Guide to the Anonymised Register
Find out what the Anonymised Register is and how to get the most out of it.
We hold the longest running register of fertility treatment data in the world. World class research has been carried out using our data, either alone or by linking to other datasets.
We collect data and statistics about over 70,000 fertility treatments performed each year in the UK from 1991 to 2016. We are committed to making as much of this information available as possible to inform patients, researchers and clinicians.
Data we collect includes:
- identifying information such as name, date and place of birth of patients, their partner and any children born as a result of treatment
- reasons for seeking treatment and obstetric history
- the type of treatment being used, the number of eggs collected, and the number of embryos transferred
- the number of babies born, their gestation and birthweight.
Using register data for research
There are two main types of data which can be used:
- anonymised data, where no identifiers are present and some of the information is banded, or obscured, to protect patient privacy, and
- patient-identifying data, where the data may be very detailed, or contain actual identifiers (e.g., date and place of birth, names, address, place of treatment) allowing the records to be linked to another database.
Research can only take place within the strict confines of the law, which provides very strong protection of patient, donor and offspring confidentiality (stronger still than normal medical confidentiality).
Researchers who aim to use data in our Register only and not to link subjects to other datasets can use the anonymised version of the data in our Register. This anonymised dataset contains a large proportion of all the Register data going back to 1991, with the patient identifiers removed, and any secondary identifying fields aggregated or suppressed.
The anonymised Register allows professionals in the sector and the wider research community to make good use of the data we collect. The anonymised Register allows researchers to access a large and rich data set, but one that does not identify any patients, or children born as a result of treatment.
How useful is the anonymised register?
Research using anonymised data can still answer important questions, like which factors influence treatment outcomes, or which factors indicate that a patient should have only one or two embryos transferred during treatment. In fact, due to legislative changes in 2009, researchers can have greater coverage of treatment cycles using the anonymised dataset than one including patient identifying information.
Additional data fields
We're not currently able to produce bespoke versions of the anonymised data with further information added (for instance a maternal identifier, or more granular data) as this increases the risk of patient identification.
If you would like further information on how to gain access to more detailed data for research, please email intelligenceteam@hfea.gov.uk.
Helping us get more value from the anonymised Register
Although we are unable to provide detailed feedback or guidance on anonymised Register queries, we would like to hear about any projects using anonymised register data.
We will use this to provide better information for patients, the public and other researchers. This also helps inform our policy and future research.
Please email intelligenceteam@hfea.gov.uk to let us know of your progress.
Data quality and collection
We invested in our Information for Quality programme to transform the way we collect, use and publish information to benefit patients and other stakeholders. A large part of this involved developing a new data submission system and Register to improve the quality of the data we hold. This will be live from Autumn 2018.
The types of forms, the information that we have collected, and the method of data collection have changed over the years so some of the data that we hold is not present across all the years of the Register or to the same degree of quality.
Using the anonymised Register
Opening the data
The anonymised register is supplied as an excel file and split into multiple files due to the size.
The file has been designed to be easily imported into a range of applications used for analysis, but we cannot guarantee this functionality. Unfortunately, we are not able to provide guidance on how you can import the anonymised Register into any applications. Please see the application help guides provided by whichever software/application you are using for details on how to import this type of file.
Using the Data
The anonymised Register contains 87 fields of data on treatment cycles started between 1991 and 2016. We will aim to provide an updated every 15 months (i.e. by March 2018 for the 2016 year).
The content of each field is described in more detail in section 10.
Data Types
The anonymised Register includes 3 types of data:
- Number: Numeric Value
- Characters: Greater, Equal >=
- Binary Integer: True/false (1,0)
- Text: Alphanumeric data
Data fields
The anonymised Register contains 95 fields as detailed below.
Field |
Data type |
Description |
Patient Age at Treatment |
Text |
Patient’s age at treatment, banded as follows: 18-34,35-37,38-39,40-42,43-44,45-50 |
Date patient started trying to become pregnant OR date of last pregnancy |
Number |
The number of years ago that patient started trying to become pregnant or years since last pregnancy |
Total Number of Previous cycles, Both IVF and DI |
Number |
How many treatment cycles of IVF and DI the patient has previously had |
Total Number of Previous treatments, Both IVF and DI at clinic |
Number |
How many treatment cycles of IVF and DI the patient has previously had at the clinic associated with this treatment |
Total Number of Previous IVF cycles |
Number |
How many treatment cycles cycles of IVF the patient has previously had |
Total Number of Previous DI cycles |
Number |
How many treatment cycles of DI the patient has previously had |
Total number of previous pregnancies, Both and DI |
Number |
How many time the patient has previously been pregnant, Both and DI |
Total number of IVF pregnancies |
Number |
How many times the patient has been pregnant through IVF |
Total number of DI pregnancies |
Number |
How many times the patient has been pregnant through DI |
Total number of live births - conceived through IVF or DI |
Number |
How many live births the patient has had through IVF or DI |
Total number of live births - conceived through IVF |
Number |
How many live births the patient has had through IVF |
Total number of live births - conceived through DI |
Number |
How many live births the patient has had through DI |
Type Infertility Female Primary |
Bit |
1 if the main cause of infertility is due to the patient, 0 otherwise |
Type of Infertility – Female Secondary |
Bit |
1 if the secondary cause of infertility is due to the patient, 0 otherwise |
Type of Infertility – Male Primary |
Bit |
1 if the main cause of infertility is due to the partner, 0 otherwise |
Type Infertility – Male Secondary |
Bit |
1 if the secondary cause of infertility is due to the partner, 0 otherwise |
Type of Infertility – Couple Primary |
Bit |
1 if the main cause of infertility is due to the patient/partner problem, 0 otherwise |
Type of Infertility – Couple Secondary |
Bit |
1 if the secondary cause of infertility is due to the patient/partner problem, 0 otherwise |
Cause of Infertility – Tubal disease |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility - Ovulatory Disorder |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Male Factor |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Patient Unexplained |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility - Endometriosis |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Cervical factors |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Female Factors |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Partner Sperm Concentration |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Partner Sperm Concentration |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Partner Sperm Morphology |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility – Partner Sperm Motility |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Cause of Infertility - Partner Sperm Immunity |
Bit |
1 if the primary cause of infertility is as detailed, 0 otherwise |
Main Reason for Producing Embryos Storing Eggs |
Text |
A comma separated list of the main reason for this cycle which can include: Treatment Now, For Donation, For Storing Eggs, For Research |
Stimulation used |
Bit |
1 if this was a stimulated cycle, 0 otherwise |
Type of Ovulation Induction |
Text |
A comma separated list of the types of stimulation used |
Egg Donor Age at Registration |
Text |
If donor eggs were used, the donor's age at registration banded as follows: <=20,21-25,26-30,31-35 |
Sperm Donor Age at Registration |
Text |
If donor sperm was used, the donor's age at registration banded as follows: <=20,21-25,26-30,31-35,36-40,41-45,>45 |
Donated embryo |
Bit |
1 if this cycle used a donated embryo, 0 otherwise |
Patient acting as Surrogate |
Bit |
1 if the patient was acting as a surrogate in this cycle, 0 otherwise |
Type of treatment - IVF or DI |
Text |
IVF or DI |
Specific Treatment Type |
Text |
A comma separated list of specific treatment types used in this cycle |
PGD |
Bit |
1 if this cycle involved the use of preimplantation genetic diagnosis, 0 otherwise |
PGD treatment |
Bit |
1 if this cycle would be contained in the ‘PGD’ CaFC category on the HFEA website, 0 otherwise |
PGS |
Bit |
1 if this cycle involved the use of preimplantation genetic screening, 0 otherwise |
PGS treatment |
Bit |
1 if this cycle would be contained in the ‘PGS’ CaFC category on the HFEA website, 0 otherwise |
Elective Single Embryo Transfer |
Bit |
1 if this cycle involved the deliberate use of only one embryo, 0 otherwise |
Egg Source |
Text |
Indicates whether the eggs used in this cycle came from the Patient (P) or a Donor (D) |
Sperm From |
Text |
Indicates whether the sperm used in this cycle came from the Patient (P) or a Donor (D) |
Fresh Cycle |
Bit |
1 if this cycle used fresh embryos, 0 otherwise |
Frozen Cycle |
Bit |
1 if this cycle used frozen embryos, 0 otherwise |
Eggs Thawed |
Number |
If this cycle used frozen eggs, the number of eggs thawed |
Fresh Eggs Collected |
Number |
The number of eggs collected in this cycle |
Fresh Eggs Stored |
Number |
The number of eggs collected in this cycle and subsequently frozen |
Total Eggs Mixed |
Number |
The number of eggs mixed with sperm |
Eggs Mixed with Partner Sperm |
Number |
The number of eggs mixed with sperm from the partner |
Eggs Mixed with Donor sperm |
Number |
The number of eggs mixed with sperm from a donor |
Total Embryos Created |
Number |
The total number of embryos created in this cycle |
Eggs Micro-injected |
Number |
The number of eggs that were injected with sperm e.g. By ICSI |
Embryos from Eggs Micro-injected |
Number |
The number of embryos that were created in this cycle using ICSI |
Total Embryos Thawed |
Number |
If this was a frozen cycle, the total number of embryos that were thawed |
Embryos Transferred |
Number |
The number of embryos transferred into the patient in this cycle |
Embryos Transferred from Eggs Micro-injected |
Number |
The number of embryos transferred into the patient in this cycle that were created using ICSI |
Embryos stored for use by Patient |
Number |
The number of embryos that were created in this cycle and then frozen for subsequent use by the patient. |
Embryos (from Eggs Micro- injected) Stored for Use By Patient |
Number |
The number of embryos that were created in this cycle by injecting sperm and then frozen for subsequent use by the patient. |
Date of Egg Collection |
Number |
The number of days between egg collection and the first date provided in the series: egg collection date; egg thaw date; egg mix date; embryo thaw date; embryo transfer date |
Date of Egg Thawing |
Number |
The number of days between egg thawing and the first date provided in the series: egg collection date; egg thaw date; egg mix date; embryo thaw date; embryo transfer date |
Date of Egg Mixing |
Number |
The number of days between egg mixing and the first date provided in the series: egg collection date; egg thaw date; egg mix date; embryo thaw date; embryo transfer date |
Date of Embryo Thawing |
Number |
The number of days between embryo thawing and the first date provided in the series: egg collection date; egg thaw date; egg mix date; embryo thaw date; embryo transfer date |
Date of Embryo Transfer |
Number |
The number of days between embryo transfer and the first date provided in the series: egg collection date; egg thaw date; egg mix date; embryo thaw date; embryo transfer date |
Year of Treatment |
Number |
The year in which this cycle took place |
Live Birth Occurrence |
Bit |
1 if there were 1 or more live births as a result of this cycle, 0 otherwise |
Number of Live Births |
Number |
The number of live births as a result of this cycle |
Early Outcome |
Text |
A comma separated list of the results of a patient scan |
Number of Foetal Sacs with Foetal Pulsation |
Number |
If foetal sacs were present in the scan, the number of sacs that evidenced foetal pulsation |
1st Foetal Heart – Weeks Gestation |
Number |
The number of weeks of gestation for this foetal heart: banded for less that 30 weeks or greater than 40 weeks |
1st Foetal Heart – Birth Outcome |
Text |
Comma separated list of the outcome of this pregnancy: Embryo reduction; live birth; miscarriage; still birth; termination |
1st Foetal Heart - Birth Weight |
Text |
Banded birthweight of this child: Less than 1kg; Between 1.5kg and 1.99Kg; Between 1kg and 1.49Kg; Between 2.0kg and 2.49Kg; Between 2.5kg and 2.99Kg; Between 3.0kg and 3.49Kg; Between 3.5kg and 3.99Kg; Between 4.0kg and 4.49Kg; Between 4.5kg and 4.99Kg; Between 5.0kg and 5.49Kg; Between 5.5kg and 5.99Kg; 6kg or greater |
1st Foetal Heart – Sex |
Text |
The sex of the child: Male (M), Female (F) |
1st Foetal Heart – Delivery Date |
Number |
Year the child was delivered |
1st Foetal Heart – Birth Congenital Abnormalities |
Bit |
1 if a congenital abnormality was recorded, 0 otherwise |
2nd Foetal Heart – Weeks Gestation |
Number |
The number of weeks of gestation for this foetal heart: banded for less than 30 weeks or greater than 40 weeks |
2nd Foetal Heart – Birth Outcome |
Text |
Comma separated list of the outcome of this pregnancy: Embryo reduction; live birth; miscarriage; still birth; termination |
2nd Foetal Heart - Birth Weight |
Text |
Banded birthweight of this child: Less than 1kg; Between 1.5kg and 1.99Kg; Between 1kg and 1.49Kg; Between 2.0kg and 2.49Kg; Between 2.5kg and 2.99Kg; Between 3.0kg and 3.49Kg; Between 3.5kg and 3.99Kg; Between 4.0kg and 4.49Kg; Between 4.5kg and 4.99Kg; Between 5.0kg and 5.49Kg; Between 5.5kg and 5.99Kg; 6kg or greater |
2nd Foetal Heart – Sex |
Text |
The sex of the child: Male (M), Female (F) |
2nd Foetal Heart – Delivery Date |
Number |
Year the child was delivered |
2nd Foetal Heart – Birth Congenital Abnormalities |
Bit |
1 if a congenital abnormality was recorded, 0 otherwise |
3rd Foetal Heart – Weeks Gestation |
Number |
The number of weeks of gestation for this foetal heart: banded for less than 30 weeks or greater than 40 weeks |
3rd Foetal Heart – Birth Outcome |
Text |
Comma separated list of the outcome of this pregnancy: Embryo reduction; live birth; miscarriage; still birth; termination |
3rd Foetal Heart - Birth Weight |
Text |
Banded birthweight of this child: Less than 1kg; Between 1.5kg and 1.99Kg; Between 1kg and 1.49Kg; Between 2.0kg and 2.49Kg; Between 2.5kg and 2.99Kg; Between 3.0kg and 3.49Kg; Between 3.5kg and 3.99Kg; Between 4.0kg and 4.49Kg; Between 4.5kg and 4.99Kg; Between 5.0kg and 5.49Kg; Between 5.5kg and 5.99Kg; 6kg or greater |
3rd Foetal Heart – Sex |
Text |
The sex of the child: Male (M), Female (F) |
3rd Foetal Heart – Delivery Date |
Number |
Year the child was delivered |
3rd Foetal Heart – Birth Congenital Abnormalities |
Bit |
1 if a congenital abnormality was recorded, 0 otherwise |
4th Foetal Heart – Weeks gestation |
Number |
The number of weeks of gestation for this foetal heart: banded for less that 30 weeks or greater than 40 weeks |
4th Foetal Heart – Birth Outcome |
Text |
Comma separated list of the outcome of this pregnancy: Embryo reduction; live birth; miscarriage; still birth; termination |
4th Foetal Heart - Birth Weight |
Text |
Banded birthweight of this child: Less than 1kg; Between 1.5kg and 1.99Kg; Between 1kg and 1.49Kg; Between 2.0kg and 2.49Kg; Between 2.5kg and 2.99Kg; Between 3.0kg and 3.49Kg; Between 3.5kg and 3.99Kg; Between 4.0kg and 4.49Kg; Between 4.5kg and 4.99Kg; Between 5.0kg and 5.49Kg; Between 5.5kg and 5.99Kg; 6kg or greater |
4th Foetal Heart – Sex |
Text |
The sex of the child: Male (M), Female (F) |
4th Foetal Heart – Delivery Date |
Number |
Year the child was delivered |
4th Foetal Heart – Birth Congenital Abnormalities |
Bit |
1 if a congenital abnormality was recorded, 0 otherwise |
Review date: 3 January 2021