Improving dietary energy and antioxidative properties benefit early maternal BMI and further manage adverse pregnancy outcomes with better weight gain.

Dietary characteristics affect maternal status in early pregnancy, which is important for later outcomes. However, Chinese dietary guidelines for pregnant women are not specific to obesity, overweight, and underweight. Moreover, since pregnancy is a prolonged process, an intermediate factor is needed to connect early maternal BMI with pregnancy outcomes. In this cohort of 1785 Chinese pregnant women from 2020 to 2022, 37.98% of participants had abnormal BMI in early pregnancy. A lower energy intake from carbohydrates (<50%) but higher intake from protein (>20%) and fat (>30%) resulted in excessive energy consumption, which was a risk factor for maternal obesity (adjusted OR (AOR): 1.49, 95%CI: 1.02-2.17) and overweight (AOR: 1.47, 95%CI: 1.00-2.18). Furthermore, the risk of maternal underweight was increased by a poor antioxidative diet (AOR: 2.80, 95%CI: 1.02-7.66) with a 20.28% lower intake of isoflavones and an imbalanced dietary structure (AOR: 3.95, 95%CI: 1.42-10.95) with less energy from fat (<20%) and unsaturated fatty acids (<3%). Following the timeline from gestation to delivery, early maternal obesity, overweight, and underweight increased the risk of abnormal body weight gain during pregnancy (AOR: 1.91-3.62, 95%CI: 1.20-6.12). Subsequently, abnormal weight gain further provoked adverse pregnancy outcomes, such as gestational diabetes mellitus, hypertensive disorders, cesarean section, and macrosomia (AOR, 1.33-2.58; 95%CI, 1.04-4.17). To minimize these threats, obese/overweight pregnant women in China might have more energy from carbohydrates (>65%) while reducing energy intake from protein (<10%) and fat (<20%). Meanwhile, underweight pregnant women are advised to increase their intake of dietary antioxidants (especially isoflavones) and consume more energy from fat (>30%) and unsaturated fatty acids (>11%). Finally, gestational body weight gain, as a potential intermediate bridge, should receive more attention.