Assessment of gestational age using birth certificate data compared with medical record data

Is residential proximity to polluted sites during pregnancy associated with preterm birth or low birth weight? Results from an integrated exposure database in North Carolina (2003-2015)

BACKGROUND

Preterm birth (PTB) and term low birth weight (LBW) have been associated with pollution and other environmental exposures, but the relationship between these adverse outcomes and specific characteristics of polluted sites is not well studied.

OBJECTIVES

We conducted a retrospective cohort study to examine relationships between residential proximity to polluted sites in North Carolina (NC) and PTB and LBW. We further stratified exposure to polluted sites by route of contaminant emissions and specific contaminants released at each site.

METHODS

We created an integrated exposure geodatabase of polluted sites in NC from 2002 to 2015 including all landfills, Superfund sites, and industrial sites. Using birth certificates, we assembled a cohort of 1,494,651 singleton births in NC from 2003 to 2015. We geocoded the gestational parent residential address on the birth certificate, and defined exposure to polluted sites as residence within one mile of a site. We used log-binomial regression models to estimate adjusted risk ratios (aRR) and 95% confidence intervals (CI). Binomial models were used to estimate adjusted risk differences (aRD) per 10,000 births and 95% CIs for associations between exposure to polluted sites and PTB or LBW.

RESULTS

We observed weak associations between residential proximity to polluted sites and PTB [aRR(95% CI): 1.07(1.06,1.09); aRD(95% CI): 61(48,74)] and LBW [aRR(95% CI): 1.09(1.06,1.12); aRD(95% CI): 24(17,31)]. Secondary analyses showed increased risk of both PTB and LBW among births exposed to sites characterized by water emissions, air emissions, and land impoundment. In analyses of specific contaminants, increased risk of PTB was associated with proximity to sites containing arsenic, benzene, cadmium, lead, mercury, and polycyclic aromatic hydrocarbons. LBW was associated with exposure to arsenic, benzene, cadmium, lead, and mercury.

SIGNIFICANCE

This study provides evidence for potential reproductive health effects of polluted sites, and underscores the importance of accounting for heterogeneity between polluted sites when considering these exposures.

IMPACT STATEMENT

We documented an overall increased risk of both PTB and LBW in births with gestational exposure to polluted sites using a harmonized geodatabase of three site types, and further examined exposures stratified by site characteristics (route of emission, specific contaminants present). We observed increased risk of both PTB and LBW among births exposed to sites with water emissions or air emissions, across site types. Increased risk of PTB was associated with gestational proximity to sites containing arsenic, benzene, cadmium, lead, mercury, and polycyclic aromatic hydrocarbons; increased risk of LBW was associated with exposure to arsenic, benzene, cadmium, lead, and mercury.

Critical evaluation of national vital statistics: the case of preterm birth trends in Portugal

INTRODUCTION

Using vital statistics, the Portuguese National Health Plan predicts that 14% of live births will be preterm in 2016. The prediction was based on a preterm birth rise from 5.9% in 2000 to 8.8% in 2009. However, the same source showed an actual decline from 2010 onwards. To assess the plausibility of national preterm birth trends, we aimed to compare the evolution of preterm birth and low birthweight rates between vital statistics and a hospital database.

MATERIAL AND METHODS

A time-trend analysis (2004-2011) of preterm birth (<37 gestational weeks) and low birthweight (<2500 g) rates was conducted using data on singleton births from the national birth certificates (n = 801,783) and an electronic maternity unit database (n = 21,392). Annual prevalence estimates, ratios of preterm birth:low birthweight and adjusted prevalence ratios were estimated to compare data sources.

RESULTS

Although the national prevalence of preterm birth increased from 2004 (5.4%), particularly between 2006 and 2009 (highest rate was 7.5% in 2007), and decreased after 2009 (5.7% in 2011), the prevalence at the maternity unit remained constant. Between 2006 and 2009, preterm birth was almost 1.4 times higher in the national statistics (using the national or the catchment region samples) than in the maternity unit, but no differences were found for low birthweight.

CONCLUSION

Portuguese preterm birth prevalence seems biased between 2006 and 2009, suggesting that early term babies were misclassified as preterm. As civil registration systems are important to support public health decisions, monitoring strategies should be taken to assure good quality data.

Vaginal birth after cesarean success in high-risk women: a population-based study

OBJECTIVE

The study aim was to identify factors associated with vaginal birth after cesarean (VBAC) in high-risk women.

STUDY DESIGN

This is a population-based retrospective cohort study of all births in Ohio during 2006 and 2007. High-risk patients were defined as singleton gestations in women with one previous cesarean who had ⩾1 of the following risk factors: body mass index (BMI)⩾30, hypertension, or diabetes. Multivariate logistic regression was utilized to estimate the relative influence of each factor on successful VBAC.

RESULT

A total of 280 882 births were analyzed: of them, 79 084 (27.1%) were high-risk pregnancies and 8658 (10.9%) women had undergone one previous cesarean; 1433 (16.6%) underwent a trial of labor after cesarean (TOLAC). Of them, 974 (68.0%) had a successful VBAC, whereas 459 (32.0%) did not. Factors significantly associated with VBAC success were as follows: a prior vaginal delivery; pregnancy weight gain ⩽30 lbs; Caucasian race; and labor augmentation.

CONCLUSION

High-risk women with one prior cesarean are unlikely to undergo a TOLAC, but have a high rate of VBAC.

The influence of mode of delivery on breastfeeding initiation in women with a prior cesarean delivery: a population-based study

OBJECTIVE

This study compared breastfeeding initiation following repeat cesarean delivery, successful vaginal birth after cesarean (VBAC), and unsuccessful trial of labor.

SUBJECTS AND METHODS

We performed a population-based retrospective cohort study of Ohio births (2006-2007) with a previous cesarean delivery. The primary outcomes were breastfeeding initiation rates among women with a previous cesarean delivery. Breastfeeding initiation rates were compared among three different delivery types: repeat cesarean delivery, successful VBAC, and unsuccessful trial of labor. Sociodemographic factors, medical risk factors, and pregnancy-related risk factors were also compared to assess influence on breastfeeding initiation rates.

RESULTS

Women delivered by successful VBAC were 47% more likely to initiate breastfeeding than women delivered by scheduled repeat cesarean (adjusted relative risk 1.47; 95% confidence interval 1.35, 1.60). Women who ultimately delivered by cesarean section with unsuccessful trial of labor were also more likely to breastfeed than women with a scheduled repeat cesarean section (61% vs. 58.7%, respectively) (adjusted relative risk 1.17; 95% confidence interval 1.04, 1.33).

CONCLUSIONS

Patients who undergo a scheduled repeat cesarean delivery are less likely to initiate breastfeeding. Women who attempt and succeed in achieving vaginal birth after a previous cesarean section are more likely to breastfeed than are women who deliver by repeat cesarean section. Also, those women who ultimately deliver by cesarean section after an unsuccessful trial of labor were also more likely to breastfeed than those women with a scheduled repeat cesarean section. This suggests there are influences on patient choice for delivery that also may influence the patient's decision to breastfeed.

Pregnancy characteristics and maternal breast cancer risk: a review of the epidemiologic literature

The short- and long-term effects of pregnancy on breast cancer risk are well documented. Insight into potential biological mechanisms for these associations may be gained by studying breast cancer risk and pregnancy characteristics (e.g., preeclampsia, twining), which may reflect hormone levels during pregnancy. To date, no review has synthesized the published literature for pregnancy characteristics and maternal breast cancer using systematic search methods. We conducted a systematic search to identify all published studies. Using PUBMED (to 31 July 2009), 42 relevant articles were identified. Several studies suggest that multiple births may be associated with a lowered breast cancer risk of about 10-30%, but results were inconsistent across 18 studies. The majority of 13 studies suggest about a 20-30% reduction in risk with preeclampsia and/or gestational hypertension. Six of seven studies reported no association for infant sex and breast cancer risk. Data are sparse and conflicting for other pregnancy characteristics such as gestational age, fetal growth, pregnancy weight gain, gestational diabetes, and placental abnormalities. The most consistent findings in a generally sparse literature are that multiple births and preeclampsia may modestly reduce breast cancer risk. Additional research is needed to elucidate associations between pregnancy characteristics, related hormonal profiles, and breast cancer risk.

Ambient air pollutant concentrations during pregnancy and the risk of fetal growth restriction

BACKGROUND

Previous studies of air pollution and birth outcomes have not evaluated whether complicated pregnancies might be susceptible to the adverse effects of air pollution. It was hypothesised that trimester mean pollutant concentrations could be associated with fetal growth restriction, with larger risks among complicated pregnancies.

METHODS

A multiyear linked birth certificate and maternal/newborn hospital discharge dataset of singleton, term births to mothers residing in New Jersey at the time of birth, who were white (non-Hispanic), African-American (non-Hispanic) or Hispanic was used. Very small for gestational age (VSGA) was defined as a fetal growth ratio <0.75, small for gestational age (SGA) as > or =0.75 and <0.85, and 'reference' births as > or =0.85. Using polytomous logistic regression, associations between mean pollutant concentrations during the first, second and third trimesters and the risks of SGA/VSGA were examined, as well as effect modification of these associations by several pregnancy complications.

RESULTS

Significantly increased risk of SGA was associated with first and third trimester PM(2.5) (particulate matter <2.5 microm in aerodynamic diameter), and increased risk of VSGA associated with first, second and third trimester nitrogen dioxide (NO(2)) concentrations. Pregnancies complicated by placental abruption and premature rupture of the membrane had approximately two- to fivefold greater excess risks of SGA/VSGA than pregnancies not complicated by these conditions, although these estimates were not statistically significant.

CONCLUSIONS

These findings suggest that ambient air pollution, perhaps specifically traffic emissions during early and late pregnancy and/or factors associated with residence near a roadway during pregnancy, may affect fetal growth. Further, pregnancy complications may increase susceptibility to these effects in late pregnancy.

Menstrual versus clinical estimate of gestational age dating in the United States: temporal trends and variability in indices of perinatal outcomes

Accurate estimation of gestational age early in pregnancy is paramount for obstetric care decisions and for determining fetal growth and other conditions that may necessitate timing the iatrogenic intervention or delivery. We sought to examine temporal changes in the distributions of two measures of gestational age, namely, those based on menstrual dating and a clinical estimate. We further sought to evaluate relative comparisons and variability in indices of perinatal outcomes. We utilised the Natality data files in the US, 1990-2002 comprising women that delivered a singleton livebirth between 22 and 44 weeks gestation (n = 42 689 603). Changes were shown in the distributions of gestational age based on menstrual vs. clinical estimate between 1990 and 2002, as well as changes in the proportions of preterm (<37, <32 and <28 weeks) and post-term (>or=42 weeks) birth, and small- (SGA; <10th percentile) and large-for-gestational-age (LGA; birthweight >90th percentile) births. While the absolute rates of preterm birth <37 weeks, SGA and LGA births were lower based on the clinical estimate of gestational age relative to that based on menstrual dating, the increases in preterm birth rate between 1990 and 2002 were fairly similar between the two measures of gestational dating. However, the decline in post-term births was larger, based on the clinical estimate (-73.8%), than on the menstrual estimate (-36.6%) between 1990 and 2002. While the clinical estimate of gestational age appears to provide a reasonably good approximation to the menstrual estimate, disregarding the clinical estimate of gestational age may ignore the advantages of gestational age assessment in modern obstetrics.

Assessing the quality of last menstrual period date on California birth records

Birth certificate last menstrual period (LMP) date is widely used to estimate gestational age in the US. While data quality concerns have been raised, no large population-based study has isolated data quality issues by comparing birth record LMP (Birth LMP) with reliable LMP dates from another source. We assessed LMP data quality in 2002 California singleton livebirth records (n = 515 381) and in a subset of records with linked prenatally collected LMP from California's statewide Prenatal Expanded Alpha-fetoprotein Screening Program (XAFP) (n = 105 936). Missing or incomplete LMP data affected 13% of birth records; 17% of those had complete LMP within XAFP records. Data quality indicators supported XAFP LMP as more accurate than Birth LMP, with a lower prevalence of digit preference, post-term delivery, out-of-range gestational age estimates and implausible birthweight-for-gestational age. The bimodal birthweight distribution evident at 20-31 weeks' gestation based on Birth LMP was nearly absent with XAFP LMP-based gestational age. Approximately 32% of the second birthweight mode was explained by apparent clerical errors in Birth LMP month. Digit preference errors, particularly day 1, were associated with gestational age overestimation. Preterm delivery rates were higher according to Birth (7.6%) vs. XAFP LMP (7.2%). One-fifth of observed preterm and over half of observed post-term births using Birth LMP were not true cases; 15% of true preterm cases were missed. African American or Hispanic, less educated, and publicly or uninsured women were most likely to be misclassified and have large LMP date discrepancies attributable to clerical or digit preference error. The implementation of a revised birth certificate is an opportunity for targeted training and data entry checks that could substantially improve LMP accuracy on birth records.

Accuracy of birth certificate data by risk factors and outcomes: analysis of data from New Jersey

OBJECTIVE

The purpose of this study was to determine the extent to which the accuracy of birth certificate data varies by risk factors and birth outcomes.

STUDY DESIGN

We reanalyzed data from a validation study of birth certificate data in New Jersey, focusing on subgroups of mothers according to marital status, age, race, ethnicity, English-language proficiency, prenatal care, transfer status, birthweight, and gestational age.

RESULTS

Underreporting of birth certificate data elements varies by maternal characteristics (particularly English-language proficiency), transfer status, and birth outcomes.

CONCLUSION

It is important to consider subgroup variations in data quality when birth certificate data are used for research. Additional studies are needed to explore the sources of variation in data quality and to assess the quality for additional subgroups, across subgroups in other states, in low-risk populations, and of new data items that were introduced in the 2003 revision of the US Standard Certificate of Live Birth.

Perinatal exposures and breast cancer risk in the Western New York Exposures and Breast Cancer (WEB) Study

BACKGROUND

There is increasing evidence that early life exposures, such as birth weight, infant feeding practices, birth rank and maternal age at delivery may play a role in breast carcinogenesis.

METHODS

We conducted a case-control study of women aged 35-80 in Western New York (Western New York Exposure and Breast Cancer Study, the WEB Study, 1996-2001). The study included 845 women diagnosed with primary, incident, histologically confirmed breast cancer, and 1538 controls frequency-matched to cases on age, race, and county of residence. We conducted extensive in-person interviews including self-reported birth weight, history of having been breastfed, birth rank, and maternal age at delivery.

RESULTS

Birth weight was significantly associated with pre- but not post-menopausal breast cancer risk. Compared to women whose birth weight was 5.5-7 pounds, we found an increased risk associated with a birth weight greater than 8.5 pounds (OR 1.84, 95%CI: 1.12-3.02). Risk was also increased for pre- but not post-menopausal women who had not been breastfed (OR 1.78, 95%CI: 1.21-2.60). Birth order and maternal age at delivery were not significantly associated with breast cancer risk.

CONCLUSIONS

Our findings are consistent with other studies showing breast cancer risk associated with birth weight for pre- but not post-menopausal breast cancer. As we found in an earlier study, having been breastfed was associated with decreased risk. These findings add to the accumulating evidence that early life events impact women's subsequent breast cancer risk.

The reliability and validity of birth certificates

OBJECTIVES

To summarize the reliability and validity of birth certificate variables and encourage nurses to spearhead data improvement.

DATA SOURCES

A Medline key word search of reliability and validity of birth certificate, and a reference review of more than 60 articles were done.

STUDY SELECTION

Twenty-four primary research studies of U.S. birth certificates that involved validity or reliability assessment.

DATA EXTRACTION

Studies were reviewed, critiqued, and organized as either a reliability or a validity study and then grouped by birth certificate variable.

DATA SYNTHESIS

The reliability and validity of birth certificate data vary considerably by item. Insurance, birthweight, Apgar score, and delivery method are more reliable than prenatal visits, care, and maternal complications. Tobacco and alcohol use, obstetric procedures, and delivery events are unreliable. Birth certificates are not valid sources of information on tobacco and alcohol use, prenatal care, maternal risk, pregnancy complications, labor, and delivery.

CONCLUSIONS

Birth certificates are a key data source for identifying causes of increasing U.S. infant mortality but have serious reliability and validity problems. Nurses are with mothers and infants at birth, so they are in a unique position to improve data quality and spread the word about the importance of reliable and valid data. Recommendations to improve data are presented.

Birth characteristics and brain cancers in young children

BACKGROUND

High birthweight is a potential risk factor for childhood brain tumours, particularly astrocytomas. We investigated several birth characteristics in relationship to brain cancers in young children.

METHODS

We obtained 849 invasive central nervous system (CNS) cancer cases, ages 0-4 years, from California's population-based cancer registry for 1988-1997. We matched 746 (88%) of these cases to a California live birth certificate. We randomly selected two control birth certificates for each case, matched on date of birth and gender. We used conditional logistic regression to obtain odds ratios (OR) and 95% CI. The birth characteristics examined included birthweight, gestational age, race, parental age, and parental education.

RESULTS

Analysing all CNS tumours combined, we found that children of other racial/ ethnic groups had OR below one compared with non-Hispanic white children. When adjusted for gestational age, race/ethnicity, and mother's place of birth, the OR for high birthweight (>/=4000 g) was 1.05 (95% CI: 0.79-1.38) compared with children with birthweights of 2500-3999 g. For astrocytomas (313 cases), the adjusted OR for high birthweight was 1.40 (95% CI: 0.90-2.18). When parental education was included in the model (available for only a subset of the birth years), the adjusted OR was 1.71 (95% CI: 1.01-2.90). High birthweight did not appear to be a risk factor for primitive neuroectodermal tumours (PNET).

CONCLUSIONS

We found high birthweight associated with increased risk of astrocytomas, but not PNET, in young children.

The risk of mortality or cerebral palsy in twins: a collaborative population-based study

The purpose of the paper was to describe demographic and clinical factors associated with fetal or neonatal death or cerebral palsy (CP) in twins. Vital statistics from five populations in the United States and Australia, which included information on CP diagnosed after 1 y of age. Information on zygosity was not available. In 1,141,351 births, 25,772 of whom were twins, significant secular trends from 1980 to 1989 included increasing prevalence of twins, increasing proportion of unlike-sex twins, and increasing maternal age. Overall, twins were at an approximately 5-fold increased risk of fetal death, 7-fold increased risk of neonatal death, and 4-fold increased risk of CP compared with singletons. However, at birth weight <2500 g, twins generally did better than singletons, both with respect to mortality and to CP rates. Second-born twins and twins from same-sex pairs were at increased risk of early death but not of CP. Twins from growth-discordant pairs and twins whose co-twin died were at increased risk of both mortality and CP. The highest rates of CP were in surviving twins whose co-twin was still-born (4.7%), died shortly after birth (6.3%) or had CP (11.8%). In this large data set spanning a 10-y period, overall rates of death or cerebral palsy were higher in twins than singletons, although small twins generally did better than small singletons. Co-twin death was a strong predictor of CP in surviving twins. This risk was the same for same- and different-sex pairs, and observed both for preterm and term infants.

Trends and characteristics of induced labour in the United States, 1989-98

Induction of labour is one of the fastest growing medical procedures in the United States. In 1998, 19.2% of all US births were a product of induced labour, more than twice the 9.0% in 1989. Induction of labour has been efficacious in the management of post-term pregnancy and in expediting delivery when the mother or infant is sufficiently ill to make continuation of the pregnancy hazardous. However, the recent rapid increase in induction, and particularly the doubling of the induction rate for preterm pregnancies (from 6.7% in 1989 to 13.4% in 1998), has generated concern among some clinicians. The present study uses vital statistics natality data to examine the epidemiology of induced labour in the US. Multivariable analysis is used to examine the probability of having an induced delivery in relation to a wide variety of socio-demographic and medical characteristics, and also in relation to relative indications and contraindications for induced labour as outlined by the American College of Obstetricians and Gynecologists (ACOG). Induction rates were higher for women who were non-Hispanic white, college educated, born in the US, primaparae and those with intensive prenatal care utilisation. Induction rates were also higher for women with various medical conditions including hypertension, eclampsia and renal disease. For non-Hispanic white women with singleton births, 59% of the increase in the preterm birth rate from 1989 to 1998 can be accounted for by the increase in preterm inductions. The adjusted odds ratio for neonatal mortality among preterm births with induced labour was 1.20 [95% confidence interval 1.11, 1.31]. The rapid increase in induction rates, particularly among preterm births, marks a shift in the obstetric management of pregnancy. More detailed studies are needed to examine physician decision-making protocols, particularly for preterm induction, and to assess the impact of these practice changes on patient outcomes.

A comparison of risk factors for twin preterm birth in the United States between 1981-82 and 1996-97

OBJECTIVE

This paper examines risk factors for twin preterm birth in 1981-82 and 1996-97 in the United States in order to see if they have changed over time.

METHODS

We studied all U.S. twin births for the years examined (N = 346, 567). Since the gestational age distributions for twins differs from singletons, the risk of preterm birth was examined at <33, 33-34, and 35-36 weeks. Logistic regression was used to examine the contributions of sociodemographic and obstetric factors at each period.

RESULTS

While the <33 week twin preterm rate rose 7% from 1981-82 to 1996-97, the 33-34-week rate rose 31%, and the 35-36-week rate rose 51%. Women with less education, teenagers, unmarried women, primiparas, and blacks were more likely to deliver preterm across all three preterm birth levels. However, the effect of these low socioeconomic status markers diminished over the study period. Additionally, the odds of preterm birth among blacks increased with earlier gestational ages. Women who had intensive prenatal care utilization as compared with less than adequate utilization were more likely to deliver preterm (35-36 weeks) in 1996-97 (odds ratio (OR) = 2.05) compared with 1981-82 (OR = 1.44). Smaller increases were noted for <33 and 33-34 weeks.

CONCLUSIONS

Obstetric factors appear to be playing a greater role in the rise of twin preterm births at 35-36 weeks gestation. Temporal sociodemographic changes do not explain the rise in the preterm rate. Changing clinical practices may be having unintended consequences on the public health goals of reducing preterm and low birthweight rates in the United States.

Incomplete birth certificates: a risk marker for infant mortality

OBJECTIVES

This study assessed the relationship between incomplete birth certificates and infant mortality.

METHODS

Birth certificates from California (n = 538 945) were assessed in regard to underreporting of 13 predictors of perinatal outcomes and mortality.

RESULTS

Of the birth certificates studied, 7.25% were incomplete. Underreporting was most common in the case of women at high risk for poor perinatal outcomes and infants dying within the first day. Increasing numbers of unreported items were shown to be associated with corresponding increases in neonatal and postneonatal mortality rates.

CONCLUSIONS

Incomplete birth certificates provide an important marker for identifying high-risk women and vulnerable infants. Because data "cleaning" will result in the removal of mothers and infants at highest risk, birth certificate analyses should include incomplete records.

Validity of birth certificate data for the outcome of the previous pregnancy, Georgia, 1980-1995

The author evaluated the validity of four historically based variables collected on Georgia birth certificates: outcome of preceding pregnancy, history of delivery of a low- (<2,500 g) or high- (>4,000 g) birth-weight infant, and death of the baby resulting from the preceding pregnancy. Data were derived from birth and fetal death certificates that were linked for the first and second deliveries of 231,075 women in Georgia from 1980 through 1995. Deaths that occurred during the infant's first year of life were also linked to the birth certificate. For all but the survival variable, the outcome of the first birth as reported on the certificate for the second birth was compared with the outcome recorded on the certificate for the first birth, which was assumed to be correct. Except for ascertainment of death of the firstborn infant, sensitivities for the history of poor outcomes were low. Furthermore, sensitivities were higher when an extremely adverse outcome occurred in the first pregnancy or an adverse outcome recurred. The only high sensitivity was for past infant death (85.4%). These results suggest caution when using these variables to identify high-risk subsets for further research or control for confounding.

Risk for birth defects among premature infants: a population-based study

OBJECTIVE

To investigate the relationship between prematurity and birth defects.

STUDY DESIGN

In a population-based cohort study, infants with birth defects were ascertained through the Metropolitan Atlanta Congenital Defects Program, a surveillance system with active methods of ascertainment. Gestational age data were obtained from birth certificates of liveborn, singleton infants with and without birth defects born in the 5-county metropolitan Atlanta area.

RESULTS

Among 264,392 infants with known gestational ages born between 1989 and 1995, 7738 were identified as having birth defects (2.93%). Premature infants (<37 weeks' gestation) were more than two times as likely to have birth defects than term infants (37-41 weeks) (risk ratio = 2.43; 95% CI 2.30-2.56). This relationship was evident for several categories of birth defects. The rate of birth defects varied by gestational age categories, with the highest risk in the 29- to 32-week gestational age category (risk ratio = 3.37).

CONCLUSIONS

The risk for birth defects is increased in premature infants. Awareness of this relationship is important for clinicians caring for premature infants. The morbidity and mortality associated with a particular defect may be significantly altered by the presence of prematurity. Further study of this association may provide insight into the etiology of these relatively common problems.

Birth characteristics and subsequent risk for breast cancer in very young women

There is growing evidence that prenatal exposures may influence later breast cancer risk. This matched case-control study used linked New York State birth and tumor registry data to examine the association between birth characteristics and breast cancer risk among women aged 14-37 years. Cases were women diagnosed with breast cancer between 1978 and 1995 who were also born in New York after 1957 (n = 484). For each case, selected controls were the next six liveborn females with the same maternal county of residence. The authors found a J-shaped association between birth weight and breast cancer risk, and very high birth weight (> or =4,500 g) was associated with the greatest elevation in risk (adjusted odds ratio (OR) = 3.10, 95% confidence interval (CI): 1.18, 7.97). The association of maternal age with breast cancer risk was also J-shaped, with maternal age of more than 24 years showing a positive, linear association (adjusted OR = 1.94, 95% CI: 1.18, 3.18 for maternal age > or =35 vs. 20-24 years; p for trend = 0.02). In contrast, women born very preterm had a lower risk (adjusted OR = 0.11, 95% CI: 0.02, 0.79 for gestational age <33 vs. > or =37 weeks). These findings support a role for early life factors in the development of breast cancer in very young women.

Outcomes of 17,137 pregnancies in 2 urban areas of Ukraine

OBJECTIVES

Frequent terminations of pregnancy and high rates of fetal loss have been reported, but not confirmed, in the former eastern bloc. A census of pregnancies in Ukraine, a former eastern bloc country, was conducted to determine the rates of these events.

METHODS

All pregnancies registered in 2 urban areas were enumerated. During a 19-month period between 1992 and 1994, 17,137 pregnancies and their outcomes were recorded.

RESULTS

Sixty percent of the pregnancies were voluntarily terminated, generally before the 13th week. In pregnancies delivered at 20+ weeks, fetal mortality was 29 per 1000, nearly 5 times the rate among Whites in the United States. There was a greater proportion of very early deliveries (20-27 weeks) in Ukraine, as well as higher death rates at all gestational ages. Perinatal mortality was estimated to be 35 per 1000, about 3 times the US rate.

CONCLUSIONS

This is believed to be the first study in the former eastern bloc to ascertain all of the clinically recognized pregnancies in a specified period and to determine their outcomes. The data document elevated reproductive risks in a former Soviet state.

Racial differences in the patterns of singleton preterm delivery in the 1988 National Maternal and Infant Health Survey

OBJECTIVES

To determine if the association between race and preterm delivery would persist when preterm delivery was partitioned into two etiologic pathways.

METHODS

We evaluated perinatal and obstetrical data from the 1988 National Maternal and Infant Health Survey and classified preterm delivery as spontaneous or medically indicated. Discrete proportional hazard models were fit to assess the risk of preterm delivery for Black women compared with White women adjusting for potential demographic and behavioral confounding variables.

RESULTS

Preterm delivery occurred among 17.4% of Black births and 6.7% of White births with a Black versus White unadjusted hazard ratio (HR) of 2.8 (95% CI = 2.4-3.3). The adjusted HR for a medically indicated preterm delivery showed no racial difference in risk (HR = 1.0, 95% CI = 0.4-2.6). However, for spontaneous preterm delivery between 20 and 28 weeks gestation, the Black versus White adjusted hazard ratio (HR) was 4.9 (95% CI = 3.4-7.1).

CONCLUSIONS

Although we found an increased unadjusted HR for preterm delivery among Black women compared with White women, the nearly fivefold increase in adjusted HR for the extremely preterm births and the absence of a difference for medically indicated preterm delivery was unexpected. Given the differences in the risks of preterm birth between Black and White women, we recommend to continue examining risk factors for preterm delivery after separating spontaneous from medically indicated preterm birth and subdividing preterm delivery by gestational age to shed light on the reasons for the racial disparity.

Reliability of placental histology using archived specimens

Archived placental materials provide a resource for retrospective studies of perinatal outcomes. Using archived specimens, we evaluated inter-rater reliability in the assessment of placental histological features possibly associated with neonatal illness and long-term neurological outcome. Five expert placental pathologists independently reviewed archived placental specimens on 30 subjects born during 1983-85 in six different hospitals. Moderate to substantial agreement among the raters was observed for a variety of indicators of inflammation, presence of macrophages with pigment and indicators of villous maturity, increased syncytial knots and maternal vasculopathy. Existing pathology reports for these specimens from routine histology examinations conducted at the time of delivery were in substantial agreement with expert review for the presence of any subchorionitis/chorionitis/chorioamnionitis. In conclusion, considerable inter-rater agreement was observed for several relatively common and potentially important placental findings. Archived placental materials and pathology reports may be useful in retrospective studies.