Two-thirds of pregnancies in women with diabetes are unplanned. How long after conception do those women realize they’re pregnant? They may be eight weeks into their pregnancy before they know it’s happened.
If they’ve had high blood sugar during those eight weeks, the damage may already be done. Women with diabetes are three to five times more likely than non-diabetic women to have a baby with birth defects, and most of those malformations are caused by high blood sugar in the very first critical weeks when the fetal heart and brain are formed.
According to research by Dr. Mary Loeken, when a mother’s glucose levels are high, a protein called glucose transporter 2 (Glut2) is activated. It takes an excess of glucose to switch on Glut2, so in normal pregnancies Glut2 stays out of the picture. But in cases of poorly controlled blood sugar, Glut2 goes to work too early in the game and acts like a wide-open door, carrying those high levels of glucose to the embryo. The embryo is forced to soak it up like a sponge, two to three times faster than normal.
It takes a lot of oxygen for the embryo to break down all that glucose. At such an early stage, however, the embryo does not yet have its own heart or blood supply. Consequently, reports Dr. Loeken, oxygen is used up more rapidly than it can be delivered.
This creates what’s called hypoxic stress; in a sense, the fetus is suffocating. Hypoxic stress blocks the expression of a gene called Pax-3. The Pax-3 protein is necessary for formation of the spinal cord and heart because it keeps embryonic cells from dying. If Pax-3 is blocked, cells die and malformations are the result.
Dr. Loeken has also shown that high blood glucose levels increase an embryo’s production of free radicals. Embryos of oxygen-restricted mice showed the same large increases in free radicals as embryos exposed to too much glucose, suggesting that lack of oxygen caused by excess glucose triggers the production of free radicals that then contribute to birth defects.
The lesson of all this science is simple: If you have diabetes, you must protect your baby from high blood sugar, especially during its first few weeks. You cannot afford to let a pregnancy just happen when you are not in excellent control of your blood sugar. You must plan your pregnancy.
Keep in mind that over seventy percent of birth defects in babies of women with diabetes could be prevented by pre-conception care. If you take steps before pregnancy, your chance of having a healthy baby rises to that of the general population. Sweet Success, a California Diabetes and Pregnancy Program supported by the California Department of Health, reports that for women in their program who achieved a pre-pregnancy A1c of less than seven percent, the rate of anomalies was only 1.4 percent. Of women who enrolled in the program after their first trimester, however, eleven percent had babies with abnormalities.
The risk of congenital abnormalities among the babies of diabetic women is locked into a close correlation with blood sugar control at the time of conception. An A1c below seven percent carries no increased risk of abnormalities. With an A1c between 7.2 and 8.1 percent, the risk of abnormalities jumps to fourteen percent. For A1c’s between 8.2 and 11.1 percent, the risk is an appalling 23 percent, and over 11.2 percent, the risk rises to above 25 percent. That’s more than a one in four chance of a tragedy that could have been avoided.
Given such odds, you’d think that every diabetic woman who could possibly become pregnant would seek pre-conception care. Unfortunately, only three percent of women with diabetes enroll in a Sweet Success program before conception, and it’s likely that the numbers aren’t any better nationwide. Only one third of diabetic women who do not enroll in a Sweet Success program have an A1c of less than seven percent when they become pregnant. That leaves two-thirds at high risk of malformations.
These are discouraging statistics, and they’ve got to improve. You must work with your healthcare team to get your pre-pregnancy A1c below seven percent and to make all the other changes in your care that are critical for a healthy baby. Your doctor may put you on a four-milligram daily dose of folic acid before conception to reduce the risk of neural tube (spinal cord) defects. You may be told to convert from oral meds to insulin before you become pregnant.
If you are being treated with ACE inhibitors for high blood pressure, you must talk with your doctor about switching to a calcium channel blocker: ACE inhibitors can cause fetal kidney problems in the second and third trimester of pregnancy.
What if you don’t have diabetes? Well, are you sure about that? Millions of women have diabetes and don’t know it, and their babies are just at much at risk for birth defects caused by high blood sugar. So if you are obese, overweight, or have a family history of diabetes, see your doctor just to make sure.
If you’re in California, contact one of the two hundred state-wide providers of Sweet Success services. (For more information, see their website at http://www.llu.edu/llumc/sweetsuccess/.) It’s your responsibility to your baby.