Objective: To investigate the association of both maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with childhood overweight and adiposity in preschool children. Methods: A total of 4 303 preschool children aged 3-5 years were enrolled in our study during June and November 2016 in Guangzhou. Children defined as overweight and obesity were according to the criteria of WHO while weight status during maternal pre-pregnancy was using the China Adult Reference. Gestational weight gain was defined according to the Institute of Medicine guidelines. Results: After adjusting the possible confounding factors, results from the logistic regression analysis showed that both maternal pre-pregnancy overweight and obesity would increase the risk for both childhood overweight and obesity (OR=1.820, 95%CI: 1.368-2.422). The analysis of covariance results also showed that both maternal overweight and obesity before pregnancy and excessive maternal weight gain during pregnancy increased the BMI Z-score in children. Maternal GWG over the recommended level were associated with both the childhood overweight and obesity (OR=1.296, 95%CI: 1.007-1.667). Joint associations of pre-pregnancy BMI and inappropriate GWG were also noticed in the study. Stratified analysis was conducted in three groups according to the pre-pregnancy BMI of the mothers. Result showed that there was no statistical difference in the risks of either overweight or obesity in children (P>0.05). However, when compared to mothers with adequate pre-pregnancy higher BMI and adequate GWG, under the combination of high pre-pregnancy BMI and excessive GWG, their adverse effects on childhood overweight and obesity were much higher (OR=1.574, 95%CI: 1.029-2.409). Conclusions Both high pre-pregnancy BMI and inappropriate GWG were associated with greater BMI of their offspring. Pregnant women should follow the appropriate weight gain program and help their children to prevent from becoming obese.

Objective: To observe the root and root canal morphology of mandibular second molars in Western Guangxi by CBCT, to provide a reference for clinical diagnosis and treatment. Methods: In total, 564 patients′ 1 128 mandibular second molars that satisfy the inclusion criteria were analyzed with a planmecaromexis CBCT machine and its own image analysis software. The patients′ gender, age and ethnic differences in the root and canal morphology and the symmetry of the bilateral root and canal were statistically analyzed. Results: Among the 1 128 mandibular second molars, 662 were the Zhuang ethnic group and 384 were the Han ethnic group, and 82 were other ethnic groups; the double root type and C-shaped root type accounted for a relatively high proportion: 73.94% and 24.47%, respectively. The detection rates of the double root type were higher in males than in females (P < 0.05); the detection rates of the C-shaped root type were higher in females than in males (P <0.05); the root type of the teeth was mainly double-rooted in the Zhuang ethnic group (P<0.01). The incidence of type IV in the mesial root of the double root type mandibular second molar was the highest (P < 0.01), and the incidence of type I in the distal root was the highest (P < 0.01). The C-shaped root canal is more continuous at the mouth of the root canal, more downward corresponds to a worse continuity: in three different levels of root canal orifice, root middle and root apex, the root canal orifice is dominated by the C1 type, and both root middle and root apex are mainly C3-type (P < 0.01). The difference in symmetry of bilateral roots and root canals was statistically significant among different gender groups, age groups, and ethnic groups (P < 0.05): there were more males than females, the results in the 18-35-year-old group and the Zhuang ethnic group were higher. Conclusion The root and root canal morphology of mandibular second molars in western Guangxi people are complex and changeable. The roots are mainly double root type in the Han ethnic group and the Zhuang ethnic group. C-shaped roots are also common. The detection rate of C-shaped roots in the Zhuang ethnic group was higher, and the symmetry rate of bilateral roots and that of bilateral root canals was higher in the Zhuang ethnic group than in the Han ethnic group.