Autoimmune Disorders Pregnancy may increase the symptoms of, or change the course of, certain autoimmune disorders. Blood Pressure Problems High blood pressure during pregnancy comes in two forms—gestational hypertension and chronic hypertension, or hypertension that was present before pregnancy. Preterm Labor Preterm labor is labor that begins before 37 completed weeks of pregnancy. It includes contractions, and dilation of the cervix. Diabetes Changes that occur in your body while you're pregnant can cause your blood sugar to be too high. This is called gestational diabetes. Digestive and Liver Disorders In a few women, pregnancy can bring on severe nausea and vomiting, intense itching, or excess fat in the liver. Fetal Growth Problems Fetal growth problems include low birthweight and babies that are either too small or too large for their gestational age. Infections in Pregnancy Women may be more susceptible to the effects of infection during pregnancy because their immune system is naturally suppressed. Nervous System Disorders Disorders that are common in pregnancy include tension and migraine headaches. Pregnancy may also bring on more frequent seizures in women with epilepsy. Thyroid Disorders If you have a thyroid disorder, it's important to make sure your condition is under control while you are pregnant. Pregnancy Loss Most pregnancy losses are because of genetic or chromosomal abnormalities, but other factors can also play a role. Other Complications Certain medical conditions can become more severe during pregnancy: Heart disease and kidney disease are two examples.