It is well known that very low birth weight and preterm birth are risk indicators for delayed child development. It is the purpose of this study to estimate the association between birth weight, placenta weight, and gestational age in consecutive pregnancies which survived till after 28th week of gestation. The association between fecundity and child development is also studied. Data stem from pregnant women in a well defined regional area in Denmark (Odense) who participated in a concerted action on moderate alcohol consumption in pregnancy (EuroMac). All pregnant women with an alcohol consumption of 5 drinks or more per week or more in the first trimester were selected for the study in 1988 to 1989. A one to one match of pregnant woman was selected among the remaining pregnant woman based upon expected time of delivery and age. Altogether 326 women were selected for the study and the two groups are combined since alcohol intake in the measured dose range had no association with child development. The newborn went through two psychological tests at 18 month (the Bayley test) and again at 42 months of age (the Griffiths' test). Two hundred fiftynine pairs of mothers and children participated in all parts of data collection. Birth weight and gestational age was associated with the psychological scoring in the test performed at 18 and 42 months of age, especially the psychomotor index. Especially newborns with low birth weight and high placenta weight had low score values on mental development indices. No association was seen between a measure of fecundity (waiting time to pregnancy) and reduced child development.
Impaired fetal growth is associated with increased susceptibility to several chronic diseases. We studied the association between birth weight, indicators of disproportional fetal growth, and impaired visual acuity and hearing in 4,300 conscripts from a well-defined region in Denmark from August 1, 1993, to July 31, 1994. From the standard health examination for conscripts, we obtained data on sight based on the Snellen's chart and data on hearing acuity based on audiometry. By means of record linkage, we obtained data on outcomes for the conscripts at birth from the Medical Birth Registry. From this registry, we have data on birth weight, gestational age, and birth length that were recorded from existing computerized registers based on the records of midwives. A birth weight of less than 3,000 gm and a body mass index at birth of less than 3.4 were associated with reduced visual acuity and impaired hearing. The results could be due to fetal brain programming or due to confounding, by early birth trauma or other factors.
STUDY OBJECTIVE--The aim was to investigate whether specific types of work or exposures among pharmacy assistants were correlated with changes in birth weight or gestational age. DESIGN--The study was a nationwide historical cohort with open entry of all female members of the union of pharmacy assistants during 1979 to 1984. PARTICIPANTS--The cohort comprised 4939 pharmacy assistants under 40 years of age. The questionnaire was answered by 93%. MEASUREMENTS AND MAIN RESULTS--Information on birth weight and gestational age was obtained by linkage to the national birth register. Exposure information on type of work and exposure to pharmaceutical and chemical products during pregnancy was self reported. Only small and non-significant differences in birth weight and gestational age were found between the compared groups. Mean birth weight was 50 g above the national mean and gestational age was longer (p less than 0.0005). CONCLUSIONS--Compared to the Danish population, children of pharmacy assistants are at low risk for experiencing low birth weight and preterm birth. Social status and less smoking during pregnancy among pharmacy assistants might explain the slightly greater mean birthweight and gestational age in this sector of the population.
To examine the timing of reaching developmental milestones in children born post-term.
The Danish National Birth Cohort: children born between 1997 and 2003.
Data were obtained from a cohort of 92 892 pregnancies participating in the first pregnancy interview. All singletons born in gestational weeks 39-45 were identified. The study was then restricted to children who participated in an interview at the age of approximately 18 months and had information on at least one developmental milestone. We excluded children of mothers with chronic diseases from the final analysis. The remaining study population constituted of 43 915 singletons (27 503 born at term; 16 412 born post-term).
Logistic regression was used to calculate odds ratios of late achievement of these developmental milestones, adjusted for potential confounding factors.
Achieving developmental milestones at the time of interview or at a certain age.
More children born post-term achieved the assessed developmental milestones compared with children born at term (39-40 weeks). A test for trend for gestational ages 39, 40, and 41 weeks also showed a positive trend at achieving developmental milestones with gestational age at birth in nine out of 14 milestone items.
Children born post-term appear to reach the main developmental milestones at an earlier age than children born at term. The association could also result from bias related to a longer time between conception and interviewing, misclassification of end points, or selection bias.
This study investigates whether consumption of fish during pregnancy may prolong gestation or increase fetal growth. From 1984 to 1987, 11,980 pregnant Danish women filled out a questionnaire while they were in the 36th week of gestation; this was 83% of all such women living in two geographically defined areas. The women were divided into four strata dependent on having consumed a fish meal 0, 1-2, 3-4, or 5+ times during the previous month. In non-smokers, a one level increase in fish consumption was, after adjusting for 19 other variables in a multiple regression model, found to be associated with an increase of 11 g in placental weight, 0.08 cm in head circumference and 16 g in birthweight (95% confidence intervals (CI) 5 to 17 g (p = 0.0002), 0.02 to 0.14 cm (p = 0.02), and -2 to 34 g (p = 0.09), respectively); no associations with birth length or gestational age could be detected (95% Cl-0.07 to 0.11 cm (p = 0.7) and -0.82 to 0.05 days (p = 0.2), respectively, per level change in fish consumption). None of the associations seen in non-smokers were seen in smokers. We postulate that the associations seen in non-smokers could be due to marine n-3 fatty acids improving placental blood flow by increasing the ratio of prostacyclins to thromboxane. Smoking may possibly interfere with this mechanism via nicotine's inhibitory effect on platelet thromboxane production.
We studied the association between acetaminophen exposure during pregnancy and the prevalence of congenital abnormalities and fetal growth. Our study included 123 women who had received a prescription of acetaminophen during pregnancy and/or 30 days before conception and 13,329 controls who did not receive any prescription at all. We found more malformations among those who received a prescription with an odds ratio of 2.3 (95% CI 1.0-5.4), but the type of malformations did not indicate a causal link. When restricting the study to first time pregnancies, we identified 58 women who received a prescription of acetaminophen during pregnancy and 30 days before conception and 7472 controls. We found no excess risk of malformation [OR = 0.7 (95% CI 0.1-5.5)], and no evidence that acetaminophen should influence fetal growth.
Developmental Disabilities Branch, Division of Birth Defects, Child Development, and Disability and Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, GA 30341, USA. PCT9@CDC.GOV
Fetal and neonatal mortality and morbidity rates are strongly associated with gestational age for delivery: the risk for poor outcome increases as gestational age decreases. Attempts to predict preterm delivery (PTD, spontaneous delivery before 37 weeks' gestation) have been largely unsuccessful, and rates of PTD have not improved in recent decades. More recently, the reported associations between infections in pregnancy and PTD suggest preventive initiatives that could be taken. The overall objective of the current study is to assess whether specific markers of infection (primarily interleukin (IL) 1beta, tumour necrosis factor (TNF) alpha, IL-6, and IL-10) obtained from maternal blood during pregnancy, alone or in combination with other risk factors for PTD, permit identification of women at risk for spontaneous PTD. To achieve this objective, data are obtained from two Danish prospective cohort studies involving serial collection of maternal blood samples, newborn cord blood samples, and relevant confounders and other risk factors for PTD. The first study consists of a completed Danish regional cohort of 3000 pregnant women enrolled in a study of microbiological causes of PTD, upon which a nested case-control study of PTD in 84 cases and 400 controls has been performed. The second study is a nested case-control study of 675 PTD cases (equally divided into three gestational age categories of 24-29 weeks' gestation, 30-33 weeks' gestation, and 34-36 weeks' gestation) and 675 controls drawn from the ongoing Danish National Birth Cohort study of 100 000 pregnant women enrolled during 1997-2001. The second study will provide the opportunity to refine and retest hypotheses from the first study, as well as to explore new hypotheses. Our preliminary work suggests that a single predictive marker effectively accounting for a large proportion of PTD is unlikely to be found. Rather, a search for multiple markers indicative of the multifactorial aetiology of PTD is likely to be more successful. Knowledge gained from the proposed studies will be implemented in a third, clinical intervention study against PTD. The first phase of the clinical intervention study will be to establish a risk-assessment model based on the "best" combination of biological/biochemical measures and other factors associated with PTD in order to identify pregnant women at very high risk of PTD. The second phase will be to apply an intervention model of tailored obstetric care to the very high-risk pregnant women for PTD identified in phase one. The intervention will be carried out against each specific risk factor associated with PTD identified for the individual. The aim is to reduce the risk for PTD attributed to the combination of risk factors included in the clinical intervention study.
We evaluated the association between indicators of fetal growth and hospitalization with infectious disease during childhood in a cohort of 10,400 newborns. The cohort was based on children born to mothers who at about 36 weeks of gestation attended the midwife centres in Odense and Aalborg, Denmark for a routine examination. Women were recruited to the study from April 1984 to April 1987. After linkage with the National Hospital Registry, the first hospitalization with infectious disease from 6 months up to 12 years of age was identified. The cumulative incidence of hospitalization with infectious disease during follow-up was 18.9%. Preterm birth was associated with an increased risk of being hospitalized with infections during childhood (incidence rate ratio: 1.67, 95% CI: 1.33-2.10); low birth weight had a similar association, but only in preterm birth. Reduced birth length related to the head was correlated with an increased risk of hospitalization with infections. The effect of gestational age was mainly seen in the period close to the time of birth, but the children who were short at birth appeared to remain at increased risk throughout the age interval under analysis. In conclusion, the study suggests that preterm birth was the main factor underlying the association between low birth weight and the increased risk of hospitalization with infectious disease during childhood. However, it could not explain the increased risk in children who were short at birth.