Data collected on maternal dietary exposures in the Danish National Birth Cohort

Abstract

Recent research suggests that the diet consumed in, or shortly before, pregnancy can potentially lead to maldevelopment and diseases in the offspring, which may become apparent at any time from the embryonic stage until old age. For example, maternal diet may affect the chance of twinning (and associated complications), malformation risk, brain development, and the offspring's fecundity and risk of contracting cardiovascular diseases and cancer in adult life. Prospectively designed longitudinal studies with sufficient size and data quality are much needed to substantiate or refute these hypotheses. At present, the Danish National Birth Cohort is likely to be the largest epidemiological database containing extensive information on maternal dietary exposures. By October 2002, 100 000 women had been recruited in early pregnancy, for long-term follow-up of themselves and their offspring. The present paper details the information available in the database on early nutritional exposures with emphasis on maternal dietary intake. We also present distributions of selected nutritional exposures.

Research Letter: Folic acid supplementation and intake of folate in pregnancy in relation to offspring risk of autism spectrum disorder

“…The DNBC included more than 100 000 pregnancies, and details of the cohort have been reported previously (Olsen et al 2001(Olsen et al , 2007; briefly, recruitment for the DNBC took place through the General Practitioners (GPs) when women consulted them for the first antenatal visit which, in Denmark, usually takes place during gestation weeks 6-10. The GP gave oral and written information about the DNBC and if the woman decided to participate, she was asked to send the completed recruitment form by post to the research centre in a pre-stamped envelope.…”

“…Data collection in the DNBC included a recruitment form, two telephone interviews (gestation weeks 12 and 30, approximately); a semiquantitative food frequency questionnaire (FFQ) that was mailed to women in gestation week 25 asking about food consumption and supplement use in the previous 4 weeks ( Olsen et al 2007); and two postpartum telephone interviews (6 and 18 months postpartum, approximately). The main data source for our study was the recruitment form, which among other components had a section asking women to report on supplements and medication used in the periconceptional period.…”

“…Also, in sensitivity analyses we tested an association of periconceptional vitamin B12 with ASD, as well as an interaction between periconceptional B12 and folic acid supplementation in association with ASD. In supplementary analyses using data from the midpregnancy FFQ, we compared users v. non-users of folic acid containing supplements (0, <400, 5400 µg/day), as well as groups of women categorized into quintiles of estimated dietary folate intake; a trend test was performed by entering the median in each quintile as a continuous variable in the model (Olsen et al 2007). …”

Relative validity of a semi-quantitative, web-based FFQ used in the ‘Snart Forældre’ cohort – a Danish study of diet and fertility

“…The semi-quantitative, web-based FFQ was based on the paper-based FFQ applied in the Danish National Birth Cohort (24) and the 'Diet, Cancer and Health' study (25) , and was updated using information on usual dietary intake in Danish women aged 18-49 years (26) to capture intakes of foods and nutrients in this age group. In the web-based FFQ, participants are asked to record their usual intakes of foods and drinks in the previous year.…”

“…The widespread use of the Internet (in 2012, 92 % of all 16-74-year-old citizens in Denmark had Internet access at home (23) ) thus enables web-based studies. To assess dietary intake among Danish women planning a pregnancy, we developed a web-based FFQ based on the FFQ used in the Danish National Birth Cohort study (24) , updated for our target population of reproductive age women. The aim of the present study was to assess the relative validity of the web-based FFQ using a 4 d food diary as reference.…”