No birth control method is completely effective, and the likelihood of pregnancy can depend on the type of contraception, whether it was fitted or prescribed correctly and how it was used. Becoming pregnant while using birth control does not automatically mean medical negligence has occurred.

However, you may be able to make a medical negligence claim if negligent advice, prescribing, treatment or follow-up caused an unintended pregnancy or another avoidable injury.

In this guide, our medical negligence experts outline different birth control options and when pregnancy or injury linked to contraception could support a claim.

What are the odds of getting pregnant on birth control?

The effectiveness of birth control varies between methods and depends partly on whether it is used correctly.

Long-acting methods such as an IUD, intrauterine system and birth control implant are more than 99 per cent effective. According to NHS statistics, the contraceptive pill is more than 99 per cent effective when used correctly all the time. With typical use, its effectiveness falls to 91 per cent, meaning around nine in every 100 women using the pill will become pregnant within a year.

The combined pill and progestogen-only pill, sometimes called the mini pill, must be taken according to the instructions. Vomiting, severe diarrhoea and some medicines can affect how oral contraceptives work.

Other common types of birth control include:

• Contraceptive injections, including Depo-Provera
• The vaginal ring
• Condoms
• Contraceptive patches
• Female and male sterilisation

The fact that a person became pregnant does not prove the method was prescribed, supplied or fitted negligently. The investigation must identify why the birth control failed.

When could pregnancy on birth control amount to medical negligence?

Incorrect fitting of an IUD or IUS

An intrauterine device must be placed correctly inside the uterus by a trained doctor or nurse.

A claim may be considered where:

• The IUD device was inserted incorrectly
• The device was not properly positioned
• Concerns about missing threads, pain or bleeding were not investigated
• A scan or examination should have been arranged
• The uterus was injured during fitting or removal
• The device caused organ perforation

Pregnancy with an IUD is rare, but it can happen even where the device was fitted correctly. A claim therefore depends on evidence that negligent medical care contributed to the pregnancy or injury.

Pregnancy while an IUD remains in place also requires prompt medical assessment because of the increased risk of ectopic pregnancy. An ectopic pregnancy develops outside the uterus, often in one of the fallopian tubes, and can cause severe pain and serious complications.

For more detailed guidance, readers can visit JMW’s article on whether they can make a compensation claim after becoming pregnant with an IUD.

Errors involving a birth control implant

The birth control implant is a small rod placed under the skin of the upper arm. It releases hormones that help prevent pregnancy.

Medical negligence may be relevant where:

• The implant was not inserted correctly
• A doctor failed to confirm it was properly implanted
• The implant was not replaced when required
• Relevant interactions with other medicines were overlooked
• Concerns about its position were not investigated

The medical records should show when and how the device was fitted, what advice was given and whether appropriate checks took place.

Incorrect advice about birth control pills

Birth control pills depend on correct and consistent use. The combined pill and progestogen-only pills work in different ways, including preventing ovulation and changing cervical mucus.

A doctor, nurse or pharmacist should provide clear information about:

• When to start taking birth control
• What to do after a missed or late pill
• Whether sickness or diarrhoea may reduce protection
• When another method of birth control is needed
• Which medicines may affect the pill
• Relevant birth control side effects

A claim may be investigated where incorrect prescribing or advice caused an unwanted pregnancy.

However, a claim will not usually succeed where correct advice was given but the pill was not taken as instructed.

Errors involving the contraceptive injection or vaginal ring

Contraceptive injections must be administered at the correct intervals. Protection may be reduced if an injection is delayed.

A claim may be possible where a healthcare provider:

• Recorded the wrong appointment date
• Administered the injection incorrectly
• Gave inaccurate advice about when it became effective
• Failed to explain when additional birth control was needed

Similar issues may arise where incorrect advice is given about inserting, replacing or using a vaginal ring.

Failed vasectomy

A vasectomy is a permanent birth control procedure, but it does not become effective immediately. Follow-up testing should confirm whether sperm remains present before other contraception is stopped.

Medical negligence may be relevant where:

• The wrong structure was cut
• The doctor performing the procedure did not seal the tubes correctly
• Follow-up testing was not arranged
• Test results were interpreted incorrectly
• The patient was advised too soon that the procedure had worked

The claim would need to establish that proper treatment or follow-up would probably have prevented the pregnancy.

Failed female sterilisation

Female sterilisation generally involves blocking or sealing the fallopian tubes to prevent pregnancy. If the procedure is carried out incorrectly, the wrong area is treated, or the patient receives inadequate advice about its effectiveness and any required follow-up, this may result in a wrongful conception and the potential for a failed female sterilisation claim.

To investigate what happened, solicitors will review the operation notes, consent records, follow-up appointments and any later scans or tests. Independent medical experts can then assess whether the procedure met a reasonable standard and whether the failure probably caused the pregnancy.

When would pregnancy not usually amount to medical negligence?

Pregnancy while using birth control does not itself show that a doctor or clinic is liable.

A claim may not be possible where:

• A recognised failure risk occurred despite appropriate care
• The birth control method was not used as instructed
• Pills were missed after clear advice had been provided
• An injection appointment was missed
• Another medicine reduced the effectiveness of birth control, but appropriate warnings had been given
• The patient stopped using other contraception before sterilisation was confirmed as effective
• Different care would not probably have prevented the pregnancy

Medical negligence law does not require birth control to work in every case. It requires doctors, nurses, pharmacists and clinics to provide care of a reasonable standard.

What happens if you become pregnant while taking birth control pills?

A person who receives a positive pregnancy test while taking birth control pills should contact a doctor, nurse or sexual health service for medical advice.

Taking the pill before realising you are pregnant does not automatically mean a miscarriage or injury will occur. A doctor can advise when to stop taking the birth control medication and whether any further assessment is required.

Symptoms such as severe pain, faintness, shoulder-tip pain or unusual bleeding require urgent assessment because they may indicate an ectopic pregnancy or another complication.

What about birth control side effects?

Not all contraception-related claims involve an unplanned pregnancy. A claim may also concern avoidable harm caused by prescribing or fitting errors.

Potential birth control side effects vary according to the method. Hormonal methods can carry a small risk of blood clots, and in rare cases a clot may cause a pulmonary embolism, stroke or heart attack.

An IUD can cause cramping or bleeding, particularly after fitting. If it is misplaced, it may cause significant pain or injury to the uterus.

The existence of a known side effect does not automatically mean negligent care occurred. A claim may be considered where:

• The birth control method was unsuitable because of the patient’s medical history
• Important risks were not explained
• Symptoms were not investigated appropriately
• The doctor failed to respond to warning signs
• Another, safer method should have been offered

What must be proven in a wrongful pregnancy claim?

Wrongful pregnancy claims arise where negligent contraceptive care results in an unintended pregnancy. Becoming pregnant while using contraception does not, by itself, prove that negligent care occurred, as no method is completely effective.

A claim normally requires evidence of two connected issues.

Breach of duty

It must be shown that the care fell below the reasonable standard expected from the doctor, nurse, pharmacist or clinic involved. This could include:

• Incorrectly fitting a contraceptive device
• Prescribing an unsuitable method
• Giving inaccurate advice about how or when to use contraception
• Failing to warn about relevant medicine interactions
• Not arranging appropriate checks or follow-up
• Performing a sterilisation procedure incorrectly

Causation

It must also be shown that the negligent care probably caused the pregnancy or additional avoidable harm.

For example, it may not be enough to establish that a birth control device was fitted poorly. Independent medical evidence may also need to show that, with correct fitting and appropriate follow-up, the pregnancy would probably have been prevented.

Similarly, where the issue involves incorrect advice about the contraceptive pill or a failed sterilisation procedure, the evidence must address what would probably have happened if reasonable care had been provided.

What evidence may support a claim?

Evidence may include:

• GP and sexual health clinic records
• Prescription and pharmacy records
• Birth control device fitting notes
• Consent forms
• Follow-up appointment records
• Pregnancy test results
• Ultrasound reports
• Sterilisation operation notes
• Records of advice about missed pills or medicine interactions
• Details of relevant symptoms and appointments
• Independent expert evidence

We begin by gathering the medical records and a detailed account of what happened. Independent experts may then assess whether the care met a reasonable standard and whether any failure caused the pregnancy or another injury.

What compensation may be available?

Compensation depends on the harm caused and the individual circumstances.

It may take account of:

• Physical injury caused by negligent fitting or treatment
• Pregnancy-related physical effects
• A recognised psychological injury
• Loss of earnings
• Medical expenses
• Travel costs
• Care needed during recovery
• Further treatment

Wrongful pregnancy is different from wrongful birth. A wrongful birth claim generally concerns negligent advice or diagnosis that deprived parents of the opportunity to make an informed decision about continuing a pregnancy where a serious medical condition was present.

Wrongful pregnancy claims concern a pregnancy that occurred following negligent contraception or sterilisation care.

Claims involving the costs associated with a child are legally complex. A solicitor must assess the particular facts and applicable law as generally the costs of raising a child cannot be claimed, unless they have a disability caused by medical negligence.

How long do you have to make a claim?

There is usually a three-year time limit for starting a medical negligence claim in the court process. In wrongful pregnancy claims, this will normally run from the date of the negligent treatment or the date you first knew, or could reasonably have known, that negligent care may have caused the pregnancy or other avoidable harm. This is known as the date of knowledge.

There are important exceptions to this time limit:

• People under the age of 18: the three-year time limit does not usually begin until their 18th birthday, meaning they generally have until their 21st birthday to start a claim. A parent or other suitable adult can bring a claim on the child's behalf before they turn 18.
• People who lack mental capacity: the three-year time limit may not begin while the person lacks the mental capacity to manage their own legal affairs. If they later regain capacity, the time limit will usually start from that date.

Although these exceptions exist, it is best to seek legal advice as soon as possible. This gives your solicitor time to gather medical records, obtain witness evidence and instruct independent medical experts while the evidence is still available.

Learn more about the time limits for making a medical negligence claim.