Neonatal cranial ultrasound abnormalities in low birth weight infants: relation to cognitive outcomes at six years of age.

OBJECTIVE: To assess the independent relation of neonatal cranial ultrasound (US) abnormalities in low birth weight (LBW) infants to cognitive outcomes at 6 years of age. DESIGN: Prospective cohort study. SAMPLE AND METHODS: Six-year follow-up data were obtained on a regional birth cohort of LBW infants (< 2 kg) systematically screened as neonates with serial US. US abnormalities were dichotomized into isolated germinal matrix/intraventricular hemorrhage (GM/IVH) and parenchymal lesions/ventricular enlargement (PL/VE). Global cognitive outcomes (mental retardation, borderline intelligence, and normal intelligence) and selected specific cognitive abilities were assessed at 6 years of age with standardized instruments. Multivariate techniques were used to assess the effects of US independent of maternal social disadvantage at birth and other perinatal and neonatal risk factors. RESULTS: The sample as a whole had a significantly elevated rate of mental retardation (MR; 5%), almost all moderate to profound in severity. PL/VE was independently related to MR (odds ratio [OR], 65.8; confidence interval [CI], 19.1 to 22.4) and borderline intelligence (OR, 3.7; CI, 1.3 to 10.8); isolated GM/IVH was more modestly related to MR (OR, 4.6; CI, 1.2 to 18.6) but not related to borderline intelligence. Approximately half of the cases of MR were attributable to PL/VE independent of other factors. Of non-US factors, the number of days receiving mechanical ventilation increased the risk for MR. Maternal social disadvantage increased the risk for borderline intelligence but not MR. Among children of normal intelligence, those with PL/VE, but not isolated GM/IVH, performed more poorly than those without US abnormalities on tests of visual perceptual organization but not on tests of language, memory, or quantitative skills. CONCLUSION: Prevention of white matter injury would substantially improve cognitive outcomes for LBW infants.

Vision outcome at age 2 years in a low birth weight population.

We assess the prevalence of vision problems in a cohort of low birth weight infants at age 2 years and the relationship of these problems to neonatal brain injury. Data on prenatal and neonatal history and brain injury status were prospectively collected on 721 children weighing 500-2,000 gm at birth enrolled in a multi-center, population-based longitudinal study. Visual acuity was evaluated using the Teller Acuity Card Procedure. Abnormalities of the eye were assessed by a specially trained pediatric nurse practitioner. Failure of the acuity screen occurred in 62 of 699 tested (8.9%). Multiple logistic regression analysis revealed that the only significant independent predictors of failure included presence of disabling cerebral palsy (DCP) (odds ratio [OR] = 14.8) or nondisabling cerebral palsy (NDCP) (OR = 4.0) and Apgar score of less than 5 at 5 minutes (OR = 2.4). Parenchymal brain injury (PEL) was of borderline significance. Strabismus was present in 123 of 702 children (17.5%). Multiple logistic regression analysis disclosed that the joint predictors of strabismus were presence of DCP (OR = 7.2) and length of hospital stay (OR = 1.6). We conclude that low birth weight infants with parenchymal brain lesions leading to cerebral palsy are at particular risk for vision problems early in life and should be carefully evaluated.

Fish consumption and other characteristics of reproductive-aged Michigan anglers--a potential population for studying the effects of consumption of Great Lakes fish on reproductive health.

There has been considerable interest in the benefits and risks of eating Great Lakes fish, particularly with regard to reproductive health. We report the results of a survey conducted from 1993-1995 among Michigan anglers. The survey was designed to identify a reproductive-aged cohort of persons who consume high or low levels of Great Lakes fish in order to study the impact of polyhalogenated biphenyl (PHB) compounds and other toxins on human reproduction outcomes. Using fishing license data obtained from the Michigan Department of Natural Resources, we identified anglers of early reproductive age (18-34 years) in ten Michigan counties. The screening survey ascertained demographic, behavioral, fish consumption, and reproductive history information on anglers and their partners. Over 4,000 angler households were contacted. One thousand nine hundred fifty questionnaires were returned from 1,168 households. The median age of respondents was 30 years; 58% were male and 64% reported being married. Slightly more than one-half the respondents had attended or graduated from college, and less than 10% had not completed high school. In the past year, most respondents (46%) reported having eaten sport-caught fish 1-12 times, while 20% reported having eaten no sport-caught fish; 20% had consumed 13-24 meals. More sport-caught fish was consumed in the spring and summer than in the fall and winter, and males reported eating more fish than females. About 43% of our respondents reported that they intend to have one or more children in the next five years. Of these respondents, 287 couples had no identified impairments to reproduction and therefore would be eligible to participate in the future reproductive study.

The problem of low birth weight.

Low birth weight is a major public health problem in the United States, contributing substantially both to infant mortality and to childhood handicap. The principal determinant of low birth weight in the United States is preterm delivery, a phenomenon of largely unknown etiology. Preterm delivery is more common in the United States than in many other industrialized nations, and is the factor most responsible for the relatively high infant mortality rate in the United States. Within the United States, Asian populations experience the lowest preterm delivery rates, while Hispanic and Native American populations experience slightly higher preterm delivery rates than the white population. African Americans, however, have much higher rates of preterm delivery than any of the other major ethnic groups. Poverty is strongly and consistently associated with low birth weight, but the precise social and environmental conditions that produce preterm delivery have not been elucidated. Although it is popular to link illicit drug use to low birth weight, a high low birth weight rate was characteristic of the United States for decades before the cocaine epidemic of the 1980s. Neither the low birth rate nor the preterm delivery rate has improved in the United States in the past quarter century. Most efforts to prevent prematurity or low birth weight, when carefully evaluated, have not proven effective. A major goal of biomedical research ought to be better understanding of the causes of this important public health problem.

Time-trends in necropsy prevalence and birth prevalence of lung hypoplasia.

Congenital lung hypoplasia (LH) has been identified with increasing frequency in perinatal and neonatal necropsy reviews. The available prevalence figures have been derived using various diagnostic criteria in different populations and at various times. We therefore reviewed our experience in 15 years of consecutive early neonatal necropsies using one constant set of diagnostic criteria for LH and looked for a time-trend. We determined the necropsy prevalence (no. of cases of LH/no. of necropsies) and the birth prevalence (no. of cases of LH documented at necropsy per 1000 livebirths for inborn patients, and per 1000 referrals for outborn patients) between 1971 and 1985. We then divided this 15-year period into five consecutive 3-year periods to determine if a time-trend was discernible. Whereas early neonatal mortality for neonatal intensive care unit (NICU) admissions progressively decreased from 11.4% to 4.0% between the first and the last 3-year periods, the number of cases of LH per 3-year period did not vary appreciably. As a result, the prevalence of LH at necropsy showed a slight upward trend with time. The overall prevalence was 18%; it was 13% during the first and 23% during the last 3-year period. We found no time-trend in birth or referral prevalence for this lesion, which averaged 1.1 per 1000 livebirths and 9.8 per 1000 referrals. We conclude that lung hypoplasia appears to be emerging as an increasingly prevalent necropsy finding as a result of a shift in proportionate mortality, with the number of patients dying of other causes (denominator) decreasing, and the number of patients dying with lung hypoplasia remaining constant.