Delivery and Perinatal Outcomes Associated with Pregnancy-Related Low Back Pain in a Cohort of Physically Active Women

Pregnancy-related low back pain (LBP) is a highly prevalent condition with substantial consequences. However, its relationship with objective perinatal outcomes has been scarcely investigated. The aim of this study was to analyze the association between the presence and intensity of pregnancy-related LBP with delivery and perinatal outcomes. An analysis of a prospective cohort was performed including 147 physically active (PA) pregnant women, defined as those meeting the World Health Organization recommendations for PA (≥600 MET·min/week), assessed using the short version of the International PA Questionnaire. Participants were classified according to the presence (64.6%) or absence of LBP during pregnancy. Umbilical artery pH was significantly lower in neonates born to women with LBP compared with those without LBP (7.24 ± 0.10 vs. 7.29 ± 0.06; p < 0.001). Within the LBP group, higher pain intensity was moderately and inversely correlated with umbilical artery pH (Spearman ρ = −0.42, p = 0.037) and remained independently associated with lower umbilical artery pH values in multivariable linear regression analysis after adjustment for relevant maternal characteristics and PA. Apgar scores were globally normal, with no clinically relevant differences between groups. No significant differences were observed in other delivery and perinatal outcomes. These findings suggest an association between pregnancy-related LBP and subtle changes in fetal acid-base status at birth but should be interpreted cautiously from a clinical perspective.