Investigation of optimal range of gestational weight gain for twin pregnancies according to Chinese specific body mass index categories

BACKGROUND: There is a lack of data on the optimal gestational weight gain (GWG) in twin pregnancies in China. METHODS: A multicenter retrospective study was conducted, containing 1247 twin pregnancies in both North and South China. Optimal GWG was defined as the interquartile range of GWG across pre-pregnancy body mass index stratum among low-risk women. The composite outcome was defined as any occurrence of preterm delivery, small for gestational age, large for gestational age, and hypertensive disorders during pregnancy. RESULTS: The study found that the optimal total gestational weight gain was 16-21.80 kg for underweight, 15.35-21.50 kg for normal weight, 12.10-20.25 kg for overweight, and 5.50-18.50 kg for obese subgroups. Corresponding gestational weight gain 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. The proposed gestational weight gain ranges by our study were lower than the provisional Institute of Medicine (IOM) twin recommendation but higher than the Chinese Nutrition Society's singleton recommendation. Additionally, 46.11% of participants gained appropriate weight according to our suggestion, compared to 43.48% and 23.82% for the Institute of Medicine of twin guideline and the Chinese Nutrition Society's singleton recommendation, respectively. Furthermore, the 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, regional differences were observed. Southern Chinese women had a lower prevalence of adverse outcomes with proposed appropriate GWG ranges (80.78%) compared to the IOM twin guideline (82.04%). while northern women showed a slightly higher incidence of adverse outcomes under the proposed guidelines (65.67%) versus the IOM guideline (64.46%). Meanwhile, insufficient GWG was also more strongly linked to adverse outcomes in northern women (adjusted OR = 2.35) compared to southern women (adjusted OR = 1.15). These results indicating that northern women may need a higher optimal GWG threshold. CONCLUSION: Our study emphasizes the necessity of establishing official gestational weight gain guideline for Chinese twin pregnancies, and regional-specific guidelines may need to be considered.