Premium
THE EFFECT OF LABOUR ON UTERINE BLOOD FLOW IN THE PREGNANT EWE
Author(s) -
Towell M. E.,
Liggins G. C.
Publication year - 1976
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1976.sp002331
Subject(s) - blood flow , obstetrics , flow (mathematics) , pregnancy , andrology , medicine , biology , mechanics , physics , genetics
The effect of labour on cardiac output and uterine blood flow was measured in pregnant ewes at a mean gestation of 124 days using radioactive microspheres labelled with 169 Yb and 85Sr. Labour was induced by a continuous infusion of ACTH into the foetal circulation. Cardiac output measured before ACTH infusion in seven ewes was 5234±175·9 ml./min (mean±S.E.) and total uterine blood flow was 732±57·9 ml./min (mean±S.E.). Measurements during labour in six ewes showed a significant increase in cardiac output to 6175±149·6 ml./min (P < 0·005) but no significant change in uterine blood flow. However, the partition of blood flow was altered; thus myometrial flow increased by 67% from 114±15·4 ml./min to 190±13·2 ml./min (P < 0·005) while placental blood flow decreased, although not significantly, from 618±55·9 ml./min to 575±40·7 ml./min. Similar changes were observed in one ewe in spontaneous labour at term and in another ewe receiving an infusion of 4 mg oestradiol 17β over a 24 hr period. It is concluded that labour is not associated with any major alternation in total uterine blood flow although myometrial blood flow is increased. It is not known whether this is due to the rise in circulating oestrogens which occurs prior to parturition in the ewe, or to other factors such as the work of uterine muscle during labour.