It is very important that a reliable method of birth control is chosen as it is generally preferable that you do not become pregnant during periods of disease activity. The course of pregnancy usually parallels the state of the intestine, therefore if this is poor at the time of conception, the chance of relapse during pregnancy is higher.

The most popular method of birth control is the oral contraceptive pill, combining oestrogen and progesterone in varying doses.

There have been many studies carried out which suggest that the use of the oral contraceptive pill can predispose to the development of inflammatory bowel disease - particularly Crohn’s disease of the large intestine. These suggest that the risk is related to two main factors:
1. Duration of taking the pill.
2. Smoking.

It is well documented that smoking is an independent risk factor for the relapse of Crohn’s disease and the oral contraceptive pill is well known for its users being at increased risk of clotting in the blood vessels. These two factors could be responsible for diminished blood supply to the intestines resulting in the damage seen in Crohn's disease.

However, many thousands of women world-wide take the contraceptive pill without developing inflammatory bowel disease or any other complications, so evidence of the pill as a causal agent is very weak. It should also be noted that men suffer from inflammatory bowel disease also but do not take the oral contraceptive pill!

A very small percentage of patients with Crohn’s disease achieve complete remission on withdrawal of the contraceptive pill. However, it causes no harm in the majority of patients, but we would strongly recommend that if you take the oral contraceptive pill, you do not smoke.

The oral contraceptive pill is approximately 99% effective if taken correctly, however, inflammatory bowel disease, particularly Crohn’s disease, may greatly reduce its success:
1. The absorptive surface of the intestine may be poor due to inflammation and ulceration of the mucosa.
2. Increased transit through the intestine may make absorption unreliable.
3. Previous surgery may affect absorption if only a small amount of intestine remains.
4. Medications, such as antibiotics, may cause diarrhoea and/or vomiting and reduce the reliability of absorption.

You may need to take a higher dose pill than you usually take in order to increase the effectiveness.

We strongly advise that additional methods of contraception, i.e. the male (or female) condom, are used at times when absorption of the pill may be less than ideal, such as disease activity or whilst taking antibiotics.

It may be necessary to discuss alternative methods of contraception with your doctor or family planning clinic if conditions have altered, making continuing to take the pill an unreliable form of birth control.