[Association between seasonal patterns and birth weight]

Season of birth is one of the environmental factors that may affect birth weight. The aim of this study was to assess the relationship between seasonal patterns and birth weight in an educational center in Iran, 2010. In this cross sectional study, the check list was used for checking of 3076 women that delivered on vaginal method [NVD]. Exclusion criteria included twin delivery, intrauterine fetal death [IUFD], abortion in current pregnancy and delivery by caesarean. 81.2% women were primiparous and 53.3 percent of newborns were boys. The gestational age of 7.4, and 92.6 percent women was preterm and term, respectivly. Average neonatal birth weight was 3248.18 +/- 458 and women mean age was 25.33 +/- 5.7 years. There was a significant relationship between seasonal changes and the mean birth weight [P= 0.018] as the highest weight was in spring and lowest in summer. The highest average birth weight term was the 21 March to 20 April and the lowest month was the 23 August to 22 September [P = 0.064]. Although birth weight can be different with seasonal changes, the role of other environmental factors should not be ignored.

[Sampling in qualitative research: a guide for beginning]

Sampling in qualitative and quantitative research are very different, because it aims, gaining a deep understanding of the phenomenon is being investigated, rather than generalizing the results. Participants Selection in the qualitative study is done with aim of achieve the maximum information about the phenomenon under study. In quantitative research there is too much emphasis on a random selection, an equal chance for selection of all members of the research community, but in the qualitative study samples or participants are selected or invited. Purposive sampling that also is called purposeful or qualitative sampling that means purposeful selection of samples for acquiring knowledge or information. This type of sampling does not focus on developing the fixed and immutable rules or generalizing the results but try to better understand the phenomenon in special field. Purposive sampling consists of three main types including "Sampling to Achieve Representativeness or Comparability", "Sampling Special or Unique Cases" and "Sequential Sampling". Saturation in qualitative research as a method of sampling is considered the gold standard. In this paper, we tried to introduce the participant's selection methods and the differences between quantitative and qualitative method and the strategy for decision making about data saturation will be offered