We asked whether breastfeeding reduces the risk of epilepsy in childhood.
We included 69 750 singletons born between September 1997 and June 2003 in the Danish National Birth Cohort and observed them to August 2008. Information on breastfeeding was reported by mothers in two computer-assisted telephone interviews at 6 and 18 months after birth. Information on epilepsy (inpatients and outpatients) was retrieved from the Danish National Hospital Register. Cox proportional hazards regression models were used to estimate incidence rate ratios and 95% CIs.
Breastfeeding was associated with a decreased risk of epilepsy, with a dose-response like pattern. For example, children breastfed for 3 to 5, 6 to 8, 9 to 12, and = 13 months had a 26%, 39%, 50%, and 59% lower risk of epilepsy after the first year of life, respectively, compared with children who were breastfed for
The authors conducted a cohort study within the Danish National Birth Cohort to determine whether coffee consumption during pregnancy is associated with late fetal death (spontaneous abortion and stillbirth). A total of 88,482 pregnant women recruited from March 1996 to November 2002 participated in a comprehensive interview on coffee consumption and potentially confounding factors in pregnancy. Information on pregnancy outcome was obtained from the National Hospital Discharge Register and medical records. The authors detected 1,102 fetal deaths. High levels of coffee consumption were associated with an increased risk of fetal death. Relative to nonconsumers of coffee, the adjusted hazard ratios for fetal death associated with coffee consumption of 1/2-3, 4-7, and > or =8 cups of coffee per day were 1.03 (95% confidence interval (CI): 0.89, 1.19), 1.33 (95% CI: 1.08, 1.63), and 1.59 (95% CI: 1.19, 2.13), respectively. Reverse causation due to unrecognized fetal demise may explain the association between coffee intake and risk of fetal death prior to 20 completed weeks' gestation but not the association with fetal loss following 20 completed weeks' gestation. Consumption of coffee during pregnancy was associated with a higher risk of fetal death, especially losses occurring after 20 completed weeks of gestation.
The objective of the study was to investigate the association between maternal self-reported infections, fever, and smoking in the prenatal period and the subsequent risk for congenital cerebral palsy (CP).
We included the 81,066 mothers of singletons born between 1996 and 2003 who participated in the Danish National Birth Cohort. Children were followed up through December 2008. Information on maternal infections, fever, smoking, and other demographic and lifestyle factors during pregnancy were reported by mothers in computer-assisted telephone interviews in early and midgestation. We identified 139 CP cases including 121 cases of spastic CP (sCP) as confirmed by the Danish National Cerebral Palsy Register. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).
Self-reported vaginal infections were associated with an increased risk of CP and sCP (aHR, 1.52; 95% CI, 1.04-2.24; and aHR, 1.73; 95% CI, 1.16-2.60, respectively) and particularly untreated vaginal infections were associated with an increased risk of sCP (aHR, 1.95; 95% CI, 1.16-3.26). Fever was associated with the risk of CP (aHR, 1.53; 95% CI, 1.06-2.21). Smoking 10 or more cigarettes per day during pregnancy was also associated with sCP (aHR, 1.80; 95% CI, 1.10-2.94). There was a modest excess in risk for children exposed to both heavy smoking and vaginal infections. No other self-reported infections were significantly associated with CP.
Self-reported vaginal infections, fever, and smoking 10 or more cigarettes per day during pregnancy were associated with a higher risk of overall CP and/or sCP.
Humans are exposed to perfluorinated alkyl acids (PFAAs) from food, drinking water, air, dust, and consumer products. PFAAs are persistent and bio-accumulative. In the present study, we aimed to establish how the serum levels of PFAAs differ according to age, pre-pregnancy body mass index (BMI), previous miscarriages, educational level, country of birth, smoking, and alcohol intake. We included 1438 Danish pregnant nulliparous women from the Aarhus Birth Cohort. The women gave a blood serum sample between week 11 and 13 of pregnancy. Sixteen PFAAs were extracted from serum using solid phase extraction and analyzed by liquid chromatography/tandem mass spectrometry. Multivariable linear regression analysis was used to determine the associations between individual characteristics of the women and their levels of seven PFAAs that were detected in at least 50% of the samples. The total concentration of the PFAAs (?PFAA) was higher in older women. On average, normal weight women had a higher ?PFAA level than underweight, overweight, and obese women. Higher levels were also observed for women without previous miscarriages, women with a high educational level, women born in Denmark (as opposed to women born elsewhere but currently living in Denmark), non-smokers, and women who consumed alcohol before or during pregnancy. These associations were similar for all the studied PFAAs, although the levels of perfluoroundecanoic acid varied more across the categories of age, BMI, education, smoking, and alcohol consumption than any other PFAAs measured.
To investigate the association between proportionality of fetal and placental growth measured at birth and the risk for congenital cerebral palsy (CP).
We identified all live-born singletons born in Denmark between 1995 and 2003 and followed them from 1 year of age until December 31st, 2008. Information on four indices of fetal growth: ponderal index, head circumference/ abdominal circumference ratio, cephalization index and birth weight/ placenta weight ratio was collected. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). All measurements were evaluated as gestational age and sex specific z-scores and in z-score percentile groups, adjusted for potential confounders, and stratified on gestational age groups (
BACKGROUND: There has been an apparent decline in sperm density during the last 5 decades in Denmark, a country in which women have among the highest rates of smoking in Europe. We examined semen quality and sex hormones in men in relation to their mothers' tobacco smoking during pregnancy. METHODS: Male participants were selected from the population-based Danish Twin Registry and the Danish Civil Registration System as part of a study on hereditary and environmental determinants of semen quality. From November 1999 to May 2000 we collected one fresh semen and blood sample from each of 316 men. Data on prenatal tobacco exposure were obtained for 265 of these men from a questionnaire filled in by their mothers. RESULTS: Adjusting for age, current smoking status and other factors, sperm density was 48% lower(95% confidence interval = -69% to -11) among sons of mothers who smoked more than 10 cigarettes per day during pregnancy. Total sperm counts and levels of inhibin-B were also reduced among this group, whereas follicular stimulating hormone levels were somewhat higher (16% increase; 95% confidence interval = -13% to 54%). These effects were not seen in the lower smoking category (1-10 cigarettes per day). CONCLUSIONS: High levels of smoking (> 10 cigarettes per day) during pregnancy may be a partial explanation for the apparent secular decline and the geographic differences in sperm counts.
If interviewers' personal habits or attitudes influence respondents' answers to given questions, this may lead to bias, which should be taken into consideration when analyzing data. The authors examined a potential interviewer effect in a study of pregnant women in which exposure data were obtained through computer-assisted telephone interviews. The authors compared interviewer characteristics for 34 interviewers with the responses they obtained in 12,910 interviews carried out for the Danish National Birth Cohort Study. Response data on smoking and alcohol consumption in the first trimester of pregnancy were collected during the time period October 1, 1997-February 1, 1999. Overall, the authors found little evidence to suggest that interviewers' personal habits or attitudes toward smoking and alcohol consumption during pregnancy had consequences for the responses they obtained; neither did the interviewers' education, age, or parity correlate with the answers they obtained. In these data gathered through computer-assisted telephone interviews, interviewer effects arising from variations in interviewers' health beliefs and personal habits were found to be negligible. Thorough training of the interviewers and continuous supervision may have contributed to this finding.
Preterm and growth restricted infants may have developmental delays and deviations from normal organ function related to the gastrointestinal tract and the central nervous system. Since both organ systems are hypothesised to be involved in the pathogenesis of infantile colic, a condition characterised by excessive crying during the first months of life, impaired fetal growth and preterm birth may be risk factors for infantile colic.
A total of 62,761 liveborn singletons from the Danish National Birth Cohort (1996 to 2002) were studied. Infantile colic was defined according to Wessel's modified criteria based on maternal interview conducted at 6 months post-partum.
A total of 2605 (4.2%) infants were born preterm, 54,441 (86.7%) at term, and 5715 (9.1%) post-term. A total of 4964 (7.9%) infants fulfilled Wessel's modified criteria for infantile colic. The risk for infantile colic increased with decreasing gestational age after adjustment for covariates. The highest odds [odds ratio (95% confidence interval)] was observed for infants born before 32 completed gestational weeks (1.5 [95% CI 1.0, 2.2], reference: 40 gestational weeks). Small for gestational age infants (birthweight below 10th percentile) had an increased odds of infantile colic (1.2 [95% CI 1.1, 1.3]) in all gestational age groups.
We observed an increased risk of infantile colic in preterm and small for gestational age infants in a large cohort. Our results suggest that the aetiology of infantile colic may be found in the prenatal, perinatal, and neonatal period.
BACKGROUND: Pre-eclampsia shares a number of risk factors with cardiovascular disease (CVD). Women with recurrent pre-eclampsia or pre-eclampsia early in pregnancy reportedly have an increased long-term risk of CVD. Short stature is a risk factor for CVD but has rarely been examined in relation to pre-eclampsia. METHODS: We used data from 59 968 singleton live births in the Danish National Birth Cohort born between 1998 and 2001 to assess risk of severe pre-eclampsia/eclampsia (296 cases) in relation to self-reported height. We examined the association in multiple logistic regressions stratified by parity. RESULTS: Among primiparas there was a weak association (compared with women 172 cm had on OR of 0.79, 95% CI: 0.55, 1.14). Among multiparas, the tallest women had an adjusted OR of 0.42 (95% CI: 0.20, 0.87) of developing severe pre-eclampsia compared with women
Smoking is a well-established risk factor for fetal growth restriction and other adverse pregnancy outcomes, and nicotine may be one of the chemical compounds that drive these associations. Nicotine replacement therapy (NRT) is a smoking cessation aid, which can facilitate smoking cessation. It is, however, unknown whether NRT used during pregnancy impairs fetal growth. The aim of this study was to estimate the association between the use of NRT during pregnancy and offspring birthweight. The study population consisted of 72 761 women enrolled in the Danish National Birth Cohort between 1996 and 2002. Information on NRT and potential confounders was obtained from two computer-assisted telephone interviews conducted in the second and third trimesters, respectively. Multiple linear regression in a multilevel model was used to estimate the association between NRT use and birthweight adjusted for gestational age and potential confounders. The adjusted analyses showed no significant association between the duration of NRT use and birthweight (b = 0.25 g per week of NRT use [95% CI -2.31, 2.81]) and neither was the type of NRT product (patch, gum, inhaler) associated with reduced birthweight. However, simultaneous use of more than one NRT product was associated with reduced birthweight (b = -10.73 g per week of NRT use [95% CI -26.51, 5.05]), although the association was not statistically significant. The results of this study suggest that maternal use of NRT in pregnancy does not seriously affect birthweight, but there could be a negative effect on birthweight associated with simultaneous use of more than one type of NRT product.