Abstract

Background The Bristol IVF Study (BRIST-IVF) is a longitudinal clinical cohort, established to determine factors related to successful live birth and other outcomes following conception by assisted reproductive technologies (ART). This cohort profile describes recruitment, data collection and planned research.

Methods The study gathered comprehensive sociodemographic, lifestyle, anthropometric, and clinical data from women and their partners before and during treatment, as well as during pregnancy and after birth. Biological samples, including blood, urine, and saliva, were collected at initial recruitment and at pregnancy clinics, with cord blood and placental tissue obtained at birth. Participants consented to NHS record linkage, allowing access to pregnancy and birth outcomes from obstetric notes.

Results Between 3rd September 2019 and 30th June 2023, 502 couples or single women were recruited (967 individuals in total). Of these, 490 women underwent 1,055 ART treatment cycles during the study follow-up (up to 31st March 2024). Recruited women had a mean age of 35.8 years (SD = 4.4) and a mean BMI of 25.1 (SD = 4.4). At the time of recruitment, 251 women (50%) had never been pregnant, and 374 (75%) had not had a previous live birth. Women and their partners with a confirmed viable pregnancy at a scan performed at 7 weeks of gestation were invited to participate in the pregnancy follow-up study, with 305 women (for 324 pregnancies) invited. Data were collected from pregnancy questionnaires (n=246, 76%), pregnancy clinic data (n=119, 37%), and birth questionnaires (n=223, 69%). Collection of obstetric data from health records is ongoing.

Conclusion The BRIST-IVF cohort enables novel research into the predictors and consequences of ART conception, with comparison to a naturally conceived cohort, the second generation of the Avon Longitudinal Study of Parents and Children (ALSPAC-G2).

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This study was funded by the European Research Council under the European Unions Horizon 2020 research and innovation program (grant agreements No 101021566) and the NIHR Biomedical Research Centre at University Hospitals Bristol NHS Foundation Trust and the University of Bristol. The Wellcome Trust and UK Medical Research Council fund the ALSPAC G2 cohort and the clinic facilities that were used in participant follow-up (02215/2/13/2). A.T and D.A.L are supported by the UK Medical Research Council (MC_UU_00032/05). The views expressed in this publication are those of the author(s) and not necessarily those of any of the funders, the NHS, or the Department of Health and Social Care. None of the funders influenced the study design or analyses.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

All participants provided informed consent to participate in the study. Ethics approval for the study was obtained from the UK National Health Service South West- Frenchay Research Ethics Committee (IRAS project ID 236773, Initial approval 10/7/2019).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data Availability

We are keen to work with collaborators and welcome enquiries from researchers who are interested in the measures we have collected and have ideas for research questions beyond those listed above. In future, researchers will be able to apply to use anonymised subsets of the data for approved research questions.

List of AbbreviationsARTassisted reproductive technologyIVFin vitro fertilizationICSIintracytoplasmic sperm injectionBCRMBristol Centre for Reproductive MedicineEDTAEthylenediaminetetraacetic acidACDacid citrate dextroseBMIBody mass index