Maternal and neonatal epidemiological features in clinical subtypes of preterm birth

Abstract

Objective: This study was designed to characterize and compare the maternal and newborn epidemiological characteristics through analysis of environmental factors, sociodemographic characteristics and clinical characteristics between the different clinical subtypes of preterm birth (PTB): Idiopathic (PTB-I), premature rupture of the membranes (PTB-PPROM) and medically indicated (PTB-M). The two subtypes PTB-I and PTB-PPROM grouped are called spontaneous preterm births (PTB-S).

Methods: A retrospective, observational study was conducted in 1.291 preterm nonmalformed singleton live-born children to nulliparous and multiparous mother’s in Tucumán-Argentina between 2005 and 2010. Over 50 maternal variables and 10 newborn variables were compared between the different clinical subtypes. The comparisons were done to identify heterogeneity between subtypes of preterm birth: (PTB-S) versus (PTB-M), and within spontaneous subtype: (PTB-I) versus (PTB-PPROM). In the same way, two conditional logistic multivariate regressions were used to compare the odds ratio (OR) between PTB-S and PTB-M, as well as PTB-I and PTB-PPROM. We matched for maternal age when comparing maternal variables and gestational age when comparing infant variables.

Results: The PTB-I subtype was characterized by younger mothers of lower socio-economic status, PTB-PPROM was characterized by environmental factors resulting from inflammatory processes, and PTB-M was characterized by increased maternal or fetal risk pregnancies.

Conclusions: The main risk factor for PTB-I and PTB-M was having had a prior preterm delivery; however, previous spontaneous abortion was not a risk factor, suggesting a reproductive selection mechanism.

• Clinical subtypes
• epidemiological features
• pregnancy
• preterm birth

Acknowledgements

The authors would like to thank the support and hard work of the health care team at Maternidad Nuestra Señora de la Merced, in Tucumán, Argentina. Also, Gladys Mirta Leguizamón; Mercedes Elizabeth López; Marta Inés Gonzales de Padilla, and all the preterm infants’ families. Nancy Weathers at the University of Iowa provided database and informatic support.

Declaration of interest

This work was supported by the March of Dimes grant #6-FY08–260 and NIH grant 1R01 HD-52953 and by the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT), Argentina. Grant Number: PICT 2008-0429.