Contractile properties of multiple pregnancy myometrium


Ballard, Celia Contractile properties of multiple pregnancy myometrium. Master of Philosophy thesis, University of Liverpool.

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Abstract

Multiple pregnancies are associated with higher rates of perinatal mortality than singleton pregnancies. This is due to the higher rates of preterm delivery and its associated complications. However it is not understood why there is a difference in gestation and what mechanism is responsible for this. This thesis explores the possible different myometrial properties between multiple pregnancies and singletons, and the effect of progesterone on the uterine contractility by placing myometrial strips onto a force transducer, which recorded the trace reflecting the contractility of the strip. In a physiological saline solution there were no significant differences between the myometrial contractility properties of multiple pregnancies and singletons. The effect of progesterone showed a dose response relationship in singleton and twin myometrium as when incremental doses of progesterone were applied, greater amounts of reduction in force was exhibited. It was found that there were significant differences between twin and singleton myometrium at 10, 100μM progesterone with there being a significantly greater effect in singleton myometrium. This reduced effect in twins may explain why there was no effect found to prevent preterm birth in twins (Norman et al 2008), and suggests that a higher dose may have more beneficial in twins A possible explanation for this difference in non genomic action could be due to the greater quantities of stretch applied to twin myometrium earlier on in pregnancy, and this reducing the expression of the progesterone membrane receptor. This possible theory was explored by applied stretch on myometrial strips in 100μM progesterone. Although the paired stretched samples displayed a smaller response to progesterone, this was however not significant. Preterm delivery could also be affected by the maternal diet, as poor maternal nutrition leads to poor intrauterine growth, and is more likely to be preterm. A literature search was performed for studies that focused on maternal nutrition, and weight gain. It was found that early weight gain was associated with larger birthweights, and that total weight gain should be directed by maternal Body Mass Index (BMI), however much work is still required to explore how much weight gain is required, due to successful varying suggestions. It became apparent that when dietary supports (e.g. dieticians) were used, there were smaller rates of preterm delivery and preterm birth. Yet it was hard to clarify if this success was down to the dietary interventions or the content of the diet itself. This work has shown that twin and singleton myometrium respond differently to progesterone which plays a key role in uterine quiescence. This difference in response maybe the underlying trigger for preterm labor and that to improve the rates of preterm delivery we also need to think about the mother’s diet as well.

Item Type: Thesis (Master of Philosophy)
Additional Information: Date: 2010-08 (completed)
Subjects: ?? RG ??
Divisions: Faculty of Health and Life Sciences
Depositing User: Symplectic Admin
Date Deposited: 04 Jan 2011 10:04
Last Modified: 16 Dec 2022 04:34
DOI: 10.17638/00001460
Supervisors:
URI: https://livrepository.liverpool.ac.uk/id/eprint/1460
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