Useful to Know About it?
Fundal height is measured from the top of a mother’s pubic bone (symphysis pubis) to the highest point of the womb or uterus. This measurement is taken in centimeters and done usually at 20 weeks. The fundal height twins measurement usually follows the number of the weeks a mom is pregnant.
So, if for example, a mother is 25 weeks pregnant, it is usually expected to have a fundal height anywhere around 25 centimeters. Again, this measurement may be different in twin pregnancies.
According to the International Journal of Obstetrics and Gynaecology, finding out the fundal height in multiple pregnancies helps in predicting preterm labor as well as identifying SGA (small-for-gestational age) fetuses.
Note that fundal height is just a way to estimate fetal growth and offers merely reassurance of a baby’s steady growth.
Are There Different Ways of Measuring Fundal Height?
Yes, there are a number of techniques health care providers do to check the fundal height. The typical way is to use a tape measure to obtain the measurement.
Your healthcare provider will start measuring from the highest point of your uterus to the apex of the symphysis pubis (It is the place located below the belly button where the pubic bone starts). Then, he or she will record the fundal height measurement in centimeters. Aside from that, it is also possible to measure fundal height using the finger method.
Is There a Twin Fundal Height chart I Can Use for Reference?
Although it is difficult to asses the “average” fundal height for twin pregnancies, a primary basis would be that the fundal height measurement often matches the number of weeks a mom has been pregnant.
More specifically, after measuring the top of the pubic bone to the highest point of the womb or uterus in centimeters, the value should match the baby’s gestational age within one to three centimeters.
For example, if the measurement shows 22 centimeters, then the pregnant woman should be 19 to 25 weeks pregnant. The measurement thus increases as the pregnancy nears the due date. For more information regarding a standardized fundal height measurement, refer to this short video by the Perinatal Institute.
What Does it Mean if my Fundal Height Twins Measurement is Too Small or Too Large?
A fundal height that is smaller or larger than expected may be caused by many reasons. If the measurement is large for the gestational age, then this may mean any of the following:
- The due date is off (an ultrasound may be needed to find out a more accurate due date)
- The abdominal muscles are a lot looser compared to other women perhaps because of earlier pregnancies
- Being obese or having uterine fibroids
- Being pregnant with twins or more
- Excessive amniotic fluid
- The baby is in a breech or other unusual position
- The mom’s pelvis is narrow
- The baby has a condition known as macrosomia. or the baby is larger than the average. Macrosomia may indicate the presence of type 1 or type 2 diabetes before pregnancy or gestational diabetes
If, on the other hand, the measurement is considered small for the gestational age (more than 3 centimeters smaller than expected for the mom’s stage of pregnancy), then it may be because of having too little amniotic fluid or a condition known as intrauterine growth restriction.
Other reasons associated with a smaller measurement may be due to a mother having a more diminutive stature or well-conditioned abdominal muscles. This can also mean that the baby has dropped into the pelvis or that the baby is just tiny but perfectly healthy.
Fundal Height Twins: Always Consult Your Healthcare
Before jumping into conclusions about the fundal height twins should have, always be sure to consult your healthcare provider for any questions about your measurements and to have your pregnancy monitored closely.
Usually, an ultrasound will be recommended to determine the cause of unusual findings.