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Crohn’s Disease: Issues for Pregnancy

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Crohn’s disease is one of the main types of inflammatory bowel disease, a family of conditions that are long-term and relapsing. Inflammatory bowel disease strikes about 31 per 10,000 pregnant women, according to an Australian study published in 2016. The prevalence of such disease probably varies throughout the world, but the Australian study implies that Crohn’s disease is fairly common during pregnancy. The following groups of people are at highest risk of having Crohn’s disease:

  • Those with a first degree relative (parent, sibling, or child) with an inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis.
  • Ashkenazi Jews
  • Smokers
  • Those who use non-steroidal anti-inflammatory drugs (NSAIDs) on a long-term basis

The first two of the above risk factors indicated that the condition has a strong genetic component. Such a condition is said to be heritable. The second two factors suggest that one’s risk is modifiable based on the environment and behavior. Crohn’s disease often affects women and often begins at a young age, with an onset typically between ages 15-30, so it can coexist with pregnancy, in which case the pregnancy is considered complicated.

Crohn’s disease can affect any part of the gastrointestinal tract, from mouth to anus, but usually it strikes the terminal ileum (the last part of the small intestine) and colon, and typically leaves the rectum intact. The main symptoms, which may come and go, include diarrhea (sometimes with blood), nausea, and vomiting. Often the diarrhea comes at night and there is often melena (black stool, resulting from blood mixing into the feces). Other symptoms include anorexia (you are severely under weight), fevers, and abdominal pain, typically in the central or right part of the lower abdomen. The pain can be dull or crampy and its severity varies.

Diagnosis begins with a suspicion for Crohn’s disease based on the patient’s history. This includes having family members with inflammatory bowel disease and being an Ashkenazi Jew. There may also be a history of bone fractures, which could give the doctor another clue. Usually, there is a gradual onset of the following symptoms, which get worse as time goes on. On physical examination, the doctor may find the liver and spleen to be enlarged. Once Crohn’s disease is thought to be a possibility, various tests will be conducted on blood samples for signs of anemia, vitamin deficiencies, parasitic infections, iron deficiency, and evidence that the immune system is attacking the body. Doctors will also order what’s called a complete metabolic panel that reveals various aspects of your blood chemistry and your kidney function. Samples of stool will be taken to look for bacterial and parasitic infections, blood, and signs of inflammation. Various genetic tests will be performed to determine whether you carry any genetic sequences that are particularly associated with Crohn’s disease. Finally imaging studies will be conducted. These will include either computed tomography (CT) enterography, or a similar test called magnetic resonance (MR) enterography. Your may also be given either an MRI of your abdomen, or a CT scan of your abdomen. If you are already pregnant, the MRI will almost always be chosen over an abdominal CT.

Most importantly, the inside of your colon and part of your small intestine will be examined with colonoscopy, in which a tube-like instrument is inserted through the anus. This will provide your doctors with video footage of the inner lining of the parts of the gastrointestinal tract that are scanned, plus they will be able to take biopsies of selected areas. If you are suspected of having Crohn’s disease that involves higher parts of the gastrointestinal tract, such as the stomach and esophagus or the part of the small intestine that’s near the stomach, you also will be tested with an instrument that enters through the mouth in order to view areas that colonoscopy cannot reach. Another test called capsule endoscopy, you swallow a wireless camera that is enclosed in a pill-sized capsule, which progresses through the gastrointestinal tract collecting and sending data to a recording belt on your waist. Eventually, you excrete the capsule.

Crohn’s disease will put you at risk for nutritional deficiencies and gastrointestinal tract bleeding that can be exacerbated by pregnancy. It also will make it more likely that you will have to give birth by caesarean section. If your disease becomes very severe during pregnancy such that you require surgery on your colon it is possible that the surgery can trigger premature labor. Various complications can develop, such as an abscess (a collection of pus), perforations in the gastrointestinal tract, connections between parts of the intestines and between parts the intestines and other organs, and nutritional deficiencies due to problems absorbing nutrients from food. Your colon also can produce toxins in severe cases. Loss of nutrients and blood through the gastrointestinal tract can lead reduced fetal growth. If folic acid intake is inadequate, this can also put your child at risk for neural tube defects, in which parts of the brain or spinal cord are left without a bony covering. IBD puts your embryo/fetus at risk for various poor outcomes, such as low birth weight, congenital abnormalities, and even stillbirth.

Several medications are given to control Crohn’s disease. Most of the drugs are thought to be safe during pregnancy, while others have raised concern. In particular, anti-tumor drugs, which are given in Crohn’s disease to oppose the inflammatory process, are potentially dangerous during pregnancy. One common example is the drug methotrexate. It is absolutely contraindicated in pregnancy. 5-aminosalicylic acid (5-ASA, mesalamine) is common treatment and appears to be fairly safe, both in pregnancy with the exception of one brand, called Asacol HD, although the preparation is being adjusted to make it safe.

Various antibiotics can be given to control gastrointestinal infections without harm to the fetus. Metronidazole and amoxicillin-clavulanic acid both are considered to be low risk. Another class of drugs is steroids, the safety of which is a subject of debate, but since they are very effective they are always on the list of medications that can be given during pregnancy if needed. If given for long periods, however, steroids may provoke gestational diabetes and also raise your blood pressure, but these are things that can be monitored. There is some concern about various drugs known as biological agents (specially-designed antibodies), but studies have been very limited. Two other commonly used drugs are called azathioprine and 6-mercaptopurine. Both are considered acceptable in pregnancy, if other treatments prove ineffective or for some other reason cannot be used. In addition to medications, smoking cessation programs may possibly reduce the amount and severity of Crohn’s disease flareups. Regular exercise also may be helpful. Various surgical treatments also may become necessary in cases when particular parts of the gastrointestinal tract are affected severely. Such operations normally are not scheduled during pregnancy.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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