We celebrate this 25th edition of Williams Obstetrics with greatappreciation for the insight and expertise that the early editorsbrought to this textbook. To pay tribute to the first author, J.Whitridge Williams, we begin each chapter with a passage fromhis 1st edition that complements the topic. During this selectionprocess, we were inspired by the strides that modernobstetrics has made since that edition in 1903. Similarly, wewere humbled by some of the classic challenges that still persist.Preterm labor, preeclampsia, and infections are some examples.That said, many of these advances were derived from rigorous,evidence-based research. And, we acknowledge and support thepower of this academic ideal to further our specialty in thedecades to come.Forthis 25th edition, we continue to present the detailedstaples of basic obstetrics such as maternal anatomy and physiology,preconceptional and prenatal care, labor, delivery, andthe puerperium.These accompany detailed discussions ofobstetrical complications exemplified by preterm labor, hemorrhage,hypertension, and many more. To emphasize the “M” inMaternal–Fetal Medicine,we continue to iterate the manymedical and surgical disorders that can complicate pregnancy.And,our second patient—the fetus—has accrued especialattention with an entire section devoted todiagnosis and treatmentof fetal disorders. For all of these, we once again emphasizethescience-based underpinnings of clinical obstetrics withspecial emphasis on biochemical andphysiological principles.As was the hallmark of previous editions, these dovetail withdescriptionsof evidence-based practices. Expert clinical pearlsadd depth to these discussions and are writtenfor busy practitioners—those “in the trenches.”To accomplish these goals, the text has beenupdated withmore than 3000 new literature citations through 2017. Manyof the nearly 900figures are new, and these graphs, sonograms,magnetic resonance images, photographs,photomicrographs,and data graphs are almost all in vivid color. Much of theoriginal artwork was rendered by our own medical illustrators.Also, as before, we continue to incorporatecontemporaneousguidelines from professional and academic organizationssuch as the AmericanCollege of Obstetricians and Gynecologists,the Society for Maternal–Fetal Medicine, theNationalInstitutes of Health and the National Institute for ChildHealth and Human Development,the Centers for DiseaseControl and Prevention, and other authoritative sources. Manyof thesedata are distilled into nearly 100 tables, in which informationhas been arranged in an easyread-and-use format. Inaddition, several diagnostic and management algorithms areavailable to quickly guide practitioners. Although we strive tocite numerous sources and provide multipleevidence-basedoptions for such management schemes, we also include ourown clinicalexperiences drawn from the large obstetrical serviceat Parkland Hospital. We are convinced thatthese aredisciplined examples of evidence-based obstetrics but quicklyacknowledge that they donot constitute the sole method ofmanagement.

F. Gary Cunningham

Kenneth J. Leveno

Steven L. Bloom

Jodi S. Dashe

Barbara L. Hoffman

Brian M. Casey

Catherine Y. Spong