Subjects and methods Families (N = 124) were initially recruited and assessed between October and December 2007 during their labor visit to the birth hospital. They were invited for a follow-up visit approximately 14 months later, between February and March 2009. The recruitment of families has been described in detail

elsewhere [10]. Only primiparous mothers who were BIX 1294 mw healthy, non-smoking, aged between 20 and 40 years, of Caucasian origin, and had an uneventful, singleton, full-term pregnancy (37–42 weeks) were included. The study protocol was approved by the Ethics Committee of Helsinki University Hospital. All mothers gave their written informed consent in accordance with the Declaration AC220 datasheet of Helsinki. Maternal vitamin D status was assessed in communal prenatal clinics during the first trimesters as part of normal follow-up. A second, fasting blood sample from the mother was collected 2 days postpartum during the hospital stay between late October and mid-December 2007. At birth, cord blood was obtained from the umbilical vein after cord clamping in 81 subjects. Background data was collected through an extensive questionnaire. Records on pregnancy follow-up and the birth report were obtained, including birth weight, length and head circumference measured by midwifes, and duration of the pregnancy. Birth lengths and weights were transformed into Z-scores

using Finnish Tubastatin A concentration sex-specific normative data for fetal growth [21]. One newborn and her mother were excluded from the initial analysis due to intrauterine growth retardation. Eighty-seven (70%) of the original cohort of 124 families 3-mercaptopyruvate sulfurtransferase agreed to participate in the follow-up visit. Mothers in families agreed on follow-up tended to be younger (p < 0.1), they were more educated (p = 0.09) and had smaller family (p = 0.08) than non-participants, but there were no differences in any pregnancy outcomes. Before the 14-month visit, the families received an extensive questionnaire concerning the child’s health and medical history, sunshine exposure, and

use of vitamin supplements. The questionnaire included a 3-day food record. During the study visit, one of the researchers interviewed the family about the child’s development, including motor and language skills. Of those who agreed to participate in the follow-up visit, all but three returned the questionnaire. Anthropometric measurements were obtained for each subject. Height was measured at standing position with a wall-mounted height measuring scale and rounded to the nearest 0.1 cm. Weight was measured while sitting on a scale in light clothing and rounded to the nearest 0.1 kg. Heights were transformed into Z-scores and weights were expressed as height-adjusted weights according to Finnish sex-specific normative data for infants [21].