Association between birthweight discordance and extrauterine growth restriction among preterm twins: a national multi-center study in China

Qian Chen¹Bijun Shi¹Lizi Lin²Danfang Lu³Shuhua Ren⁴Kang Huang⁵Wei Shen⁶Zhifeng Chen⁷Jin Liu⁸Zhenyu Liang⁹Guifang Li¹⁰Hong Jiang¹¹Hongping Rao¹²Jianwu Qiu¹³Xian Wei¹⁴Yayu Zhang¹⁵Xiaobo Lin¹⁶Haiyan Jiang⁵Shasha HAN¹⁷Fan Wang¹⁸Weixing Zhang¹⁹Xiufang Yang²⁰Yitong Wang²¹Niyang Lin²²Xiaohua Tan¹Qiliang Cui^1*

• ¹The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
• ²Sun Yat-Sen University, Guangzhou, China
• ³Peking University Third Hospital, Beijing, China
• ⁴Sichuan Jinxin Women's and Children's Hospital, Chengdu, China
• ⁵The Affiliated Hospital of Guizhou Medical University, Guiyang, China
• ⁶The Affiliated Women and Children's Hospital of Xiamen University, Xiamen, China
• ⁷The Tenth Affiliated Hospital of Southern Medical University, Dongguan, China
• ⁸Central Hospital of Shaoyang, Shaoyang, China
• ⁹Guangdong Second Provincial General Hospital, Guangzhou, China
• ¹⁰Cangzhou People's Hospital, Cangzhou, China
• ¹¹Affiliated Hospital of Yan an university, Yan’ an, China
• ¹²Huizhou Central People's Hospital, Huizhou, China
• ¹³Yuebei People's Hospital Affiliated to Shantou University School of Medicine, Shaoguan, China
• ¹⁴Xiaogan Central Hospital, Xiaogan, China
• ¹⁵The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
• ¹⁶The Second Affiliated Hospital of Shantou University Medical College, Shantou, China
• ¹⁷The First Affiliated Hospital of Jinan University, Guangzhou, China
• ¹⁸Lanzhou University Second Hospital, Lanzhou, China
• ¹⁹Xinxiang Central Hospital, Xinxiang, China
• ²⁰Zhongshan City People's Hospital, Zhongshan, China
• ²¹Binhaiwan Central Hospital of Dongguan, Dongguan, China
• ²²The First Affiliated Hospital of Shantou University Medical College, Shantou, China

Background: This multicenter study investigated the association between birthweight discordance (BWD) and extrauterine growth restriction (EUGR) in preterm twins, and evaluated the modifying role of small for gestational age (SGA). Methods: Data from 2,496 infants (1,248 twin pairs) admitted to 22 Chinese NICUs (2018-2020) were analyzed. BWD was calculated as the percentage difference in birthweight between larger and smaller twins, categorized into four groups (≤15%, 15%-20%, 20%-25%, >25%). EUGR was defined as discharge weight below the 10th percentile for corrected gestational age and sex (Fenton’s chart). A generalized linear mixed model was employed to analyze the association between BWD and EUGR. Modification analysis was performed to assess the effect of SGA on this association. Results: BWD of >25% was associated with a significantly increased risk of EUGR compared to BWD ≤15% (adjusted OR=1.59, 95% CI:1.05-2.41). Stratified analysis revealed a consistent association in SGA infants (OR=1.38, 95% CI:1.30-1.47). Conclusion: Findings highlight BWD as a critical risk factor for EUGR, particularly in SGA twins. This association suggests that future research should investigate whether tailored monitoring and nutritional interventions in NICUs could help mitigate these growth disparities.