As if the comments from strangers in the checkout line on the size of your belly weren't enough, your OB-GYN's measuring tape is now confirming what you felt to be true: Your baby bump is more of a boulder. And while you might be ready to snap at the next person who jokingly asks if you're sure you're not having twins, inside you might be wondering the very same thing. What does it mean if your stomach measures ahead during pregnancy? Should you be freaking out?
Probably not, says Certified Nurse Midwife Risa Klein. "It means one of several things: You are growing a perfectly sized baby, your baby is growing large, your amniotic fluid level may be high, or the ultrasound measurement may be off upwards of 15 percent."
The Manhattan Midwife is also careful to explain that while the fundal measurement in centimeters usually equals the woman's gestation in weeks, it is perfectly normal for the discrepancy to be off by two centimeters. That means that if a woman is 28 weeks pregnant, her fundal height is usually somewhere between 26 to 30 centimeters, not necessarily 28 on the dot.
Although it's possible that your care provider's measurement might be off, it's not likely: The method of measurement might look haphazard from where you lie, but its actually quite scientific. To determine what's called the fundal height, Klein tells Romper she measures the distance between the top of the pubis symphysis to the top of the uterus, which is called the fundus.
In the above example of a woman who is 28 weeks pregnant, Klein says she would only take additional precautions if the woman was measuring 32 centimeters or more, or the amniotic fluid level feels abundant. An ultrasound, Klein explains, "Can confirm if amniotic fluid levels are high, called polyhydrmanios, which can be a sign of late onset diabetes in pregnancy, or medical challenges with the baby’s ability to swallow amniotic fluid and lung absorption of fluid."
While that may sound like cause for concern, Klein says that it simply makes a case for early prenatal care. "Careful review of a woman’s nutrition and weight gain starting in the first trimester can reveal why her baby may be growing larger," she emphasizes. "And blood work drawn in the second trimester screens for gestational diabetes, which, if present, can contribute to a larger baby and more amniotic fluid."
Genetics also must be taken into consideration, says Klein, since it greatly affects the size and length of the baby. If both the mother and father are tall people, it's going to stand that their baby will more than likely be measuring longer than average.
Certified Nurse Midwife Linda Rice adds that some women simply carry their babies higher. "Women have differences in pelvic structure and muscle development, which is why different women look different pregnant. There is a lot of folklore about guessing the gender of a baby based on how a woman is 'carrying', but it has more to do with the woman herself," she tells Romper.
Rice also says that in her practice she has seen the fundal height be off in late pregnancy because the baby is not in the right position (meaning not head down). If a baby remains breech, it may tend to sit higher in the abdomen, while with a transverse baby, the measurement may be lower.
Of course, Rice notes, sometimes the baby simply had a growth spurt. "Just like newborns," she explains, "Fetuses don’t grow gradually and evenly, but have spurts and plateaus." So unless you have risk factors, such as diabetes or excessive weight gain, you likely have nothing to worry about by measuring large. Nothing, that is, except coming up with a quick comeback for the stranger in the checkout line.