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Angiogenic Factors Changes Prior to the Onset of Spontaneous
Labor at Term: A Longitudinal Study
Puntabut Warintaksa1, Maolee Bhuwapathanapun1, Rakruthai Thongchai2, Suwatcharaporn Hadradchai1
,
Piya Chaemsaithong1*
1 Department of Obstetrics and Gynaecology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University
2 Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University
*Corresponding Author E-mail: pchaemsa@hotmail.com
Background: Abstract
Evidence suggests that the onset of labor is associated with changes in placental function.
Maternal circulating soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor
(PlGF) are the biomarkers for syncytiotrophoblast function. This study aims to determine
whether there are changes in maternal circulating sFlt-1 and PlGF concentrations prior to
the spontaneous onset of labor.
Methods: We conducted a longitudinal study by serially measuring maternal plasma concentrations
of sFlt-1and PlGF every 3-4 days from 37 weeks of gestation and every 2-3 days after 38
weeks until the spontaneous onset of labor in patients with uncomplicated pregnancies
(n=78). Maternal plasma concentrations of sFlt-1,PlGF, and sFlt-1/PlGF ratio changes were
analyzed using linear mixed-effects models.
Results: 1) Changes in PlGF and sFlt-1 in maternal circulation were detected immediately before the
spontaneous onset of labor. Specifically, PlGF and PlGF/sFlt-1 ratio decreased by 2.4% and
4.3%, respectively, whereas sFlt-1 increased by 1.9% with each additional day; and 2) a
significant difference in the rate of changes of angiogenic factors between the multiparous
and nulliparous women was observed. Multiparous women had higher maternal plasma
PlGF concentrations at 37 weeks of gestation and a faster rate of PlGF reduction (2.1%)
compared to nulliparous women.
Conclusion: Changes in maternal sFlt-1 and PlGF concentrations precede the spontaneous labor onset
at term, suggesting an alteration in placental function before the onset of labor. Nulliparous
women exhibit lower PlGF concentrations compared to multiparous women, suggesting an
anti-angiogenic state.
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