1 Center for Women's Reproductive Health, Birmingham, Alabama, United States; Department of Maternal Fetal Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States. Electronic address: cbmccarley@uabmc.edu.
2 Department of Biostatistics, Department of Biostatistics at University of Alabama at Birmingham, Birmingham, Alabama, United States.
3 Center for Women's Reproductive Health, Birmingham, Alabama, United States.
4 Center for Women's Reproductive Health, Birmingham, Alabama, United States; Department of Maternal Fetal Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States.