Research standardization tools: pregnancy measures in the PhenX Toolkit

Am J Obstet Gynecol. 2017 Sep;217(3):249-262. doi: 10.1016/j.ajog.2017.05.058. Epub 2017 May 31.


Only through concerted and well-executed research endeavors can we gain the requisite knowledge to advance pregnancy care and have a positive impact on maternal and newborn health. Yet the heterogeneity inherent in individual studies limits our ability to compare and synthesize study results, thus impeding the capacity to draw meaningful conclusions that can be trusted to inform clinical care. The PhenX Toolkit (, supported since 2007 by the National Institutes of Health, is a web-based catalog of standardized protocols for measuring phenotypes and exposures relevant for clinical research. In 2016, a working group of pregnancy experts recommended 15 measures for the PhenX Toolkit that are highly relevant to pregnancy research. The working group followed the established PhenX consensus process to recommend protocols that are broadly validated, well established, nonproprietary, and have a relatively low burden for investigators and participants. The working group considered input from the pregnancy experts and the broader research community and included measures addressing the mode of conception, gestational age, fetal growth assessment, prenatal care, the mode of delivery, gestational diabetes, behavioral and mental health, and environmental exposure biomarkers. These pregnancy measures complement the existing measures for other established domains in the PhenX Toolkit, including reproductive health, anthropometrics, demographic characteristics, and alcohol, tobacco, and other substances. The preceding domains influence a woman's health during pregnancy. For each measure, the PhenX Toolkit includes data dictionaries and data collection worksheets that facilitate incorporation of the protocol into new or existing studies. The measures within the pregnancy domain offer a valuable resource to investigators and clinicians and are well poised to facilitate collaborative pregnancy research with the goal to improve patient care. To achieve this aim, investigators whose work includes the perinatal population are encouraged to utilize the PhenX Toolkit in the design and implementation of their studies, thus potentially reducing heterogeneity in data measures across studies. Such an effort will enhance the overall impact of individual studies, increasing the ability to draw more meaningful conclusions that can then be translated into clinical practice.

Keywords: PhenX; PhenX Toolkit; conception; cross-study analyses; data harmonization; delivery; depression; environmental exposure biomarkers; epidemiologic surveys; fetal growth assessment; gestational age; gestational diabetes; mental health; phenotypes; pregnancy; prenatal care; standard measures.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Databases, Factual / standards*
  • Female
  • Humans
  • Internet
  • Phenotype
  • Pregnancy
  • Research / standards
  • Research Design / standards*
  • Software*