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Updated: Aug 24, 2026

Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development
07:56

Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development

Published on: January 26, 2018

Serum relaxin in pregnancy

A H MacLennan, R Nicolson, R C Green

    Lancet (London, England)
    |August 2, 1986
    PubMed

    Serum relaxin immunoactivity was measured by means of a porcine radioimmunoassay in a cross-sectional study of 302 normal singleton pregnancies. Concentrations in the third trimester were lower than in early and mid pregnancy. At term, relaxin levels in patients who went into spontaneous labour within a week of sampling were significantly lower than in those who did not. However, relaxin levels were highest during labour and fell almost to non-pregnant levels by the third postnatal day. Levels in twin pregnancies in the third trimester were higher than those in singleton pregnancies. Serial samples from 4 patients with a history of premature labour showed declining, very low levels in the only patient who subsequently had a preterm delivery. These results are compatible with the proposed roles of relaxin during pregnancy: namely, to maintain myometrial quiescence, facilitate uterine stromal remodelling during uterine growth, and promote cervical ripening at the onset of parturition.

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