Crohn’s disease is a chronic inflammatory condition that primarily affects the digestive tract. For those planning a pregnancy, the key to a healthy outcome is maintaining disease remission throughout gestation. Crohn’s disease itself is not typically associated with causing structural birth defects. The primary concern is the potential for active inflammation to cause complications. Understanding the risks of active disease versus the risks of necessary medications is fundamental to managing a successful pregnancy.
Risk Associated with Active Disease
Uncontrolled inflammation from active Crohn’s disease poses a far greater risk to the developing fetus than most medications. When Crohn’s is active at conception or during pregnancy, the risk of adverse outcomes increases significantly. These outcomes are generally not structural malformations but relate to premature delivery and fetal growth restriction. Active disease increases the likelihood of miscarriage, preterm birth, and low birth weight.
Women who conceive while in remission for at least three to six months have pregnancy outcomes comparable to those without the disease. The ongoing inflammation creates a hostile environment that can compromise the placenta and limit nutrient delivery. Active Crohn’s disease can also lead to severe nutritional deficiencies that indirectly impact fetal development. Inflammation impairs the absorption of essential vitamins and minerals, such as folate and vitamin B12. Folic acid is especially important in the early stages of pregnancy to prevent neural tube defects, making deficiency a serious concern.
Medication Safety and Fetal Risk
Concerns about medications causing structural birth defects (teratogenicity) often lead women to consider stopping treatment, but this decision can be dangerous. Current medical consensus advises continuing most Crohn’s medications to prevent flares. The benefit of maintaining remission outweighs the minimal risks associated with most treatments. Only a few specific drugs are absolutely prohibited during the preconception and pregnancy periods.
Aminosalicylates and Corticosteroids
The class of drugs known as aminosalicylates (5-ASAs), including mesalamine and sulfasalazine, is considered low risk for use throughout pregnancy. These drugs are generally safe to continue. Women taking sulfasalazine require a higher dose of folic acid supplementation, typically two milligrams daily, to counteract the drug’s effect on folate absorption.
Corticosteroids, such as prednisone, should be used sparingly and only to treat a flare. Their use has been loosely associated with a slightly higher risk of low birth weight and gestational diabetes. However, corticosteroids are not strongly linked to an increase in congenital anomalies, and the risk of an active flare outweighs potential side effects.
Immunomodulators and Biologics
Immunomodulators like azathioprine and 6-mercaptopurine are widely used and can be continued throughout pregnancy. While these drugs are categorized as pregnancy category D, large prospective studies, such as the PIANO registry, have shown no increased rate of major congenital anomalies in infants exposed in utero.
Similarly, the anti-Tumor Necrosis Factor (anti-TNF) biologics, including infliximab and adalimumab, are generally considered safe and effective for maintaining remission during pregnancy. These medications are often continued, but the dose timing may be adjusted in the third trimester to limit the amount of the drug that crosses the placenta. This adjustment helps prevent temporary immunosuppression in the newborn.
The adjustment of anti-TNF agents in the third trimester is not done to prevent structural birth defects. It minimizes the infant’s exposure at birth, which can affect the timing of live vaccines after delivery. The anti-TNF agent certolizumab pegol is sometimes preferred because its unique structure results in much lower transfer across the placenta compared to other biologics.
Contraindicated Medications
Two specific drugs are strictly contraindicated due to their high teratogenic risk: methotrexate and thalidomide. Methotrexate, a folate antagonist, must be stopped at least three to six months before conception. Exposure during the first trimester can cause severe congenital malformations, known as methotrexate embryopathy.
Strategies for a Healthy Pregnancy
The most effective strategy for ensuring a healthy pregnancy is proactive planning and achieving deep remission before attempting conception. Women should work closely with a gastroenterologist and an obstetrician, preferably one specializing in high-risk pregnancies, to coordinate care. This multidisciplinary approach allows for the optimization of the treatment plan and nutritional status well in advance.
Achieving remission for three to six months prior to conception is the best predictor for a positive pregnancy outcome. This preparation period allows for necessary medication adjustments, such as switching from contraindicated drugs like methotrexate to safer alternatives. It is also the time to address nutrient deficiencies, including ensuring adequate intake of prenatal vitamins and high-dose folic acid, especially if taking sulfasalazine.
Ongoing monitoring is essential throughout the nine months, often including regular checks of inflammatory markers like fecal calprotectin. This helps detect subclinical disease activity. Patients must never discontinue maintenance medications without explicit medical guidance. Stopping treatment due to fear of medication risk is the most common reason for a flare, which dramatically increases the risk of adverse pregnancy complications. Medication adjustments should always be a planned decision made by the specialized care team.