Preterm Birth Prevention Navigator

What actually prevents preterm birth — and what does not — matched to your pregnancy.

About 1 in 10 babies in the United States is born early — before 37 weeks. Most of the advice given about preventing early birth is either out of date or was never supported by good evidence in the first place. Bed rest is the classic example. It does not work.

This tool asks you a short set of questions and then shows you three things: where your risk sits, which treatments have real evidence behind them for a pregnancy like yours, and a checklist of what to ask your doctor or midwife. Every number here comes from a published study or guideline, listed on the references page.

Approximately half of preterm births follow spontaneous preterm labor, a quarter follow PPROM, and a quarter are medically indicated.¹ The evidence base shifted substantially after the April 2023 FDA withdrawal of 17-OHPC, the 2024 SMFM Consult Series #70, the SuPPoRT randomized comparison, and the 2025 updated IPD meta-analyses. This navigator implements those recommendations explicitly, including the points where ACOG and SMFM do not agree.

Input is client-side only. Nothing is transmitted or stored. Outputs are guideline-mapped recommendation sets with GRADE strength where the source assigns it, plus published absolute-risk anchors for the entered phenotype.

What this tool does

Risk profile — a structured risk tier plus published absolute risks that match your pregnancy
Cervical length & progesterone pathway — the actual decision algorithm, branch by branch
Prevention plan — a printable checklist of what to do, when, and what to ask
Evidence explorer — every intervention, its effect size, and its verdict

This is an educational tool, not medical advice. It cannot examine you, cannot see your ultrasound, and does not know your full history. It does not replace clinical judgment or your own clinician's assessment. If you are pregnant and having contractions, leaking fluid, bleeding, or pelvic pressure, contact your maternity unit now — do not use a web tool to decide.

Built on 22 source publications and guidelines — see the full Vancouver reference list.

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Your pregnancy

All questions on one page. Leave anything unknown as "not known" — the tool adapts.

This pregnancy

Current gestational age (weeks)

Whole weeks. Leave blank if pre-pregnancy planning.

How many babies?

Conception

Previous births

History of early birth

Earliest previous spontaneous preterm birth or second-trimester loss

Spontaneous means labour started on its own or the waters broke early — not an early delivery your team planned for a medical reason.

How many previous preterm births / late losses?

Time between last birth and this conception

Was a previous early birth medically indicated?

Cervix

Has your cervix been measured by transvaginal ultrasound this pregnancy?

Cervix open on examination before 24 weeks, without labour pains?

Previous cervical surgery

Known uterine anomaly (e.g. septate, bicornuate)

Treatment already in place this pregnancy

Other factors

Smoking or vaping nicotine

Conditions raising preeclampsia risk

These matter because preeclampsia is a leading cause of medically indicated early delivery.

Oily fish / omega-3 intake

Pre-pregnancy body weight category

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Your prevention plan

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Intervention evidence explorer

Every intervention studied for preterm birth prevention, with its effect size and verdict.

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Evidence base

Every number displayed in this tool traces to one of these publications. Vancouver format.

Verification note

All citations were checked against the source record (journal, year, volume, issue, pages, DOI) during the build. No reference, effect estimate, or confidence interval in this tool was generated from memory. Where an author list exceeds six names, the first six are given followed by et al. Where the full author list could not be confirmed, et al. follows the confirmed authors.

Guidelines change. ACOG Practice Bulletin 234 dates from 2021 and was updated in part by the 2023 Practice Advisory; SMFM Consult #70 dates from 2024. Confirm current status before relying on this tool clinically.