Objective. To determine the ability of the back-scratch test during early second trimester of pregnancy to predict the odd of caesarean section and the need of oxytocin administration to induce or stimulate labour. Design. Longitudinal study. Population or sample: Pregnant women from the GESTAFIT Project (n=157). Main Outcome Measures. Maternal upper-body flexibility was assessed at 16th gestational week through the back-scratch test. Type of birth and oxytocin administration was registered from the obstetric medical records. Results. The receiver operating characteristic curve analysis showed that the back-scratch test was able to discriminate between vaginal and caesarean section deliveries (area under the curve [AUC]=0.672 (95% confidence interval [CI]:0.60-0.77, p=0.002)). The AUC to establish the ability of the back-scratch test to detect the need of oxytocin administration was 0.682 (95% CI:0.59-0.78, p=0.001). In the adjusted model, a back-scratch test score <4.1 centimetres was associated to ~4 times greater increased odd ratio of having a caesarean section (95% CI:1.7-10.2, p=0.002). A back-scratch test score <3.6 centimetres was associated to ~5 times greater increased odd ratio of requiring exogenous oxytocin administration (95% CI:2.0-11.6, p=0.001). Conclusion. The back-scratch test discriminates pregnant women with greater risk of caesarean section from those with a vaginal delivery, and among those that will require oxytocin from those that will not. The early identification of pregnant women who fail to meet the suggested standards can help to easily, quickly and cheaply identify these relevant birth-related complications in order to initiate preventive strategies. Keywords. Pregnant woman, upper-body flexibility, labour, obstetric risk.

Objectives: The aim of this study was to explore the associations of abdominal muscles thickness and inter-recti distance (IRD) at late pregnancy with birth-related outcomes and umbilical cord blood (CB) gas values. Design: cross-sectional study. Setting: Sport and Health University Research Institute Sample: One hundred and fifty-two pregnant women. Main outcome measures: The thickness of the abdominal muscles (transverse abdominis [TrA], internal [IO] and external obliques [EO]) and the IRD were measured by ultrasound at the 34th gestational week. Birth outcomes were collected from obstetric medical records. Umbilical CB gas concentrations were assessed after birth using a blood analyzer. Results: Greater TrA and IO thickness were associated with a higher venous CB PO2 value, both at muscular rest (respectively, p<0.01 and p<0.05) and during activation (both p<0.05). A greater activated TrA thickness was associated with a higher venous CB oxygen saturation (p<0.05). EO thickness at rest was positively related to arterial CB pH (p<0.05), and during activation to the 1-minute Apgar test (p<0.05). A greater IRD was associated with higher arterial (at rest p<0.01; during crunches p<0.05) and venous CB (at rest, p<0.05) PCO2 values, and with lower arterial CB PO2 (p<0.05), arterial CB oxygen saturation (at rest, p<0.05; during crunches p<0.01), and venous CB oxygen saturation (during crunches, p<0.05, and lower venous pH (p<0.05). Conclusion: Greater abdominal muscle thicknesses and a smaller IRD at late pregnancy are related to better umbilical CB gas values at birth. ClinicalTrials.gov Identifier: NCT02582567