[External fetal electrocardiograms with P wave. Report of 6 cases]

The purpose of this report is to present six pregnancies in which by means of external fetal electrocardiography, besides the feto-maternal QRS complexes, a clear fetal P wave can be identified. The number of electrocardiograms taken per patient was of one or more. In one of the cases this finding has persisted from the 26th to the 30th weeks of pregnancy. When analyzing the clinical characteristics of the cases, the only commun finding was that each one of the pregnancies averaged between nineteen and twenty six weeks of amenorrhea. Attention is called to search for the possible reasons by which commonly the fetal P wave can not be detected. Findings of other authors are discussed.