Preterm Labor: Likelihood Ratios

Introduction: Generally defined as birth <37 weeks. See also tests to determine Risk of Preterm Labor. The patients here are symptomatic with labor.

[Edit Diagnosis] [Merge dx] [Add prevalence]

Tags: Obstetrical Tag this Diagnosis.

Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
women hospitalized for preterm labor between 18 and 34 completed weeks' gestation	13.4%	for delivery <35wk Am J Obstet Gynecol. 2006 Jan;194(1):138-43. PMID 16389023
Women with preterm labor	17.1%	for delivery within 28 days Acta Obstet Gynecol Scand. 2002 Jan;81(1):58-63. PMID 11942889
More, Edit...

The likelihood ratios of findings for Preterm Labor are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive and Negative Likelihood Ratios
Finding	Result	+LR	-LR
[ + ] Cervical Length Plus fFN	+ 0 -	8.6	0.2
cervical length <=20mm OR length 21-31mm + positive fFN for delivery within 28 days Study: Acta Obstet Gynecol Scand. 2002 Jan;81(1):58-63. PMID 11942889
[ + ] Cervical Length Plus fFN	+ 0 -	3.5	0.4
cervical length <=15mm OR cervical length 16-30mm + fFN >=50ng/ml for delivery <35wk in this study, results not significantly different from using fetal fibronectin alone (but saves fFN tests) Study: Am J Obstet Gynecol. 2006 Jan;194(1):138-43. PMID 16389023
[ + ] Cervical Length	+ 0 -	2	0.4
cervical length <=25mm for delivery <35 wk Study: Am J Obstet Gynecol. 2006 Jan;194(1):138-43. PMID 16389023
[ + ] Fetal Fibronectin	+ 0 -	3.3	0.5
>=50ng/ml, for delivery <35 wk Study: Am J Obstet Gynecol. 2006 Jan;194(1):138-43. PMID 16389023