Poster session I Clinical obstetrics, epidemiology, fetus, medical-surgical complications, neonatalogy, physiology/endocrinology, prematurity: Abstracts 87 - 236| Volume 208, ISSUE 1, SUPPLEMENT , S107-S108, January 01, 2013

235: A preconception nomogram to predict preterm birth


      Preterm birth is a leading cause of perinatal morbidity & mortality. Prevention strategies rarely focus on preconception care. We sought to create a preconception nomogram identifying women at highest risk for preterm birth using the Pregnancy Risk Assessment Monitoring System (PRAMS) surveillance data.

      Study Design

      PRAMS data from 2004-2009 was utilized. Odds ratios (OR) of preterm birth for each preconception variable were estimated and adjusted analyses were conducted. A validated nomogram predicting the probability of preterm birth was created using multivariate logistic regression model coefficients.


      192,208 cases met inclusion criteria. Demographic/maternal health characteristics and associations with preterm birth and ORs are reported (Table). After validation, significant predictors of preterm birth among all women, were prior history of preterm birth or low birthweight baby, prior SAB/TAB, maternal diabetes prior to conception, maternal race (e.g., NH black), intention to get pregnant prior to conception (i.e., did not want or wanted it sooner), and smoking prior to conception (p<0.05). Overall, our preconception preterm risk model correctly classified 76.1% of preterm cases with a negative predictive value (NPV) of 76.7%. A nomogram using a 0-100 scale illustrates our final preconception model for predicting preterm birth (Figure).
      Tabled 1Sample characteristics–Estimated preterm birth prevalences by subgroup
      Table thumbnail grr98
      Figure thumbnail grr97
      Summary nomogram for predicting the probability of preterm birth according to selected preconception risk factors using the PRAMS surveillance 2004-2009 data
      Instructions: using a pencil and ruler, draw a line vertically up to the top ‘Points’ axis to get an estimate of the points associated with each risk factor level for a given individual woman. Sum the points across all risk factors for that individual to create a ‘Total Points’ score. Draw a line vertically down from the ‘Total Points’ axis through the ‘Probability of preterm birth’ axis to obtain an approximation of the individual's baseline risk of preterm birth prior to conception.


      This preconception nomogram will give providers a tool to assist in predicting a woman's individual preterm birth risk and to triage high-risk women to preconception care. Future studies are needed to validate the nomogram in the clinical setting.