Conclusion
This study has shown that a large proportion of women increase their BMI, and a small proportion decrease their BMI between their first two pregnancies. Both increase and decrease in BMI between pregnancies were associated with higher risks of adverse outcomes in the second pregnancy. These findings highlight the importance of returning to pre-pregnancy weight and maintaining a stable interpregnancy BMI thereafter, to achieve better pregnancy outcomes subsequently. However, the recommended magnitude of weight loss beyond their pre-pregnancy weight remains unclear, especially for those who are overweight or obese, where a loss >1 kg/m2 was associated with SGA and low birthweight. Future studies should examine the role of interpregnancy lifestyle interventions in maintaining a stable interpregnancy BMI among Asian women, and more importantly, the role of metabolic health in adverse pregnancy outcomes with the measurement of body composition and metabolic biomarkers. This will shed light on possible aetiologies of low birthweight/SGA and weight loss and guide personalized interventions and BMI targets for women with lean BMI and those who are overweight or obese.