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Objective: To analyze the status of gestational weight gain (GWG) among Chinese mothers who gave singleton and full-term births, and to look at optimal GWG ranges. Methods: In 2013, using the multi-stage stratified and population proportional cluster sampling method, we investigated 8 323 mother-child pairs at their 0-24 months postpartum from 55 counties (cities/districts) of 30 provinces (except Tibet) in mainland China. Questionnaire was used to collect data on body weight before pregnancy and delivery, diseases during gestation, hemorrhage or not at postpartum, child birth weight and length, and other information about pregnant outcomes. We measured mother's body weight and height, and child's body weight and length. Based on 'Chinese Adult Body Weight Standard', we divided mothers into four groups according to their body weight before pregnancy: low weight (BMI<18.5 kg/m(2)), normal weight (BMI 18.5-23.9 kg/m(2)), overweight (BMI 24.0-27.9 kg/m(2)) and obesity (BMI≥28.0 kg/m(2)). The status of GWG was assessed by IOM optimal GWG guidelines. Chinese optimal GWG ranges were calculated according to the association of GWG with pregnant outcomes and anthropometry of mothers and children, and according to P25-P75 of GWG among mothers who had good pregnant outcomes and good anthropometry, and whose children had good anthropometry. The status of GWG was assessed by the new optimal ranges. Results: P50 (P25-P75) of GWG among the 8 323 mothers was 15.0 (10.0-19.0) kg. According to the proposed optimal GWG ranges of IOM, the proportions of inadequate, optimal and excessive GWG accounted for 27.2% (2 263 mothers), 36.2% (3 016 mothers) and 36.6% (3 044 mothers). The optimal GWG ranges for low weight, normal weight, overweight and obesity were 11.5-18.0, 10.0-15.0, 8.0-14.0 and 5.0-11.5 kg. Based on these optimal GWG ranges established in this study, the rates of inadequate, optimal and excessive GWG were 15.7% (1 303 mothers), 45.0% (3 744 mothers) and 39.3% (3 276 mothers), and these rates were significantly different from that defined by the IOM standards (χ2=345.36, P<0.001). Conclusion: The median of GWG among Chinese mothers is 15.0 kg, which is at a relatively higher level. This study suggests the optimal GWG ranges for Chinese women who give singleton and full-term babies, which appears lower than IOM's.

Objective: To assess the dietary intake status of Chinese lactating women during the first month postpartum. Methods: Data were extracted from Chinese National Nutrition and Health Surveillance, children aged 0-5 years and lactating women (2013). A total of 55 counties from 30 provinces in China (excluding the Tibet Autonomous Region) were selected using a multi-stage stratified cluster randomization sampling method. A group of 3 623 lactating women, at 1-6 months after delivery, were investigated in the study. The semi-quantitative food frequency questionnaire (FFQ) was used to collect information on frequencies and amounts of food consumed. Differences in food consumption rates and dietary intake in lactating women having different characteristics were analyzed and compared. Results: To eliminate abnormal values, 3 300 lactating women were included in the study. During the first month postpartum, food types with higher consumption rates were animal products (98.2%, 3 239) and vegetables (90.7%, 2 987), in addition to cereals (100%) and liquids (100%). The consumption rate of fruits was 67.4% (2 222) and the lowest consumption rate was for dairy products (38.3%, 1 262). The median intake of cereals, vegetables, fruits and animal products were 247.8, 150.0, 40.0 and 178.6 g/d, respectively. The daily median intake of dairy products and soybean/nut products was 0.0 g/d. Overall, the lactating women consumed 895.7 ml/d liquids. About 49.3% (1 627) of the subjects consumed less than the recommended intake for animal products in Chinese Dietary Guideline (2016). More than 50% of the lactating women consumed less than the recommended intakes for the other types of food, especially dairy, soybean/nut and liquids. The consumption rates for dairy products were 26.9%, 29.4%, 31.8% and 33.8% and those for soybean/nut products were 33.9% , 35.8% , 37.5% and 41.7% for the lactating women living in rural areas, with educations at junior high school level and below, with average family incomes under 15 000 yuan per capita in 2012 and who work as household mothers, respectively. These consumption rates for dairy and soybean/nuts were significantly lower than those in women living in cities (48.4%, 55.0%), with an education level of senior high school or above (48.8%, 55.7%), with average family income over 15 000 yuan per capita in 2012 (45.5%, 52.8%) and who work outside the home (43.7%, 49.4%). P values were <0.05 for all comparisons. Conclusion: The daily intake of all foods by lactating women during the first month postpartum was lower than the levels recommended in Chinese Dietary Guideline (2016). The consumption rate of dairy and soybean/nut products during this time period was low, especially for those living in rural areas, with education levels of junior high school and below, with average family incomes less than 15 000 yuan per capita in 2012 and who are housemothers.

Objective: The study aimed to assess the folic acid status of lactating women in China and to analyze factors related to folic acid deficiency in these subjects. Methods: The data on lactating women were extracted from the Chinese National Nutrition and Health Surveillance in 2013. By a multi-stage stratified cluster random sampling method, 10 331 lactating women were selected for the study. The lactating women, 0-24 months postpartum, were from 55 sites in 30 provinces of China, excluding the Tibet Autonomous Region. A standard questionnaire was used to obtain general information and dietary intake during the previous one month period was collected using a food frequency questionnaire. A total of 20% of the total number of lactating women were randomly selected to analyze serum folic acid. Finally, 1 894 lactating women, with questionnaire results and serum folic acid data, were included in the study. Serum folic acid concentrations were analyzed using an electro-chemiluminescence immunoassay method. Folic acid deficiency was defined as a serum folic acid level <2 ng/ml. A multiple logistic regression analysis was used to analyze the factors associated with folic acid deficiency in these women. Results: After excluding abnormal values, 1 894 lactating women were included in the study. Based on our findings, the prevalence of folate deficiency was 3.0% (56/1 894) in lactating women in China. The prevalence of folic acid deficiency was 0.3% (1/388), 1.3% (7/550), 6.0% (38/639) and 3.2% (10/317) in larger, medium or small cities, general rural counties and poor rural counties, respectively. The prevalence of folic acid deficiency was 6.3% (17/269) and 2.4% (39/1 623) for minority and Han ethnic groups, respectively, and was 6.3% (52/823) and 0.4% (4/1 071) for subjects in northern and southern areas of China, respectively. Binary unconditionally logistic regression was used to analyze the factors associated with folic acid deficiency in the lactating women. The results showed that, compared with those living in the south and those in the Han ethnic group, those living in the north and belonging to the minority ethnic group had a greater risk of folic acid deficiency, with ( OR= 3.63, 95 % CI: 1.64-8.05) and ( OR= 5.42, 95 % CI: 1.75-16.74), respectively. With each month of age during childhood, the prevalence of folic acid deficiency decreased by 10% ( OR= 0.90, 95 %CI: 0.85-0.96). Compared with low income subjects, those with middle incomes had OR (95 %CI ) of 0.25 (0.10-0.60) for folic acid deficiency. A lesser intake of cereal was associated with a greater risk of folic acid deficiency in lactating women ( OR= 3.04, 95 %CI: 1.18-7.79). A lesser intake of tubers was a protective factor for folic acid deficiency in lactating women ( OR= 0.29, 95 % CI: 0.12-0.70). Conclusion: The folic acid status of Chinese lactating women has, in general, recently improved. However, living in northern areas, during early lactating periods, belonging to an ethnic minority, living in rural areas, having a low income, lower intake of cereal and excessive intake of tubers were risk factors for folic acid deficiency in lactating women. In these women, folic acid intervention should be considered a priority.

Objective: To analyze the status of postpartum weight retention and its associated factors among Chinese lactating women in 2013. Methods: This study was based on the databank of Chinese National Nutrition and Health Surveillance in 2013. Using the multi-stage stratified cluster sampling method, we enrolled 12 514 women, at 0-24 months postpartum, from 55 sites in 30 provinces of China (excluding the Tibet Autonomous Region). Questionnaires were used to collect data on basic characteristics, physical activity, lifestyle, food intake, pre-pregnancy weight, weight before delivery, disease history during pregnancy, delivery date, delivery mode, parity and breastfeeding information. Current body weight and height of each subject were measured. Postpartum weight retention in each subject was calculated as the difference between pre-pregnancy and current weights. High postpartum weight retention was defined as ≥5 kg. Survey sample weights were calculated according to the sampling design and number of children under 2 years old from 2010 population census data of China. Associated factors of high postpartum weight retention were identified by multiple logistic regression analysis. Results: A total of 9 972 women were included in this study. P 50 ( P 25 - P 75 ) of weight retention for participants was 3.6 (0.2-7.3) kg and high weight retention accounted for 41.5% of the subjects (4 134/9 972). The weighted means (SE) of weight retention was 3.5 (0.1) kg, and it was at 0 to <3, 3 to <6, 6 to <9, 9 to <12, 12 to <18 and 18 to <24 months postpartum were 5.3 (0.2), 4.5 (0.2), 3.8 (0.2), 3.1 (0.2), 2.8 (0.2) and 3.0 (0.2) kg, respectively. The weighted proportion of high postpartum weight retention was 37.4% (95% CI: 36.0%-38.9%). Compared with women aged under 25 years old, the odds ratio of high postpartum weight retention was 1.31 for women over 30 years old. Compared with women at 18 to <24 months postpartum, the odds ratio of high postpartum weight retention was 2.67, 1.61 and 1.31 for women at 0 to <3, 3 to <6 and 6 to <9 months postpartum, respectively. Compared with women having a pre-pregnant BMI from 18.5 to <25.0 kg/m 2 , the odds ratio of high postpartum weight retention was 1.30 and 0.67 for women having pre-pregnant BMI <18.5 kg/m 2 and ≥25.0 kg/m 2 , respectively. Compared with women having appropriate gestational weight gain, the odds ratio of high postpartum weight retention was 0.47 and 2.24 for women having low and excessive gestational weight gains, respectively. Compared with farmers, the odds ratio of high postpartum weight retention was 1.44 for housewives. ( P< 0.05 for all comparisons). Conclusion: Postpartum weight retention in Chinese lactating women is at an intermediate level. High postpartum weight retention is primarily associated with age, postpartum period, pre-pregnant BMI, gestational weight gain and career. The key control factor for weight retention is gestational weight gain, and 1 year postpartum is critical period for weight recovery.

Objective: To analyze serum vitamin D levels in Chinese lactating women, in 2013, and to evaluate their vitamin D nutritional status and influencing factors. Methods: Data were from the Chinese National Nutrition and Health Surveillance in 2013. Using the multistage stratified cluster sampling method, serum samples from lactating women, at 0-24 months postpartum, were obtained from 55 sites in 30 provinces of China, excluding the Tibet Autonomous Region. The concentration of serum vitamin D was determined by mass spectroscopy. A standard questionnaire was used to obtain basic information and the season of blood collection. Dietary information for one recent month was collected using a food frequency questionnaire. A total of 1 981 lactating women were included in the study. A multiple logistic regression model was used to analyze the factors related to vitamin D levels among lactating women. Results: The mean vitamin D level was (16.6±6.5) ng/ml, the prevalence of vitamin D deficiency (VDD) (vitamin D<12 ng/ml) was 25.2% (499 cases) and the prevalence of vitamin D inadequacy (12 ng/ml≤vitamin D<20 ng/ml) was 45.4% (900 cases). Compared with in the Han ethnic group, the OR value of VDD was 13.37 for Muslim ethnic women. Compared with women having a junior high school education or below, the OR value of VDD was 1.40 for those women with an educational level of senior high, middle school or above. Compared with housewives or nonworking women, the OR value of VDD was 1.62 for professional women. Compared with women living in general rural settings, the OR values of VDD for women living in large cities, medium and small cities or poor rural settings were 1.99, 1.46 and 2.66 respectively. Compared with the women surveyed in the fall, the OR value of VDD was 2.19 for the women surveyed in winter or spring. The VDD prevalence increased with higher latitude ( OR= 1.12) and decreased with increased meat consumption per day ( OR= 0.73). ( P< 0.05 for all comparisons). Conclusion: Vitamin D deficiency and vitamin D inadequacy were common in lactating women in China. Those with increased risk of VDD included lactating women who were ethnic Muslims, with higher education levels, engaged in a professional occupation, living in higher latitude region and were surveyed in winter and spring.