Correlation Between Gestational Weight Gain and Low Back Pain in the Third Trimester: A Cross-Sectional Study

Pregnancy involves physiological changes that may lead to low back pain (LBP), especially in the third trimester. Excessive gestational weight gain (GWG) has been suggested as a contributing factor, but evidence in low-income populations is scarce. This study is aimed at correlating GWG with LBP in the third trimester among postpartum women in São Paulo, Brazil.

This cross-sectional study included 53 postpartum women (18-42 years of age) from a public hospital in São Paulo. Data on sociodemographics, GWG, and LBP (visual analog scale, and body map) were collected. Statistical tests included t-test, Mann-Whitney, ANOVA, chi-square, and linear regression (α = 0.05, two-sided).

Mean age was 28.2 years; 77.3% reported LBP, 53.7% with severe pain (VAS ≥ 6). Mean GWG was 12 kg. Women with severe pain had higher absolute weight gain (14.7 kg vs. 10.3 kg; p = 0.028) but no significant difference in weight progression across trimesters. Linear regression showed no causal relationship between pain intensity and GWG alone (p = 0.463). Manual workers tended to have more severe pain (70.6% vs. 29.4%; p = 0.067).

LBP was highly prevalent (77.3%) and clinically relevant. Higher absolute GWG was associated with greater pain severity, but no independent causal relationship was found. Multifactorial factors, including occupational demands, may mediate this association. Nutritional monitoring and multidisciplinary prenatal care are recommended.