This is a prospective observational study on normal singleton pregnant women who have no sign of labor at 40 weeks of gestation or pregnant women who admitted to hospital for any sign of labor at term, aiming to identify labor-associated markers.

The mechanisms that instigate human parturition have not been completely understood, though hypotheses such as 'functional progesterone withdrawal' and inflammatory signaling have been proposed. Researchers including our group have previously identified panels of genes which were differentially expressed between placentas obtained after spontaneous birth and those after elective cesarean delivery. However, such findings obtained after birth could only reflects the late changes in parturition. Similar findings in other gestational tissues, such as fetal membranes, amniotic fluids, myometrial biopsies are available, but these sample types cannot be readily collected until delivery.

Thus, we propose to explore biomarkers in maternal blood with a view to developing any useful analytes for predicting labor.

Inclusion Criteria:

Healthy women who are carrying a healthy singleton pregnancy, but have not yet gone to labor at 40 weeks of gestation or who are at term and admitted to hospital for any sign of labor are invited to join the study.

Exclusion Criteria:

• Any obstetric contraindications for undergoing labor or vaginal delivery (e.g. placenta previa, cephalo-pelvic disproportion, macrosomia, previous classical cesarean section or uterine tear, etc).
• Any maternal or fetal complications that require immediate or early delivery (e.g. pre-eclampsia, abruption placenta, fetal distress, rupture of membranes, in utero death, etc).
• Any maternal or fetal complications that make vaginal birth an unfavorable choice (e.g. fetal growth restriction, fetal compromise or distress, etc).
• Any conditions that are known to affect the onset of labor (e.g. anencephaly).

Pregnant women

Healthy women who are carrying a healthy singleton pregnancy, but have not yet gone to labor at 40 weeks of gestation or who are at term and admitted to hospital for any sign of labor.