Background and Objective: Several studies have reported significant disturbances in vertical posture during various standing and walking conditions, but there is little evidence about the behavior of related muscles in dynamic conditions such as external perturbation, so this study was done to investigate and to compare the delay in response of upper trapezius and sternocleidomastoid muscles as two superficial muscles in the neck area, in posterior-anterior perturbation among patients with chronic neck pain and healthy subjects. Materials and Methods: This study was a case-control study with simple nonprobable sampling.32 subjects (16 healthy subjects and 16 patients with chronic neck pain) participated the study. Data collection was done using questionnaire and test performance .The equipments included dynamometer, chronometer and surface kinesiology electromyography .Dropping the weight equal to 10% of total body weight, performed using electrical magnet, followed by pulling of the trunk inducing perturbation was performed. Results: There were significant statistical differences in response onset of upper trapezius(p=0.032) and sternocleidomastoid(p=0.012) muscles between two groups.This meant the response onset in patients was longer than healthy subjects. Conclusion: Pain can change the onset of response of trapezius and sternocleidomastoid muscles and possibly decrease muscle activity in deep muscles and change the pattern of muscle activation and possibly it can increase the risk of injury in patients with chronic neck pain.

Background and Objective: Infant exposure to environmental tobacco smoke is a major public health problem. The aim of this study was to determine the effects of environmental tobacco smoke exposure on infant weight. Materials and Methods: This was a prospective cohort study. Participants of this study were 51 exposed and 51 non-exposed infants whose weight was measured in three periods of 5-7 days of age and also 2 and 4 months of age. Environmental tobacco smoke exposure of infants and their urinary cotinine were assessed by a questionnaire. The urine samples were collected during each follow-up. For data analysis, independent t test, chi-square and Fisher's Kappa tests were used. Results: Mean urinary cotinine levels over 5-7 days, 2 months and 4 months of age in the exposed group was significantly higher than in the non-exposed group (P<0.001). The mean weight of the exposed group was significantly lower than the non-exposed group in 2 and 4 months of age (P<0.001(. Conclusion: The results of this study show the weigh loss among infants exposed to environmental tobacco smoke, so we suggest further studies with longer follow-up periods and in all aspects of infants’ life.

Background and Objective: Child weight is considered as one of the most appropriate criteria for determining the nutritional status of the children particularly prior to 24 months of age. There is an association between duration of breastfeeding and child weight via which childhood and even adult obesity can be predicted. Regarding the importance of breastfeeding and its critical role in future health of children, the present research was carried out to investigate the association between the duration of exclusive breastfeeding and the weight of 24- month-old children in Zanjan province.

Materials and Methods: This cross-sectional research was carried out using the registered data from 24 months old children records in rural/ urban health centers of Zanjan province. The sampling included all records of neonates born from 2010 to 2012 which were selected using a multi-stage cluster sampling method. Data were assessed by ordinal regression with the Proportional odds model and chi-square test. Stata12 was used for data analysis.

Results: Of 8456 children with the age of 24 months, 4146 (49%) were female. The mean age of the mothers was 27.1±5.4 years. The mean duration of breastfeeding and exclusive breastfeeding with related standard deviation were 20.3±5.8 and 4.7±1.4 months, respectively. The mean and standard error concerning 24-month- old children’s weight was 11939±13.2 grams. There was an inverse relationship between the duration of breastfeeding and exclusive breastfeeding with 24-month-old children’s weight (p<0.001).

Conclusion: This study elucidates that continuation of breastfeeding until 24 months of age may prevent child obesity. Therefore, exclusive breastfeeding encouragement and the continued breastfeeding until 24 months are critically recommended.