Diabetes in Pregnancy
Diabetes is a disorder in which the levels of sugar in the blood are too high. This occurs because the body doesn’t produce enough insulin or can’t use insulin properly. Insulin is a hormone made by the pancreas that lets the body turn blood sugar into energy or store it as fat. In untreated diabetes, high blood sugar levels can damage organs, including blood vessels, nerves, eyes and kidneys. Some people with diabetes need daily insulin injections to prevent these complications.
About 1 in 200 women of childbearing age has diabetes before pregnancy (preexisting diabetes). Another 2 to 5 percent develop diabetes during pregnancy (gestational diabetes). Today, most of these women can look forward to having a healthy baby. While diabetes poses some risks in pregnancy, advances in care have greatly improved the outlook for these pregnancies.
What risks does diabetes pose to the baby?
Women with poorly controlled preexisting diabetes in the early weeks of pregnancy are three to four times more likely than nondiabetic women to have a baby with a serious birth defect, such as a heart defect or neural tube defect (NTD), a birth defect of the brain or spinal cord. They also are at increased risk of miscarriage and stillbirth.
Women with gestational diabetes, which generally develops later in pregnancy, usually do not have an increased risk of having a baby with a birth defect. However, some of these women may have had unrecognized diabetes that began prior to pregnancy. They may have had high blood sugar in the early weeks of pregnancy, which increases the risk of birth defects. Poorly controlled gestational diabetes also increases the risk of stillbirth. However, with improvements in medical care, stillbirth is rare.
Women with poorly controlled diabetes (gestational or preexisting) are at increased risk of having a very large baby (10 pounds or more). Macrosomia is the medical term for this. These babies grow so large because some of the extra sugar in the mother’s blood crosses the placenta and goes to the fetus. The fetus then produces extra insulin, which helps it process the sugar and store it as fat. The fat tends to accumulate around the shoulders and trunk, sometimes making these babies difficult to deliver vaginally and putting them at risk for injuries during delivery.
During the newborn period, babies of women with poorly controlled diabetes are at increased risk of breathing difficulties, low blood sugar levels and jaundice. These problems can be treated, but it’s better to prevent them by controlling blood sugar levels during pregnancy. Babies of women with poorly controlled diabetes also may be at increased risk of developing obesity and diabetes as young adults.
Why is pre-pregnancy care crucial for women with diabetes?
Women with preexisting diabetes should consult their doctors before pregnancy to ensure that their blood sugar levels are well controlled. This is important because the most serious birth defects associated with diabetes originate in the early weeks of pregnancy, before a woman may realize she is pregnant.
Studies have shown that blood sugar control begun before pregnancy largely eliminates the extra risk of birth defects for women with preexisting diabetes requiring insulin. Studies also show that excellent blood sugar control before and during pregnancy reduces the risk of miscarriage, stillbirth, macrosomia and complications in the newborn period.
When a woman with diabetes plans to conceive, doctors often recommend a blood test that measures glycosylated hemoglobin (a substance formed when glucose in the blood attaches to the hemoglobin protein in red blood cells) every one to two months. This test shows how well blood sugar has been controlled during the past two to three months. It can help determine when it is safest to try to conceive. The test also may be used to monitor blood sugar control during pregnancy.
All women should take a multivitamin containing 400 micrograms of the B vitamin folic acid, as part of a healthy diet, starting at least one month before pregnancy, to help prevent NTDs. Women with preexisting diabetes are at increased risk of having a baby with an NTD, so taking folic acid may be especially crucial for them. A recent study found that taking a daily multivitamin supplement before and during early pregnancy appeared to reduce the risk of birth defects in babies of women with preexisting diabetes. At a preconception visit, women with diabetes should ask their doctors whether they should take a daily dose of folic acid greater than 400 micrograms. While there are no studies on the use of larger doses of folic acid to prevent NTDs in women with preexisting diabetes, daily doses of 4,000 micrograms have proven successful in reducing the risk of having another baby with an NTD in women who already have had an affected baby.
Women with preexisting diabetes who take oral medications to control their blood sugar levels will probably need to switch to insulin before conceiving and during pregnancy because it is not known whether oral medications are safe during pregnancy, especially during the early weeks.
Other Articles of Interest
Prenatal Tests: First trimester tests Prenatal tests are one of the many ways your healthcare practitioner can check on your well-being and that of your growing baby. At
Preterm Birth: Most pregnancies last around 40 weeks. Babies born between 37 and 42 weeks of pregnancy are called full term. Babies born before 37 completed weeks
Pregnancy rates over the course of one year: Source: Management of the Infertile Woman by Helen A. Carcio and The Fertility Sourcebook by M. Sara Rosenthal Both of the above line graphs are for