Maternal vaccination and preterm birth: using data mining as a screening tool.

OBJECTIVE: The main purpose of this study was to identify possible associations between medicines used in pregnancy and preterm deliveries using data mining as a screening tool. SETTINGS: Prospective cohort study. METHODS: We used data mining to identify possible correlates between preterm delivery and medicines used by 92,235 pregnant Danish women who took part in the Danish National Birth Cohort (DNBC). We then evaluated the association between one of the identified exposures (vaccination) and the risk for preterm birth by using logistic regression. The women were classified into groups according to their exposure to vaccination. The regression analyses were adjusted for the following covariates: parity, infant's gender, maternal Body-Mass Index (BMI), age, smoking, drinking, job, number of inhabitants in the place of residence, infections, diabetes, high blood pressure and preeclampsia. MAIN OUTCOME MEASURE: Preterm birth, a delivery occurring before the 259th day of gestation (i.e., less than 37 full weeks). RESULTS: Data mining had indicated that maternal vaccination (among other factors) might be related to preterm birth. The following regression analysis showed that, the women who reported being vaccinated shortly before or during gestation had a slightly higher risk of giving preterm birth (O.R. = 1.14; 95% CI 1.04-1.25) as compared to the non-vaccinated group. CONCLUSION: Whether the association between maternal vaccination and the risk for preterm birth found here is causal or not deserves further studies. Data mining, especially with additional refinements, may be a valuable and very efficient tool to screen large databases for relevant information which can be used in clinical and public health research.

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

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.

The effect of roundabout design features on cyclist accident rate.

Roundabouts are known to result in fewer traffic accidents than traditional intersections. However, this is to a lesser degree true for bicycles than for vehicles. In this paper, we aimed at establishing statistical relationships through Poisson regression and logistic regression analyses between yearly rate of cyclist accidents on one hand and roundabout geometry, age and traffic volume (vehicles and cyclists) on the other. We related all roundabout cyclist accidents recorded by the hospital emergency department of the town of Odense, Denmark, through the years 1999-2003 (N=171) to various geometric features, age and traffic volume of all roundabouts on the Danish island of Funen (N=88). Cyclist and vehicle volumes turned out to be significant predictors in most of our models-the higher the volumes, the more accidents. Moreover, potential vehicle speed was a significant predictor, and so was age of the roundabout-older roundabouts related to more accidents and higher accident probability. Excluding 48 single cyclist accidents strengthened the relationship between accidents on one hand and vehicle and cyclist volume and potential vehicle speed on the other. This stresses the significance of speed and traffic volume for traffic accidents with more than one partner involved. The 48 single cyclist accidents were significantly related to the traffic volume of cyclists only. Due to our limited number of observations, the models should be regarded as indicative.

Association between fruit and vegetable consumption and birth weight: a prospective study among 43,585 Danish women.

OBJECTIVE: To examine whether fruit and vegetable consumption in pregnancy is associated with birth weight in a Western population. DESIGN: Prospective cohort study based on telephone interviews, a food frequency questionnaire (FFQ), and extractions of birth characteristics from national health registries. SUBJECTS AND SETTING: The 43,585 Danish women from the Danish National Birth Cohort who had completed the FFQ in mid-pregnancy and on whom information about birth outcome was available. The exposures were frequency of green leafy vegetable (GLV) intake and quantified intake of fruit, fruit and vegetables, and fruit and vegetables and juice. The outcomes were birth weight and z-score for expected birth weight adjusted for sex and gestation week. Information on maternal height, weight, smoking, and other potential confounders was obtained through telephone interviews. RESULTS: Significant associations were found for all exposures to fruit and vegetable intake with birth weight and most with z-score. The strongest association was found for fruit intake in which case birth weight increased by 10.7 g (95% CI 7.3-14.2) per quintile. All associations were stronger among lean women (BMI<20, n = 7,169), whose children's birth weight increased by 14.6 g (95% CI 6.4-22.9) per quintile increase in fruit intake. For GLV the results were more inconclusive. When adjusted for confounders, but not for energy, the association between GLV and birth weight was significant, but the same was not the case for z-score. CONCLUSION: Fruit and vegetable consumption in pregnancy is positively associated with birth weight in well-nourished Danish women, especially among lean women.

Low compliance with recommendations on folic acid use in relation to pregnancy: is there a need for fortification?

OBJECTIVE: As a means to prevent neural tube defects (NTDs), women planning pregnancy in Denmark are recommended to take a dietary supplement of 400 microg folic acid daily during the periconceptional period. We examined compliance with this recommendation in a national survey. DESIGN: Cohort study on pregnant women in Denmark. SETTING: The Danish National Birth Cohort (DNBC). SUBJECTS: From November 2000 to February 2002, 22,000 pregnant women were recruited for DNBC. Use of dietary supplements was recorded at enrollment. Compliance with the recommendation was related to an information campaign that took place during the second half of 2001, and to lifestyle factors provided in a telephone interview by the end of the first trimester of pregnancy. RESULTS: An increase was seen in the proportion of women complying with the recommendation in the study period and this coincided with the information campaign events. However, even at the end of the period, only 22.3% of the women who had planned their pregnancy fully complied with the recommendation. No increase at all was seen in periconceptional folic acid use among women with unplanned pregnancies. Young age, low education and smoking were identified as factors that determined non-compliance. CONCLUSIONS: Alternative and more effective strategies are needed if the Danish population is to benefit fully from the knowledge that folic acid prevents NTDs. Future strategies should not only target vulnerable groups, such as the less educated and the young, but also women who get pregnant without planning this. The only possible way to reach the last group may be through fortification of foods with folic acid.