Registering on PROSPERO means submitting your completed systematic review protocol to the international prospective register of reviews, where it is checked and given a public, timestamped record before you begin screening. Registration is free, is done through an online form, and signals that your methods were fixed in advance rather than shaped by the results.
Why a public timestamp protects your review
PROSPERO exists to stop two problems: duplicate reviews running unaware of each other, and authors quietly changing their methods once the results appear. By recording your plan publicly and dating it, registration makes outcome switching and selective reporting visible. That transparency is increasingly expected by journals, and a registration number is something reviewers look for. It is the natural next step once you have finished your systematic review protocol, and it is part of what separates a real review from a narrative literature review.
What PROSPERO accepts
PROSPERO registers protocols for systematic reviews of health and social-care topics that have at least one health-related outcome. It covers reviews of interventions, diagnosis, prognosis, and similar questions. It does not register scoping reviews or reviews already past the data-extraction stage. If your topic falls outside health, the usual home is OSF instead, a choice we lay out in PROSPERO versus OSF registration.
The registration process, step by step
1. Prepare the protocol first
The form mirrors a good protocol, so finish that first. You will need your framed question, your inclusion and exclusion criteria, your planned search strategy, and your intended risk of bias assessment ready before you start typing.
2. Complete the online form
Create an account, then work through the structured fields: title, anticipated dates, the review question, the databases, the eligibility criteria, and the planned synthesis. Save as you go. Most fields are mandatory, and vague answers are the main reason submissions bounce back.
3. Submit and wait for the check
After submission the PROSPERO team reviews your entry for completeness and eligibility before publishing it. This is an administrative check, not peer review, but it does take time, so build that wait into your timeline, as we note in how long a systematic review takes. Once accepted, you receive a registration number to cite. If the team returns the entry with queries, answer them precisely rather than padding; the check is testing whether your methods are specific enough to be reproduced, not whether the prose is polished.
What registration does not do
It is worth being clear about the limits, because a registration number is sometimes treated as a seal of quality it was never meant to be. Registration does not peer-review your methods, does not guarantee a journal will accept the review, and does not check whether your search strategy is actually comprehensive. What it does is create a public, dated record of intent, so that anyone reading the finished paper can see whether the primary outcome, the eligibility rules, and the planned analysis survived contact with the evidence unchanged. The value is entirely in that comparison: a registration nobody ever checks against the final review protects nothing, which is why the discipline of keeping the record current matters as much as creating it.
The fields that decide whether your entry is accepted
Submissions bounce back for the same handful of reasons, almost always because a field is vague where the register needs precision. The entries worth drafting carefully before you open the form are:
- Review title, which should name the population, intervention, and outcome rather than a topic alone, so the record is findable and unambiguous.
- Eligibility criteria, written tightly enough that two reviewers reach the same decisions, drawn straight from your PICO or related framework.
- Information sources, naming each database by name (MEDLINE, Embase, the Cochrane Library) rather than writing “standard databases”.
- Risk of bias method, where you commit to a design-matched tool such as RoB 2 for randomised trials before you know the results.
- Planned synthesis, stating whether you expect to pool the data and, if so, the effect measure and model.
A useful test is to draft each answer in your protocol document first and paste it in, rather than composing in the form itself. Because the PROSPERO form mirrors a complete systematic review protocol field for field, a finished protocol turns registration into a copy-and-paste exercise rather than a fresh round of decisions.
Common reasons a registration is delayed or returned
The administrative check is not peer review, but it does enforce completeness, and three problems account for most rejections. The first is a review already underway: PROSPERO will not register a review past the data-extraction stage, because the point is prospective timestamping, so submit before screening rather than after. The second is a thin search description that names no databases or omits the grey literature sources you intend to use. The third is an out-of-scope topic, most often a scoping review or a question with no health-related outcome, which belongs on OSF instead. Catching these before you submit saves a round-trip that can add a fortnight to the front of the project.
After registration: keeping the record honest
A registration is not frozen. As the review progresses you can, and sometimes must, update it, and PROSPERO keeps every version visible. The rule is the same as for the protocol itself: record every change with a date and a reason, which we cover in amending a protocol. An honest audit trail of changes is far stronger than a registration that pretends nothing ever moved. When the finished review is written up against the PRISMA 2020 guideline, the registration number is cited in the methods section, and any reviewer can then compare what you registered with what you reported. That public comparison is the entire point: it converts a private intention into a verifiable claim.