Fundal height is the measurement, in centimeters, from the top of your pubic bone to the top of the uterus on a pregnant woman. A doctor would expect your measurement to be 30 centimeters at 30 weeks, 32 centimeters at 32 weeks, and so on. Doctors generally consider it within the range of normal when a woman’s fundal height is 2 to 3 centimeters below or above her baby’s age in gestational weeks. Sometimes however, a woman can measure too small. This can be nothing at all, or it can be a red flag worth further investigating. Here are seven common reasons behind your small measurements:
1. Baby’s Position
Your fundal height may be measuring small if your baby is lying sideway in your womb in a transverse position. Though this is rare, it generally resolves before delivery. Your doctor may or may not try to rotate your baby’s position to turn him head down.
2. You’re Not as Far Along as You Thought
One reason you may be too small is perhaps you’re really five months pregnant, not six months. Perhaps you have the date of your last menstrual period miscalculated causing the doctors to think you are further along than you actually are.
3. Different Doctors
If you see multiple doctors or midwives for your appointments like I did, you may find that one doctor is more conservative than the next when it comes to measuring your belly. If you suspect this may be the reasoning behind your small measurements, request the same doctor measure you for each appointment.
4. You Carry Small
It seems that no two baby bellies look the same — every woman carries differently. Some women pop like a basketball while with others you can barely tell they are pregnant. If you have well-conditioned abdominal muscles then you may not “pop” as easily as others.
5. Your Baby Is Just Small but Healthy
Babies are born in all shapes and sizes. My fundal height measured 3-5 weeks small once I hit my 20th week in pregnancy up until birth. My daughter was born at 39 weeks and weighed a whopping 6.5 pounds and measured only 18.5″. She fit into preemie clothes for weeks and didn’t move out of newborn sized diapers till she was two months old. Now, at eight months old, she is still petite at only 15 pounds. There is nothing wrong with her; she is just a petite baby.
Also, you should consider your family history. Do small babies run in your family?
6. Low Amniotic Fluid
Low amniotic fluid levels, or oligohydramnios, is a pregnancy complication that can potentially cause serious harm to your baby and is usually first caught by small measurements followed by an ultrasound. Oligohydramnios can be due to complications such as birth defects, leaking membranes, and a baby not receiving enough nutrients leading to low urine production.
7. Intra-Uterine Growth Restriction
Intra-Uterine Growth Restriction , or IUGR, is a more serious condition that retards the growth of our baby. IUGR happens for a variety of reasons including chromosomal abnormalities, poor blood flow through the umbilical cord, or an infection. An expectant mother’s habits can also cause IUGR, including if she smokes, drinks alcohol, or does not eat properly. IUGR should only be diagnosed by your doctor and may require extra ultrasounds, including a Doppler ultrasound to determine the level of blood flow reaching the baby through the placenta.
Don’t be concerned just yet if your doctor finds your fundal height on the small side. You may find that it jumps up and down at each appointment, so your doctor usually waits for several consistent small measurements before referring you for a growth ultrasound. Chances are that you and your baby are just fine, but it is definitely worth further investigation to determine the cause of your small bump.
