Differences and Correlation Analysis of Birth Weight and Overweight/Obesity in Shanghai Twin Cohort.

The objective of this study was to analyze differences in birth weight and overweight/obesity in a Shanghai twin cohort. We also wanted to study their association and explore possible risk factors for the discordance of overweight/obesity within twins. This was an internal case-control study designed for twins. The 2012 Shanghai Twin Registration System baseline survey data of a total of 3417 twin pairs were statistically analyzed using SPSS22 software. Results show that the body mass index (BMI) of the Shanghai twin population increased with age. Twins with a high birth weight had a higher BMI and a higher rate of overweight and obesity; 0- to 6-year-old twins, male twins and dizygotic (DZ) twins had higher rates of overweight/obesity than other groups. The greater the discordant birth weight rate of twins, the more obvious the difference in BMI (p < .05). There was a significant difference in overweight/obesity between twins with a relative difference of birth weight ≥15% in DZ twins (p < .05). DZ twins, male twins and 0- to 6-year-old twins were more likely to be discordant in overweight/obese than others. The discordant birth weight within twins was not a risk factor for discordant overweight/obesity. However, attention should be paid to childhood obesity, and appropriate interventions should be made at the appropriate time. Genetics may play an important role in the occurrence and development of overweight/obesity. In conclusion, discordant growth and development in the uterus early in life may not lead to discordant weight development in the future.

Association of birth defects with the mode of assisted reproductive technology in a Chinese data-linkage cohort.

OBJECTIVE: To evaluate the impact of assisted reproductive technology (ART) on the offspring of Chinese population. DESIGN: Retrospective, data-linkage cohort. SETTING: Not applicable. PATIENT(S): Live births resulting from ART or natural conception. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Birth defects coded according to ICD-10. RESULT(S): Births after ART were more likely to be female and multiple births, especially after intracytoplasmic sperm injection (ICSI). ART was associated with a significantly increased risk of birth defects, especially, among singleton births, a significantly increased risk in fresh-embryo cycles after in vitro fertilization (IVF) and frozen-embryo cycles after ICSI. Associations between ART and multiple defects, between ART and gastrointestinal malformation, genital organs malformation, and musculoskeletal malformation among singleton births, and between ART and cardiac septa malformation among multiple births were observed. CONCLUSION(S): This study suggests that ART increases the risk of birth defects. Subgroup analyses indicate higher risk for both fresh and frozen embryos, although nonsignificantly for frozen embryos after IVF and for fresh embryos were presented with low power. Larger sample size research is needed to clarify effects from fresh- or frozen-embryo cycles after IVF and ICSI.