Association Between Maternal Creatinine to Body Weight Ratio and Small/Large for Gestational Age Newborns Among 11,734 Chinese Women.

BACKGROUND

Serum creatinine to body weight ratio (CBWR) is closely associated with non-alcoholic fatty liver disease, diabetes, and all-cause mortality. This study aimed to assess the impact of CBWR in late pregnancy on incident small and large for gestational age (SGA/LGA) deliveries.

METHODS

This observational study included 11,734 pregnant women with hospital-based hepatic/renal data (2016-2017). Demographic characteristics were compared between CBWR quintiles using appropriate parametric or nonparametric tests. Relationship between CBWR and clinical/laboratory parameters was assessed using Spearman's correlation. Linear regression was employed to evaluate the association of CBWR with fetal birth length/weight, while logistic regression was used to calculate adjusted odds ratios (ORs) for SGA/LGA, with both models adjusting for maternal age, parity, blood pressure, gestational week, assisted reproduction, neonatal sex, and laboratory results. Sensitivity analyses and subgroup stratifications confirmed these associations. Non-linear trends were explored using smooth curve fitting techniques.

RESULTS

Among these newborns, 1033 (8.80%) were classified as SGA and 1,827 (15.57%) as LGA. CBWR was associated with smaller birth length (β = -0.21 cm; 95% CI: -0.28, -0.15) and lower birth weight (β = -0.29 kg; 95% CI: -0.31, -0.27) in the highest versus lowest quintile. The multivariate-adjusted ORs of SGA in higher quintiles versus the lowest quintile of CBWR were 1.63 (95% CI: 1.21, 2.21), 2.16 (95% CI: 1.61, 2.89), 2.99 (95% CI: 2.25, 3.97), and 5.24 (95% CI: 3.97, 6.92), respectively; those for LGA were 0.60 (95% CI: 0.52, 0.70), 0.53 (95% CI: 0.46, 0.62), 0.39 (95% CI: 0.32, 0.46), and 0.23 (95% CI: 0.19, 0.29), respectively. Per standard deviation (SD) increase in CBWR was accompanied by a 1.63-fold increase in SGA risk (OR = 1.63, 95% CI: 1.52, 1.75) and a 42% decrease in LGA risk (OR = 0.58, 95% CI: 0.55, 0.63). Sensitivity analysis confirmed the consistence of these findings. Subgroup analysis demonstrated that CBWR was strongly associated with SGA risk in women with CBWR > 0.98 umol/L/kg complicated by preeclampsia or preterm birth, while in those complicated by gestational diabetes mellitus, the association was attenuated.

CONCLUSION

Our findings suggest that elevated CBWR in late pregnancy may be associated with decreased LGA risk and increased SGA risk. While CBWR represents an easily measurable and cost-effective potential indicator, these observational results require validation in prospective, population-based studies before considering clinical application.