Geir Jacobsen

Birthweight and mortality in adulthood: a systematic review and meta-analysis

BACKGROUND Small birth size may be associated with increased risk of cardiovascular diseases (CVD), whereas large birth size may predict increased risk of obesity and some cancers. The net effect of birth size on long-term mortality has only been assessed in individual studies, with conflicting results. METHODS The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer. The studies were systematically reviewed and those reporting hazard ratios (HRs) and 95% confidence intervals (95% CIs) per kilogram (kg) increase in birthweight were included in generic inverse variance meta-analyses. RESULTS For all-cause mortality, 36,834 deaths were included and the results showed a 6% lower risk (adjusted HR = 0.94, 95% CI: 0.92-0.97) per kg higher birthweight for men and women combined. For cardiovascular mortality, the corresponding inverse association was stronger (HR = 0.88, 95% CI: 0.85-0.91). For cancer mortality, HR per kg higher birthweight was 1.13 (95% CI: 1.07-1.19) for men and 1.04 (95% CI: 0.98-1.10) for women (P(interaction) = 0.03). Residual confounding could not be eliminated, but is unlikely to account for the main findings. CONCLUSION These results show an inverse but moderate association of birthweight with adult mortality from all-causes and a stronger inverse association with cardiovascular mortality. For men, higher birthweight was strongly associated with increased risk of cancer deaths. The findings suggest that birthweight can be a useful indicator of processes that influence long-term health.

Pre- and post-natal growth in children of women who smoked in pregnancy.

Pre- and post-natal growth was studied from week 17 of pregnancy until 5 years of age in children of women who reported daily smoking at the time of conception, and compared to the growth in children of non-smokers. Fetal abdominal diameter, femur length and biparietal diameter were measured in weeks 17 and 37 of pregnancy, and weight, height and head circumference were measured at birth, and at 6, 13 and 60 months of age in 185 children of smokers and 345 children of non-smokers. Cross sectional data at birth showed that infants of smokers had lower weight and length, but similar ponderal index as infants of non-smokers and this may suggest a symmetrical growth retardation. Longitudinal growth curves indicated that the growth retardation took place in the second half of pregnancy. During the first 5 years of life, children of smokers had complete catch-up growth in weight, a partial catch-up in height, and no catch-up growth in head circumference. At 5 years, children of smokers had a higher ponderal index and skinfold thickness, suggesting that these children, on average, were more obese than children of non-smokers.

Breast feeding and cognitive development at age 1 and 5 years

AIM To examine whether duration of breast feeding has any effect on a childs cognitive or motor development in a population with favourable environmental conditions and a high prevalence of breast feeding. METHODS In 345 Scandinavian children, data on breast feeding were prospectively recorded during the first year of life, and neuromotor development was assessed at 1 and 5 years of age. Main outcome measures were Bayleys Scales of Infant Development at age 13 months (Mental Index, MDI; Psychomotor Index, PDI), Wechsler Preschool and Primary Scales of Intelligence (WPPSI-R), and Peabody Developmental Scales at age 5. RESULTS Children breast fed for less than 3 months had an increased risk, compared to children breast fed for at least 6 months, of a test score below the median value of MDI at 13 months and of WPPSI-R at 5 years. Maternal age, maternal intelligence (Raven score), maternal education, and smoking in pregnancy were significant confounders, but the increased risk of lower MDI and total IQ scores persisted after adjustment for each of these factors. We found no clear association between duration of breast feeding and motor development at 13 months or 5 years of age. CONCLUSION Our data suggest that a longer duration of breast feeding benefits cognitive development.

Randomised controlled trial of ultrasonographic screening in pregnancy.

510 of 1009 pregnant women in the Trondheim area (Norway) were randomly selected for ultrasound examination at the 19th and 32nd weeks of pregnancy in addition to routine antenatal care. Among the screened women, twins were diagnosed earlier and there were slightly fewer post-term inductions (2.8% versus 4.0%) and fewer low-weight births (2.2% versus 3.6% less than 2500 g), but none of these differences was statistically significant. There were no differences in the condition of the newborn. Small-for-gestational-age births were more often diagnosed antenatally in the screened group and the mothers received more active treatment. During pregnancy, screened women were admitted to hospital more often than unscreened women (15.5% versus 9.2%). The study revealed no adverse short-term biological effects from ultrasound. The cost of the screening programme, including associated costs such as extra hospital admissions, was about US

Maternal pregnancy estriol levels in relation to anamnestic and fetal anthropometric data.

250 per pregnancy.

Pre-pregnancy risk factors of small-for-gestational age births among parous women in Scandinavia

In epidemiologic studies of perinatal exposures, birth weight has been proposed as a proxy variable for intrauterine estrogen exposure. To assess the validity of this assumption, we performed analyses of the association between estriol levels in 188 women in the 17th, 25th, 33rd, and 37th weeks of pregnancy and the birth weights of their infants. We found a general increase in mean cumulative estriol dose with increasing birth weight category throughout pregnancy. In late pregnancy, mean pregnancy estriol level of mothers of infants in the highest birth weight category (>4,500 gm) was twice as high as that of mothers of infants in the lowest category (<2,500 gm), 775 nmol/liter and 392 nmol/liter, respectively. Smoking lowered the maternal estriol levels by 20% or more throughout pregnancy. With smoking and birth weight included in a regression analysis, maternal age, placental weight, and infant ponderal index did not add any explanatory power to the model. Our data suggest that, on an aggregate level, birth weight can be used as a proxy variable of intrauterine estriol exposure.

Maternal recall of breastfeeding duration twenty years after delivery

To study the etiology and consequences of intrauterine growth retardation (IUGR), a prospective study was organized by the National Institute of Child Health and Human Development, NIH, with the Universities of Trondheim and Bergen in Norway, Uppsala in Sweden, and Alabama in the United States. This paper reports on the Scandinavian portion of the study. 6,354 women were referred to the study and 5,722 women, who were expecting their second or third child between January 1986 and March 1988, were eligible and made their first appointment for the study. Of these, 1,945 women and their births were selected for follow‐up at four prenatal visits, delivery, and during the first year of life. This report analyzes the relative impact of various maternal pre‐pregnancy risk factors associated with SGA birth. For example, mothers who smoked cigarettes around the time of conception, but who had none of the other major risk factors, nearly doubled their risk of SGA birth. A previous low birth weight (LBW) delivery increased the risk nearly two and a half times among non‐smokers. If a mother both smoked and had a previous LBW, the relative risk rose to nearly five and a half. Low maternal pre‐pregnancy weight (> 50 kg) increased the risk of SGA birth almost twofold among non‐smokers, while low pre‐pregnancy weight and smoking together increased the risk of SGA birth fourfold. A low weight mother who smoked and also had a previous LBW delivery, had a risk of SGA birth that was nearly six times that of a mother without those characteristics.

Cognitive development of term small for gestational age children at five years of age

BackgroundStudies on the health benefits from breastfeeding often rely on maternal recall of breastfeeding. Although short-term maternal recall has been found to be quite accurate, less is known about long-term accuracy. The objective of this study was to assess the accuracy of long-term maternal recall of breastfeeding duration.MethodsIn a prospective study of pregnancy and birth outcome, detailed information on breastfeeding during the child’s first year of life was collected from a cohort of Norwegian women who gave birth in 1986–88. Among 374 of the participants, data on breastfeeding initiation and duration were compared to recalled data obtained from mailed questionnaires some 20 years later. Intraclass correlation coefficient (ICC), Bland-Altman plot, and Kappa statistics were used to assess the agreement between the two sources of data. Logistic regression was used to assess predictors of misreporting breastfeeding duration by more than one month.ResultsRecorded and recalled breastfeeding duration were strongly correlated (ICC=0.82, p < 0.001). Nearly two thirds of women recalled their breastfeeding to within one month. Recall data showed a modest median overestimation of about 2 weeks. There were no apparent systematic discrepancies between the two sources of information, but recall error was predicted by the age when infants were introduced to another kind of milk. Across categories of breastfeeding, the overall weighted Kappa statistic showed an almost perfect agreement (κ = 0.85, 95% confidence interval [CI] 0.82 – 0.88).ConclusionBreastfeeding duration was recalled quite accurately 20 years after mothers gave birth in a population where breastfeeding is common and its duration long.

Increased levels of cytokines and cytokine activity modifiers in normal pregnancy

AIM To assess the relative significance for cognitive development of small for gestational age, parental demographic factors, and factors related to the child rearing environment. METHODS IQ of a population based cohort of 338 term infants who were small for gestational age (SGA) and without major handicap, and a random control sample of 335 appropriate for gestational age (AGA) infants were compared at 5 years of age. RESULTS The mean non-verbal IQ was four points lower, while the mean verbal IQ was three points lower for the children in the SGA group. The results were not confounded by parental demographic or child rearing factors. However, parental factors, including maternal non-verbal problem solving abilities, and child rearing style, accounted for 20% of the variance in non-verbal IQ, while SGA versus AGA status accounted for only 2%. The comparable numbers for verbal IQ were 30 and 1%. Furthermore, we found no evidence that the cognitive development of SGA children was more sensitive to a non-optimal child rearing environment than that of AGA children. Maternal smoking at conception was associated with a reduction in mean IQ comparable to that found for SGA status, and this effect was the same for SGA and AGA children. The cognitive function of asymmetric SGA was comparable to that of symmetric SGA children. CONCLUSIONS Our findings indicate that child cognitive development is strongly associated with parental factors, but only marginally associated with intrauterine growth retardation.

Physical abuse and low birthweight: a case‐control study

Accumulating evidence suggests that cytokines are major participants in human reproduction. Cytokines may have beneficial or negative influence on pregnancy outcome, depending on the cytokine level present. Thus, successful reproduction appears to depend on a tight regulation of cytokine activities. The present study raised the question whether normal pregnancy is associated with an activation of native cytokine buffer mechanisms. Soluble interleukin 6 receptors (IL-6Rs) and soluble interleukin 1 receptor antagonists (IL-1RAs) may modify the activity of IL-6 and IL-1, respectively. The production of soluble IL-6R and IL-1RA in pregnancy was studied by assessing the IL-6R and IL-1RA concentrations in serum samples from healthy pregnant women at different gestational ages. At delivery, both maternal and umbilical blood was obtained. Concentrations of IL-6 and IL-1 in the samples were determined to study the influence of cytokines on the activity level of the corresponding buffer mechanism. Serum levels of both IL-6R and IL-1RA were increased in pregnant women, as were levels of IL-6 and IL-1. Cytokine levels did not demonstrate a significant correlation with the concentration of the corresponding activity modifier. IL-1RA and IL-6 increased with gestational age and with labor activity. A significant correlation was observed between the levels of IL-6 and IL-1RA.