Big Fat Babies

Pregnant women with diabetes have to keep track of all sorts of numbers (carbs, ever changing insulin ratios, blood sugar results and A1c's) but perhaps the most vexing is the baby's weight. Any woman with diabetes (type 1, 2, or gestational) who has had a baby knows that diabetes contributes to macrosomia, also known as a baby that is large for gestational age (LGA). Fetal macrosomia has been defined in several different ways, including birth weight of 4000-4500 g (8 lb 13 oz to 9 lb 15 oz) or greater than 90% for gestational age after correcting for neonatal sex and ethnicity. Based on these definitions, macrosomia affects 1-10% of all pregnancies¹.

A large baby increases your chance of a premature birth, c-section, or difficult vaginal birth. Macrosomic babies are also at risk for shoulder dystocia, breathing difficulties and low blood sugar after birth.

Maternal diabetes is the most common cause of macrosomia. More precisely, maternal hyperglycemia means more sugar in the baby's blood as well. "Hyperglycemia in the fetus results in the stimulation of insulin, insulinlike growth factors, growth hormone, and other growth factors, which, in turn, stimulate fetal growth and deposition of fat and glycogen².

There are, of course, many other contributors to a baby's size (genetics, gestational age, baby's gender, and race), but those factors tend to get overlooked by both the doctor and the patient when a woman has diabetes.

When she has diabetes, a big fat baby is like a scarlet letter. Women who deliver average weight babies beam with pride over their accomplishment. Those who birth, oh, say a 10lb 10oz baby four weeks early... well, we spend a fair amount of time defending our diabetes self-management. To others, and to ourselves.

And women who walk out of their frequent ultrasound appointments with baby weight guesstimates that portend a big baby are often utterly terrified and filled with guilt. These amazing women, who are devoting every waking minute to trying to manage a disease that defies management (especially when hormones are wreaking havoc with their control) and who are committed to doing whatever it takes to have a healthy baby, these women are told or hear the message that high blood sugar equals large baby equals failure. And my heart breaks for them!

I went through two pregnancies where those other numbers (blood sugars) screamed "excellent control" but where the baby's weight (LGA from 18 weeks on) implied poor control. Which, in the eyes of your average ultrasound technician and L&D nurse, means mama didn't try hard enough.

I understand the need to put a consequence in front of people to motivate them to do their best. I just wish people would ease up on the guilt associated with diabetes numbers in general. To all you expectant moms with diabetes who are fretting over ultrasounds, please remember that estimated weight is just one piece of notoriously unreliable information, and don't beat yourself up over the prospect of a large baby! Because you have information and are being closely monitored, if your baby is large, your medical team will be prepared to deal with any potential problems. And to my sisters who delivered a big fat baby despite normal or near-normal A1cs, congratulations on the tremendous job you did bringing that new life into the world! He/she is beautiful :)