Association of Optimal Gestational Weight Gain with Pregnancy Outcomes in Twin Pregnancies in China：A Multicenter Retrospective Study

Background: There is no well-established gestational weight gain (GWG) guideline for twin pregnancies in China. Methods: A multicenter retrospective study containing 1247 twin pregnancies was conducted in both North and South China. Optimal GWG was defined as the interquartile range (IQR) of GWG across pre-pregnancy body mass index stratum among low-risk women. A primary outcome is defined as any occurrence of preterm delivery, small for gestational age, large for gestational age and hypertensive disorders during pregnancy. Results: On the basis of 203 low-risk participants, we found that the optimal total GWG were 16-21.80 kg, 15.35-21.50 kg, 12.10-20.25 kg, and 5.50-18.50 kg for underweight, normal weight, overweight and obese subgroups, respectively; corresponding GWG rates were 0.43-0.61 kg/week, 0.42-0.59 kg/week, 0.34-0.55 kg/week, and 0.15-0.51 kg/week. Our proposed GWG ranges are lower than the provisional Institute of Medicine (IOM) twin recommendation but higher than the Chinese Nutrition Society (CNS) singleton recommendation. In addition, 46.11% of participants gain appropriate weight according to our suggestion, in contrast to 43.48% and 23.82% for the IOM twin guideline and the CNS singleton recommendation, respectively. Furthermore, the magnitude of association between the composite outcome with insufficient GWG defined by our suggestion was the strongest [adjusted odds ratio (95% confidence interval) =1.74 (1.21-2.49)] among recommendations. Noteworthy, the IQRs produced by our study seems to be superior to the IOM twin guideline in southern Chinese but not in northern Chinese. Conclusion: Our study emphasizes the necessity of establishing official GWG guideline for Chinese twin pregnancies, and regional-specific guidelines may need to be considered.