In some pregnancies, known as high-risk pregnancies, the mother and/or fetus are at an increased risk of experiencing complications. A pregnancy may be classified as high risk for a number of reasons, including:

• Age. Women over age 35 have an increased risk of certain chromosome abnormalities (e.g., Down syndrome) and placental problems (e.g., placenta previa). Studies also suggest an increased risk of miscarriage and low birth weight (less than 5 pounds, 8 ounces, or 2,500 grams) in pregnant women in this age group. There is also an increased chance of developing gestational diabetes and high blood pressure (preeclampsia). In addition, teen mothers are more likely to give birth prematurely than women over the age of 20 years.
  
  
• Multiple pregnancy. Women carrying two or more babies are at an increased risk for a number of complications, including premature labor and low birth weight. 
  
  
• Certain chronic health conditions. Many medical conditions can increase a woman’s risk of pregnancy complications. These may include:
  
  
• • Obesity
    
    
  • Diabetes mellitus
    
    
  • High blood pressure
    
    
  • Asthma
    
    
  • Kidney disease
    
    
  • Thyroid disorders (e.g., hyperthyroidism, hypothyroidism)
    
    
  • Parathyroid disorders (e.g., hyperparathyroidism, hypoparathyroidism)
    
    
  • Pituitary disorders (e.g., pituitary tumors, pituitary insufficiency)
    
    
  • Adrenal gland disorders (e.g., Cushing’s syndrome)
    
    
  • Blood disorders (e.g., blood clotting disorders, anemia, sickle cell anemia)
    
    
  • Autoimmune disorders (e.g., lupus, rheumatoid arthritis, scleroderma, myasthenia gravis)
    
    
  • Gastrointestinal disorders (e.g., Crohn’s disease)
    
    
  • Neurological disorders (e.g., epilepsy)
    
    
  • Phenylketonuria (PKU)
    
    
  • Group B strep infection
    
    
• History of gynecological problems. Women with a history of pelvic inflammatory disease (PID), endometriosis and certain other gynecological conditions are more likely to have complications, including ectopic pregnancy.

• History of cervical procedures. Women who have had certain cervical procedures (e.g., loop electrosurgical excision procedure [LEEP], cone biopsy) may have an increased risk for pregnancy complications. Women who have an incompetent or weak cervix or cervical stenosis may also result in labor problems.
  
  
• History of pregnancy loss. Women with a history of pregnancy loss (e.g., miscarriage, stillbirth, ectopic pregnancy) have an increased risk of developing complications with their pregnancies.
  
  
• History of premature birth. Women who have already delivered a premature baby are more likely to have pregnancy complications, including additional premature births.
  
  
• Sexually transmitted diseases (STDs). A number of STDs, such as HIV/AIDS, can be transmitted to a baby before, during or after birth, resulting in medical complications.
  
  
• Use of assisted reproductive technologies (ART). Women who become pregnant as the result of ART (e.g., in vitro fertilization) are at an increased risk of multiple pregnancy, a condition linked to numerous complications.
  
  
• History of abortion. Women with a history of two or more second-trimester abortions are more likely to have an incompetent cervix, a condition linked to numerous complications.
  
  
• Diethylstilbestrol (DES) exposure. Women who were exposed to DES when their mothers took the drug during pregnancy are at an increased risk for a number of complications, including ectopic pregnancy and preterm delivery.
  
  
• Use of an intrauterine device (IUD). Women who conceive while using an IUD as a form of contraception are more likely to experience a miscarriage. Women who become pregnant while using the progesterone-releasing type of IUD are also more likely to have an ectopic pregnancy.