Labor National Center for Biotechnology Information NCBI NLM MEDLINE humans pubmed abstract nih national institutes of health national library of medicine pregnancy research support adult female N.I.H. Extramural Infant newborn Incidence Retrospective Studies Cohort Studies risk fetal diseases / etiology placenta / blood supply small for gestational age cesarean section* / statistics & numerical data pregnancy complications / etiology pregnancy complications / therapy* pmid:17014813 doi:10.1016/j.ajog.2006.05.021 cande v ananth anthony m vintzileos abruptio placentae / epidemiology abruptio placentae / therapy fetal diseases / therapy* fetal distress / epidemiology fetal distress / therapy ischemia / complications induced* / statistics & numerical data pre-eclampsia / epidemiology pre-eclampsia / therapy premature birth* / epidemiology premature birth* / etiology