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