ACOG Practice Bulletin: Antepartum Fetal Surveillance July 2014, Number 145.
ACOG Practice Bulletin: Prediction and Prevention of Preterm Birth. Number 130, October 2012.
ACOG Practice Bulletin: Premature Rupture of Membranes. Number 139, October 2013.
ACOG Practice Bulletin: Nausea and Vomiting of Pregnancy. Number 52, April 2004.
Cunningham, F., et al. Williams Obstetrics. 23rd ed. The Mcgraw Hill Companies, Inc. 2010.
Lockwood, C., et al. (2013). Prenatal care (second and third trimesters). Retrieved 12/7/2014 from http://www.UpToDate.com.
Riley, LE, and A.R. Stark. Guidelines for Perinatal Care. 7th ed. AAP and ACOG. 2012.