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

Abstract

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.