The mini-pill

(Date: March 2014. Version: 1.1)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by Public Health England on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

There are two types of oral contraceptive. 

The first, often called ‘the combined pill’ or ‘the pill’, contains synthetic versions of two hormones, oestrogen and progesterone, and includes brands such as: Alesse, BiNovum, Brevicon, Brevinor, Cilest, Demulen, Dianette, Evra, Femodene, Femodette, Gedarel, Katya, Levest, Levlite, Loestrin 20, Loestrin 30, Logynon,  Marvelon, Mercilon, Microgynon, Millinette, Mircette, Modicon, Necon, Norethin, Norimin, Norinyl-1, Ortho-Cyclen, Ortho-Novum, Ovcon-35, Ovcon-50, Ovral, Ovranette, Ovysmen, Qlaira, Rigevidon, Sunya, Synphase, Triadene, TriNovum, TriRegol, Yasmin, Zoely, and Zovia. 

The second type of oral contraceptive, known as the ‘progestogen-only pill’ or ‘the mini pill’ contains synthetic progesterone only, and includes brands such as: Cerazette, Femulen, Micronor, Norgeston, and Noriday.

Different brands of oral contraceptive may contain hormones in different forms and strengths.

There is quite a lot of information about babies whose mothers took oral contraceptives whilst pregnant. However, most studies have looked at oral contraceptives as a group rather than trying to examine the effects of each type of pill separately. The findings of these studies are summarised below.

Can taking oral contraceptives in pregnancy cause my baby to be born with birth defects?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

There is no scientific proof that taking oral contraceptives in early pregnancy causes birth defects.

Fifteen studies have all shown that women who have taken oral contraceptives during pregnancy are no more likely to have a baby with a birth defect than women in the general population.

Oral contraceptives contain sex hormones, and so some studies have specifically looked at whether taking oral contraceptives during pregnancy may affect the development of a baby’s genitals or internal sex organs (e.g. womb and ovaries). There is no scientific proof from these studies that women taking oral contraceptives during pregnancy are more likely to have a baby with abnormal sex organs, or to have a baby boy with hypospadias (where the urethral opening or hole is on the underside of the penis rather than at the tip).

Where other specific malformations have been studied:

• Most studies have not shown links between taking oral contraceptives during pregnancy and an increased risk of heart malformations.

• While some studies suggest that oral contraceptive use in pregnancy may increase the likelihood of having a baby with limb reduction defects (shortened or missing arms or legs), other studies have not shown this. When data from these different studies is put together and analysed, no link is seen.

• Studies have not shown links between taking oral contraceptives during pregnancy and neural tube defects (e.g. spina bifida) or trisomy defects (where the cells in a baby’s body contain an extra chromosome, as in Down’s Syndrome).

Taken together, the results of these studies do not show that taking oral contraceptives during early pregnancy causes any of these birth defects.

Can taking oral contraceptives in pregnancy cause miscarriage?

No increased risk of miscarriage was identified in three small studies of women who took oral contraceptives during pregnancy.

Can taking oral contraceptives in pregnancy cause preterm birth?

No studies have investigated preterm birth in women who took the oral contraceptive after conception. One study found that women who took oral contraceptives from one month before pregnancy up until the time of conception were more likely to give birth prematurely (before 37 weeks of pregnancy). More research is needed to establish whether there is a link between oral contraceptive use during pregnancy and preterm delivery.

Can taking oral contraceptives in pregnancy cause my baby to be small at birth (low birth weight)?

There is mixed evidence as to whether taking oral contraceptives during pregnancy increases the risk of having a low birth weight baby (<2500g). While two studies have shown that taking oral contraceptives during pregnancy may be linked to having a baby with a low birth weight, one study did not show such a link.  

Pregnancies in women taking the contraceptive pill are generally unplanned. It is therefore possible that women taking oral contraceptives may not be following the lifestyle advice recommended when trying to conceive. Not eating healthily, drinking alcohol and smoking in pregnancy are known to affect a baby‘s growth in the womb. These factors could explain why some studies found that babies of women taking the oral contaceptive in pregnancy were more likely to be small.

Can taking oral contraceptives in pregnancy cause stillbirth?

There is no known link between taking oral contraceptives in pregnancy and stillbirth, however no scientific studies have specifically investigated this. One study has shown that babies who were exposed to oral contraceptives in the womb are not at increased risk of dying around the time of birth or in infancy.

Can taking oral contraceptives in pregnancy cause learning or behavioural problems in the child?

A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.

There is no known link between taking oral contraceptives in pregnancy and learning or behavioural problems such as attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder (ASD) in the child. There are, however, no scientific studies that have specifically investigated a link with these problems.

Will my baby need extra monitoring?

As part of their routine antenatal care, most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and to check the baby’s growth.

There is no evidence to suggest that extra monitoring of your baby is required if you have taken oral contraceptives during pregnancy.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet please discuss them with your healthcare provider.  They can access more detailed medical and scientific information from  

General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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