Effect of continuing or stopping smoking during pregnancy on infant birth weight, crown-heel length, head circumference, ponderal index, and brain:body weight ratio.

The objective of this study was to determine whether stopping smoking between the first prenatal care visit and the 32nd week of pregnancy affects the smoking-associated changes in five infant anthropometric indices. The study population consisted of 15,185 births in the Swedish Medical Birth Register from 1991 and 1992. The associations between birth weight, crown-heel length, head circumference, ponderal index, brain:body weight ratio, maternal smoking status at the first prenatal care visit and at 32 weeks' gestation, and other maternal and infant characteristics were assessed using multivariate linear regression. The infants of 946 women who stopped smoking before week 32 of pregnancy were statistically indistinguishable from the 9,802 infants of nondaily smokers in terms of birth weight, head circumference, and brain:body weight ratio, but they retained a significant deficit in crown-heel length of 0.23 cm (standard error, 0.08) and a significant elevation in ponderal index of 0.027 (standard error, 0.009). In this study, stopping smoking between the first prenatal care visit and week 32 of pregnancy prevented smoking-associated deficits in infant birth weight, head circumference, and brain:body weight ratio, but did not completely prevent deficits in crown-heel length in comparison with nonsmokers' infants of the same age, and did not prevent elevation of ponderal index in comparison with nonsmokers' infants of the same weight and age.

High-dose chemotherapy for high-risk primary breast cancer: an on-site review of the Bezwoda study.

BACKGROUND: The efficacy of high-dose chemotherapy with progenitor-cell rescue for women with breast cancer is a controversial issue. Although historically controlled trials have suggested a survival advantage for high-dose chemotherapy, several randomised studies have yet to confirm this advantage. Two studies, however, by Bezwoda, of patients with high-risk and metastatic disease, seemed to show a significant survival advantage for high-dose compared with conventional-dose chemotherapy for metastatic and high-risk primary breast cancer. METHODS: To corroborate the study results before starting a large international confirmatory study, a US team did an on-site review of records for patients in the high-risk study. Limited numbers of records were made available for review, all of which were for patients who received the high-dose-chemotherapy regimen. FINDINGS: There was much disparity between the reviewed records and the data presented at two international meetings. In addition, the reviewers saw no signed informed consent, and the institutional review committee had no record of approval for the investigational therapy. After the site visit, Bezwoda admitted scientific misconduct by using a different control chemotherapy regimen from that described in presented data. INTERPRETATION: The Bezwoda study should not be used as the basis for further trials to test the efficacy of the cyclophosphamide, mitoxantrone, etoposide regimen for high-dose chemotherapy in women with high-risk primary breast cancer. This review validates the essential nature of on-site audits, especially in single-institution studies.

Maternal cigarette smoking during pregnancy and infant ponderal index at birth in the Swedish Medical Birth Register, 1991-1992.

OBJECTIVES: This study examined the effect of maternal smoking during pregnancy on infant body proportion. METHODS: The ponderal index, defined as birthweight divided by crown-heel length cubed, was examined in 207,607 infants from the Swedish Medical Birth Register for 1991 and 1992. RESULTS: Infant ponderal index was used as the outcome variable in an ordinary least squares continuous regression, which included early pregnancy smoking status, gestational age, and birthweight among the predictors. Ponderal index increased by 0.030 (+/- 0.0014) among infants of moderate smokers and by 0.040 (+/- 0.0017) among infants of heavy smokers, showing a dose response. CONCLUSIONS: Smoking differentially alters the trajectory of weight vs length growth in the fetus.

The relationship in neonates between clinically measured head circumference and brain volume estimated from head CT-scans.

OBJECTIVE: To determine if the frontal-occipital head circumference correlates with brain volume on CT and to investigate correlations between the volumes of different brain subdivisions in live neonates. METHODS: Records were studied from 27 neonates with anatomically normal head CT-scans which were ordered for clinical reasons, and which were performed at Johns Hopkins Hospital. Clinical data were abstracted from medical records. Brain volumes were estimated by digitizing the structures of interest on each slice of head CT-scans. RESULTS: In this sample of 27 infants with a mean birth weight of 3000.4 +/- 668 g, mean head circumference of 33.5 +/- 1.8 cm, and mean gestational age of 37 weeks and 4 days +/- 24 days, the mean of total brain volume was 333.0 +/- 78.3 ml. The correlation between clinically measured head circumference and total brain volume was 0.55 (P < 0.003). Regression of total brain volume on head circumference and its second and third powers accounted for 43% of the variation in total brain volume. Other predictor variables, namely infant race, sex, gestational age, and maternal age, were not significant in this regression once head circumference was included. The slope of the cubic function of head circumference as a predictor of brain volume was greatest below the mean head circumference of 33.5 cm. Brain volume leveled off at head circumferences greater than the mean. CONCLUSION: Head circumference is a powerful predictor of total brain volume in the neonate: below the approximate head-circumference mean of 33.5 cm, smaller head circumference indicates smaller total brain volume.

The effect of congenital anomalies on mortality risk in white and black infants.

OBJECTIVES: This population-based study examined the effect of all major congenital anomalies on the mortality of White and Black infants by infant sex, birthweight, gestational age, and lethality of the anomaly. The study also determined the total contribution of anomalies to infant mortality. METHODS: California Birth Defects Monitoring Program data were merged with linked birth-death files for 278,646 singleton non-Hispanic White and Black infants born in 1983 through 1986. Malformed infants were compared with nonmalformed infants to determine the effect of anomalies on mortality. RESULTS: The presence of any congenital anomaly increased mortality 9.0-fold (95% CI = 7.3, 11.1) for Black infants and 17.8-fold (95% CI = 16.2, 19.6) for White infants. Even "non-lethal" anomalies increased mortality up to 8.9-fold. Overall, anomalies contributed to 33% of White infant deaths, to 19% of Black infant deaths, and to over 60% of deaths among Black and White neonates weighing over 1499 g. CONCLUSIONS: The contribution of congenital anomalies to mortality of both low- (< 2500 g) and normal-birth-weight infants is substantially higher than previously estimated, representing a large public health problem for both Black and White infants.

Relation between very low birth weight and developmental delay among preschool children without disabilities.

The authors examined the relation between very low birth weight (VLBW: < 1,500 g) and possible developmental delay (DELAY) in the absence of frank developmental disability among young children. The prevalence of DELAY in a population-based cohort (Missouri resident births born from December 1989 through March 1991) of singleton VLBW children (n = 367) was compared with the prevalence of DELAY among both moderately low birth weight (MLBW: 1,500-2,499 g; n = 553) and normal birth weight (NBW: > or = 2,500 g; n = 555) singleton control children. DELAY was defined by nine measures of performance on the Denver Developmental Screening Test II at a median adjusted age of 15 months (range: 9-34 months). Subjects were asymptomatic for disabling conditions at developmental follow-up. Apparently well VLBW children were consistently at greater risk for both moderate and severe measures of DELAY and for DELAY across four functional areas than were either the MLBW (adjusted odds ratios: 1.4-2.7) or NBW children (adjusted odds ratios: 2.1-6.3). The greatest prevalence of DELAY tended to be among appropriate-for-gestational age VLBW children who were also the most premature. This study supports developmental follow-up of nondisabled VLBW children because of the significantly elevated risk for DELAY among apparently normal infants.

The relationship between prenatal health behavior advice and low birth weight.

OBJECTIVES: The purposes of the study were (a) to examine the relationship between the health behavior advice recommended by the Public Health Service Expert Panel on the Content of Prenatal Care and the risk of low birth weight and (b) to describe the type and frequency of health behavior advice offered to a group of pregnant women. METHODS: The authors used data from the National Institute of Child Health and Human Development/Missouri Maternal and Infant Health Survey, a follow-back survey of women who had delivered very low birth weight infants and of matched control subjects who had delivered moderately low birth weight and normal birth weight infants. Frequency distributions for different types of prenatal health behavior advice were examined for the 2205 participants, and logistic regression analyses were used to determine whether there was a relationship between birth weight and receiving the advice recommended by the Expert Panel. RESULTS: Only 10.4% of mothers reported receiving all seven types of health behavior advice recommended by the Expert Panel. Women who did not receive all seven types of advice were 1.5 times more likely to deliver a very low birth weight infant than a normal birth weight infant. CONCLUSIONS: Further research is needed to better understand the relationship between health education and birth weight.

Pregnancy wantedness and adverse pregnancy outcomes: differences by race and Medicaid status.

The relationship between pregnancy wantedness and adverse pregnancy outcomes was studied using data from 2,828 mothers who participated in the Missouri Maternal and Infant Health Survey. The wantedness of a pregnancy was measured using traditional classifications of mistimed and unwanted, as well as additional measures gauging how the woman felt about the pregnancy while she was pregnant. Fifty-eight percent of the very low birth weight infants and 59% of the moderately low birth weight infants resulted from unintended pregnancies, as did 62% of the normal-birth-weight infants. Logistic regression showed that mothers of very low birth weight infants were significantly more likely than those who had a normal-weight baby to report that they had felt unhappy about the pregnancy (odds ratio of 1.53). Very low birth weight was also associated with early denial of the pregnancy (1.54). Odds ratios associating these two unwantedness categories with low-birth-weight babies were higher among Medicaid recipients than among women not receiving Medicaid. Associations between very low birth weight and the denial variable were also significant among white women when very low birth weight outcomes were compared with normal outcomes, but there was no significant association among black women. There were no significant associations between low birth weight and the traditional unwantedness variables.

PIP: This study examines the relationship between pregnancy wantedness and adverse pregnancy outcomes among 2828 mothers who participated in the Missouri Maternal and Infant Health Survey. The survey was designed as a population-based case-control study of very low birth weight infants born to Missouri residents during December 1, 1989, and March 31, 1991. Infants of moderate and normal birth weight were the controls. Stillbirths were included, but multiple pregnancies were excluded. 36% of the sample were in-patients, 38% were Black, 62% were White, 23% were teenagers, 54% were in their 20s, 52% were married, and 52% lived in a major metropolitan area. 45% of mothers qualified for Medicaid. 779 women gave birth to a low birth weight infant, 799 gave birth to a moderately low birth weight infant, and 800 gave birth to a normal birth weight infant. 450 infants were stillbirths. Pregnancy wantedness was defined by traditional measures of mistimed and unwanted pregnancies as used in the NSFG and some newer measures, such as feelings about being pregnant. Six measures were used: unintended (mistimed and unwanted), mistimed, unwanted, unhappy about the pregnancy, unsure about the pregnancy, and denial of the pregnancy. Logistic regression analysis reveals that the odds of a pregnancy being unwanted if the baby was of low birth weight were greater for the following factors: smoking during pregnancy, maternal age, race, education, health status, pre-pregnancy weight-for-height, parity, infant mortality, and in-patient status at the survey date. The sample included 42% of mistimed pregnancies, and 15% each reported the pregnancy as unwanted, unhappy, or a denial. Birth weight outcomes did not vary by age or race. Low birth weight did not differentiate the wantedness of pregnancies using the timing-wantedness scale, but did distinguish on the happiness scale and denial measures.

Very-low-birthweight infants and income incongruity among African American and white parents in Chicago.

OBJECTIVES: Illinois vital records for 1982/1983 and US census income data for 1980 were analyzed to ascertain the relationship of income incongruity, race, and very low birthweight. METHODS: Positive income incongruity was considered present when study infants resided in wealthier neighborhoods than non-Latino Whites at the same level of parental education attainment and marital status. RESULTS: The odds ratios of very low birthweight for African Americans (n = 44,266) and Whites (n = 27,139) who experienced positive income incongruity were 0.7 (95% confidence interval [CI] = 0.5, 0.9) and 0.6 (95% CI = 0.5, 0.9), respectively. CONCLUSIONS: Positive income incongruity is associated with lower race-specific rates of very low birthweight.

Data linkage methods used in maternally-linked birth and infant death surveillance data sets from the United States (Georgia, Missouri, Utah and Washington State), Israel, Norway, Scotland and Western Australia.

In this paper we describe the methods used to link birth and infant mortality and morbidity surveillance data sets into sibships using deterministic or multistage probabilistic linkage methods. We describe nine linked data sets: four in the United States (Georgia, Missouri, Utah and Washington State), and four elsewhere (Scotland, Norway, Israel and Western Australia). Norway and Israel use deterministic methods to link births and deaths into sibships. The deterministic linkage is usually dependent on the availability of national identification numbers. In both countries they assign these numbers at birth. Deterministic linkage is usually highly successful, and the major problem is the validation of linkages. In the United States, Western Australia and UK linkage is multistage and probabilistic. This approach is usually dependent on the calculation linkage weights from sociodemographic variables. The success rates of probabilistic methods are above 80%. Maternally-linked perinatal data open new vistas for epidemiological research. Recurrence of poor perinatal outcomes is more appropriately studied using longitudinally-linked data sets. In addition, the emergence of risk factors and the recurrence of risk factors can be studied.

Does changing paternity contribute to the risk of intrauterine growth retardation?

An immune reaction initiated by paternal antigens may be necessary for healthy placental development, pregnancy maintenance and infant growth. An inadequate immune response may result in intrauterine growth retardation (IUGR). We hypothesised that a change in paternity may interfere with the immune response and cause poor placentation with resultant IUGR. In this paper we examine the risk of IUGR associated with changes in paternity. We used the Utah Successive Pregnancies Data Set that contains information on women across their pregnancies. We restricted the analysis to 141,817 women with two or three pregnancies. Women who did not have an IUGR infant in the previous pregnancy were at a 20-30% greater risk of developing IUGR if they had changed partners. Women who had a previous IUGR infant were at no increased risk for IUGR after a change in paternity. These results may point to an immune mechanism or may be as a result of residual confounding of unmeasured risk factors for IUGR. Further studies with data that contain more sociodemographic and biological risk factors for IUGR are necessary to exclude residual confounding.

Adolescent age at first pregnancy and subsequent obesity.

Adolescent pregnancy has been associated with subsequent obesity. This paper examines the patterns of obesity for second and third pregnancies among women who had their first singleton pregnancy as teenagers. We used maternally-linked data from 1978 to 1990 among 43,160 Missouri resident women. Age, parity, interpregnancy interval and prior body mass index were significantly associated with subsequent obesity among adolescents. Race, marital status and smoking had significant interactions with age. Among older women, being African-American and never having married was associated with an increased probability of obesity, and smoking had a greater effect on obesity at higher maternal age. Race and marital status did not have significant effects on obesity among younger women. The most important predictor of obesity was prior body mass index. Body mass index before the first pregnancy had a greater effect on subsequent obesity if the intervening interpregnancy weight gains were large. Excessive weight gain during pregnancy presents the health care provider with a dilemma. An increase in birthweight associated with high prenatal weight gains may diminish the risk of infant mortality and morbidity in an index pregnancy, but subsequent obesity may increase perinatal mortality rates, the rates of obstetric problems and neural tube defects.

PIP: This study examines the prevalence of obesity among American women who had an adolescent pregnancy in Missouri. Data were obtained from a maternally-linked longitudinal data set for the period 1978-90. The sample includes 103,262 births for first through fifth order singleton pregnancies linked to 43,160 Missouri mothers with a first pregnancy before the age of 20 years. Findings indicate that all women had at least two pregnancies. 31% had three pregnancies, 7% had four pregnancies, and 1% had five pregnancies. 8% were aged under 15 years at the first pregnancy, 35% were aged 16-17 years, and 57% were aged 18-19 years. A significantly higher number of higher birth order women had their first pregnancy when aged under 16 years. African American women were more likely to have their first pregnancy under 15 years of age, while White women were more likely to have their first pregnancy at 19 years. Medical risk factors decreased with age and increased with birth order. Cigarette smoking increased with age and with each pregnancy for all women. White women smoked more at every age and birth order. The rates of women in a subsample on Medicaid and food stamps decreased with age and increased with birth order. Rates of obesity increased with birth order. Rates increased from 3.8% for the first pregnancy to 16% for the fourth pregnancy. Women who were underweight at their first pregnancy had only a 0.5% increase in the rate of obesity from the first to second pregnancy, but overweight women had a 44.9% increase, and obese women had a 21% decrease in the rate of obesity. From the second to the fifth pregnancy, underweight women's rates of obesity are identified. Prior to the second and third pregnancy, the significant predictors of obesity were body mass index before the first pregnancy, interpregnancy weight gain, interpregnancy interval, race, medical risk factors, marital status, and smoking.

Evaluation of the effectiveness of a community-based enriched model prenatal intervention project in the District of Columbia.

OBJECTIVE: To evaluate an enriched prenatal intervention program designed to reduce the risk of low birth weight. STUDY SETTING: Freestanding community-based prenatal intervention project located in a poor inner-city community, serving mostly African American women. STUDY DESIGN: All women less than 29 weeks pregnant were eligible to participate. They were compared to women who lived in neighborhoods with similar rates of poverty. DATA COLLECTION: The birth certificate was the source of data on maternal age, education, marital status, timing and frequency of prenatal care attendance, parity, gravidity, prior pregnancy terminations, fetal and child deaths, and birth weight. PRINCIPAL FINDINGS: Thirty-eight percent of the women who delivered live-born infants in the study area participated in the program. There were no differences in low- and very low birthweight rates in the study and comparison groups. In a secondary analysis comparing participants and nonparticipants in the study census tracts, participants were at higher risk for low and very low birth weight, and they adhered more closely to the schedule of prenatal visits than nonparticipants. Low- and very low birthweight rates were lower among participants than among nonparticipants and comparison women. CONCLUSION: The Better Babies Project did not have an effect on the overall low- and very low birthweight rates in the study census tracts. This was probably due to the low participation rates and the high population mobility.

Toward a conceptualization of race in epidemiologic research.

This paper is a review of the prevailing conceptual basis of the use of race in health research. The author explores the current definitions of race in health research, and describes some of the history of race fabrication. In the examination of the association between race and disease the author describes black/white differences in age-adjusted mortality, infant mortality rates and birthweight. The analysis of race and disease is frustrated by incomplete theoretical constructs. Race, as used in health research, tends to be a unidimensional construct and the complex interplay between race and other social status variables is simplified. These problems are illustrated, and the author suggests a multidimensional construct of race.

Randomized comparison of home uterine activity monitoring and routine care in patients discharged after treatment for preterm labor.

OBJECTIVE: To determine whether home uterine activity monitoring reduces the likelihood of preterm birth in women successfully treated for preterm labor in their current pregnancies. METHODS: Women between 20-34 weeks' gestation who had been treated successfully for preterm labor were solicited to participate in a randomized clinical trial of home uterine activity monitoring versus routine high-risk care. The sample size of 56 was based on power calculations using the results of earlier investigators. Twenty-eight women were randomized to home uterine activity monitoring and 29 were assigned to the type of care appropriate for women discharged after hospitalization for parenteral treatment of preterm labor. One of the routine-care subjects was lost to follow-up. The two groups were comparable in distribution for race, insurance status, multiple gestation, marital status, gestational age at beginning of the study, and incidence of prior preterm birth. RESULTS: The 28 women receiving routine care had a 54% incidence of preterm birth, whereas the incidence was 57% in monitored women (relative risk 1.08, 95% confidence interval 0.6-1.9; P = .79). The incidences of delivery before 32 weeks and 34 weeks also were unaffected by the intervention. CONCLUSION: Home uterine activity monitoring is not effective in reducing the likelihood of preterm delivery in patients successfully treated for preterm labor in their current pregnancies.

Birth weight, gestational age and perinatal mortality: biological heterogeneity and measurement error.

At low birth weight the variance of last menstrual period based gestational age is wide and the distribution is positively skewed toward higher values. In this study the variance of gestational age decreases rapidly as birth weight increases, skewness decreases and kurtosis increases in approaching the mean of the birth weight distribution. Some of the wider variance and positive skewness of gestational age at low birth weight appears to reflect heterogeneity of intrauterine growth, in which infants with high values of gestational age are growth retarded. We show by partitioning each birth weight group into two groups of infants with different gestational age distributions, that at low birth weight, infants with low gestational ages have higher neonatal mortality rates but lower fetal mortality rates than infants with a higher gestational age for birth weight. The differences in mortality described between small infants at different gestational ages suggest that infants with a high LMP-based gestational age have experienced a slower rate of intrauterine growth. Some authors interpret the distributional characteristics as indications of systematic error in last menstrual period based assessment of gestational age. It appears from this study that the extent of systematic error in the estimation of LMP based gestational age may have been overstated in the past.

An analysis of gestational age, neonatal size and neonatal death using nonparametric logistic regression.

The relationship between gestational age, neonatal size and neonatal death is complex. To date, most authors have used birth weight as a proxy for neonatal size and have neglected to examine head circumference and crown heel length. In addition, they have assumed the size and gestational age were linearly related to neonatal death. In this study we use nonparametric multiple logistic regression to examine the relationship between gestational age, neonatal size and neonatal death. On its own, gestational age was nonlinearly associated with neonatal death. This nonlinearity disappeared with the addition of birth weight, crown heel length and head circumference. Birth weight, head circumference and crown heel length all had significant nonlinear associations with neonatal death in univariate analysis. With all factors in the model, birth weight and head circumference were nonlinearly associated with neonatal death and crown heel length was linearly associated with neonatal death. The complex relations between gestational age, neonatal size and neonatal death were explored with greater ease with nonparametric logistic regression.