I recently wrote about how we measure the uterus during pregnancy. The fundal height is the term for the distance from the pubic bone to the top or fundus of the uterus. So what does it mean if your fundal height is larger than expected?
First of all, only consider that you measure big if your doctor or midwife is concerned, or you feel a lot different than you did in a prior pregnancy. People in your life may feel the need to comment on your size and shape when you are pregnant, but this doesn't mean anything unless your practitioner is also concerned.
If you do measure big, several factors may be playing a role.
- Are you certain about the gestational age? A larger than expected uterus can be a sign that you are further along than expected. The earliest ultrasound is the most accurate for gestational age, so if you already had an ultrasound that confirmed a due date, wrong dates is an unlikely cause of measuring big.
- Are you carrying twins (or more)? Multiple pregnancy will make the uterus measure large, but ultrasound is very good at assessing the number of babies, so once you have had a good professional ultrasound that only saw one baby, you are very unlikely to be carrying twins.
- Everything may be fine. A large measurement is sometimes just a reflection on how you are carrying the baby.
- Are you overweight, with extra padding in front of the baby? If you are heavy the measurement may be several centimeters bigger than it otherwise would be, since the distance measured is affected by the thickness of the abdominal wall. Because we can't totally rely on our measurements in overweight women, we often get ultrasounds every month or so to check on the baby's growth.
- Is there extra amniotic fluid? The measurement of fundal height includes all the contents of your uterus, so if there is extra fluid, you may measure big. Extra fluid may be caused by maternal diabetes or by a problem that the baby has with swallowing, or it may be just a random, meaningless finding. If excess fluid is found, your doctor or midwife will tell you more about it.
- Is the baby extra big? Babies may grow large when the mother has uncontrolled diabetes, if she herself is overweight, if she has gained excessive weight during the pregnancy, or it can just be a random event. A larger baby means that a cesarean is more likely, although most babies, unless they are expected to be over ten or eleven pounds, can still deliver "from below." Keep in mind though that ultrasound is not as accurate as you might think for fetal weight; assessments are typically give or take 15%, which by the end of pregnancy may be more than a pound!
If the baby is found to be large, what should you do? If you are diabetic, be sure that your blood sugars are as normal as possible. If you are gaining weight at a rapid pace, see if you can slow it down by eating smaller portions and avoiding junk food. But you have to eat when you are hungry -- pregnancy is no time to go on a weight loss diet! Regular exercise may help slow your weight gain also.
Surprisingly, although you might think that inducing labor a few weeks before your due date would make for a better birth (since the baby wouldn't get even bigger), it turns out that induction itself can create problems, and increases the chance of needing a cesarean. Talk to your doctor or midwife to make a plan that is best for you and your baby.