Birth complication reporting: the effect of birth certificate design

Gestational Age of Delivery in Pregnancies Complicated by Diabetes

Background: The recommended gestational age to deliver pregnancies complicated by diabetes ranges from 34 to 39 weeks of gestation. The objective of this study was to determine the optimal gestational age for delivery of patients with diabetes to minimize perinatal death. Methods: We extracted a population-based cohort of singleton, nonanomalous infants of diabetic pregnancies from the Missouri birth registry for the period January 1, 1989 to December 31, 2005 and compared perinatal outcomes of planned deliveries at 37, 38, 39, and 40 weeks to expectant management. Planned deliveries were identified by induction or cesarean delivery without documented medical or obstetric indications. The primary outcome was perinatal death, defined as stillbirth or neonatal death within 28 days of birth. Secondary outcomes were independent stillbirth, independent neonatal death, and a composite adverse neonatal event of assisted ventilation >30 minutes, birth injury, seizures, or 5-minute Apgar score ≤3. Groups were compared using t test and chi-square as appropriate. Results: In 4,905 diabetic pregnancies reaching 37 weeks, 1,012 (20.6%) patients were insulin dependent. Overall, the risk of perinatal death at any gestational age examined was low (3/1,000 births or lower), as was the risk of the adverse perinatal outcome (<2%). When only patients who were insulin dependent were included in the analysis, the risk of perinatal death at any gestational age remained low at 6 per 1,000 births or fewer. Conclusion: Delivery as early as 37 weeks is reasonable for women who have diabetes, although the absolute risk of perinatal death is low at 37 to 39 weeks.

A Family-Based Study of the Association Between Labor Induction and Offspring Attention-Deficit Hyperactivity Disorder and Low Academic Achievement

The current study examined associations between labor induction and both (1) offspring attention-deficit hyperactivity disorder (ADHD) diagnosis in a Swedish birth cohort born 1992-2005 (n = 1,085,008) and (2) indices of offspring low academic achievement in a sub-cohort born 1992-1997 (n = 489,196). Associations were examined in the entire sample (i.e., related and unrelated individuals) with adjustment for measured covariates and, in order to account for unmeasured confounders shared within families, within differentially exposed cousins and siblings. We observed an association between labor induction and offspring ADHD diagnosis and low academic achievement in the population. However, these associations were fully attenuated after adjusting for measured covariates and unmeasured factors that cousins and siblings share. The results suggest that observed associations between labor induction and ADHD and low academic achievement may be due to genetic and/or shared environmental factors that influence both mothers' risk of labor induction and offspring neurodevelopment.

Evaluation of the Sensitivity and Accuracy of Birth Defects Indicators on the 2003 Revision of the U.S. Birth Certificate: Has Data Quality Improved?

BACKGROUND

The 2003 revision of the U.S. Birth Certificate was restricted to birth defects readily identifiable at birth. Despite being the lone source of birth defects cases in some studies, we lack population-based information on the quality of birth defects data from the most recent revision of the birth certificate.

METHODS

We linked birth certificate data to confirmed cases from the Florida Birth Defects Registry (FBDR) to assess the sensitivity and positive predictive value (PPV) of birth defects indicators on the birth certificate. Descriptive statistics and log-binomial regression were used to examine variation in data quality measures by defect type and other characteristics. We also evaluated the contribution of birth certificates as a case ascertainment source for the FBDR.

RESULTS

Sensitivity of the birth certificate was poor (19.1%) with variation across defects ranging from 55% for anencephaly and 54% for gastroschisis, to <10% for other defects. PPV was better (87.1%) and ranged from >93% for orofacial clefts and gastroschisis to <55% for anencephaly and limb reduction defects. We also observed variation in data quality across maternal, infant, and hospital characteristics. Of cases identified by the birth certificate and not any other FBDR data source, 54.9% were false-positive diagnoses.

CONCLUSIONS

Efforts to restrict the 2003 revision of the birth certificate to defects identifiable at birth have not improved the likelihood that birth certificates will identify infants born with those defects. We do not recommend the use of birth certificates as a source of birth defects data without case verification strategies.

Association of Labor Induction With Offspring Risk of Autism Spectrum Disorders

IMPORTANCE

Induction of labor is a frequently performed obstetrical intervention. It would thus be of great concern if reported associations between labor induction and offspring risk of autism spectrum disorders (ASD) reflected causal influence.

OBJECTIVE

To assess the associations of labor induction with ASD, comparing differentially exposed relatives (siblings and cousins discordant for induction).

DESIGN, SETTING, AND PARTICIPANTS

Follow-up of all live births in Sweden between 1992 and 2005, defined in the Medical Birth Register. The register was linked to population registers of familial relations, inpatient and outpatient visits, and education records. Diagnoses of ASD were from 2001 through 2013, and data were analyzed in the 2015-2016 year.

EXPOSURES

Induction of labor.

MAIN OUTCOMES AND MEASURES

Autism spectrum disorders identified by diagnoses from inpatient and outpatient records between 2001 and 2013. Hazard ratios (HRs) quantified the association between labor induction and offspring ASD. In addition to considering a wide range of measured confounders, comparison of exposure-discordant births to the same woman allowed additional control for all unmeasured factors shared by siblings.

RESULTS

The full cohort included 1 362 950 births, of which 22 077 offspring (1.6%) were diagnosed with ASD by ages 8 years through 21 years. In conventional models of the full cohort, associations between labor induction and offspring ASD were attenuated but remained statistically significant after adjustment for measured potential confounders (HR, 1.19; 95% CI, 1.13-1.24). When comparison was made within siblings whose births were discordant with respect to induction, thus accounting for all environmental and genetic factors shared by siblings, labor induction was no longer associated with offspring ASD (HR, 0.99; 95% CI, 0.88-1.10).

CONCLUSIONS AND RELEVANCE

In this nationwide sample of live births we observed no association between induction of labor and offspring ASD within sibling comparison. Our findings suggest that concern for ASD should not factor into the clinical decision about whether to induce labor.

Availability of Lactation Counseling Services Influences Breastfeeding among Infants Admitted to Neonatal Intensive Care Units

Purpose.

To assess the association between the presence of international board-certified lactation consultant (IBCLC) services at a delivery hospital and the breastfeeding practices of women whose infants required neonatal intensive care unit (NICU) admission.

Design.

Cross-sectional study using population-level data.

Setting.

Philadelphia, Pennsylvania.

Subjects.

2132 infants admitted to the NICU.

Measures.

Breastfeeding at hospital discharge was measured with the question, “Is the infant being breastfed?” Delivery hospitals were dichotomized as to the presence or absence of an IBCLC on staff.

Analysis.

Logistic regression was used to assess the relationship between breastfeeding at discharge and the presence of an IBCLC at the delivery facility while adjusting for maternal characteristics and birth outcomes.

Results.

Among mothers of infants admitted to the NICU, breastfeeding rates among mothers who delivered at hospitals with an IBCLC were nearly 50% compared with 36.9% among mothers who delivered at hospitals without an IBCLC. The adjusted odds of breastfeeding initiation prior to hospital discharge were 1.34 (95% confidence interval = 1.03, 1.76) times higher for women who delivered at a facility with an IBCLC.

Conclusions.

To increase breastfeeding rates among the NICU population, these findings support the need for universal availability of IBCLCs at delivery facilities that have NICUs.

Reassessing the impact of smoking on preeclampsia/eclampsia: are there age and racial differences?

OBJECTIVE

To investigate the association between cigarette use during pregnancy and pregnancy-induced hypertension/preeclampsia/eclampsia (PIH) by maternal race/ethnicity and age.

METHODS

This retrospective cohort study was based on the U.S. 2010 natality data. Our study sample included U.S. women who delivered singleton pregnancies between 20 and 44 weeks of gestation without major fetal anomalies in 2010 (n = 3,113,164). Multivariate logistic regression models were fit to estimate crude and adjusted odds ratios and the corresponding 95% confidence intervals.

RESULTS

We observed that the association between maternal smoking and PIH varied by maternal race/ethnicity and age. Compared with non-smokers, reduced odds of PIH among pregnant smokers was only evident for non-Hispanic white and non-Hispanic American Indian women aged less than 35 years. Non-Hispanic Asian/Pacific Islander women who smoked during pregnancy had increased odds of PIH regardless of maternal age. Non-Hispanic white and non-Hispanic black women 35 years or older who smoked during pregnancy also had increased odds of PIH.

CONCLUSION

Our study findings suggest important differences by maternal race/ethnicity and age in the association between cigarette use during pregnancy and PIH. More research is needed to establish the biologic and social mechanisms that might explain the variations with maternal age and race/ethnicity that were observed in our study.

Gestational Weight Gain and Maternal and Neonatal Outcomes in Term Twin Pregnancies in Obese Women

Limited data is available that estimates the effect of gestational weight gain on maternal and neonatal outcomes in term twin pregnancies in obese women. A historical cohort study of 831 obese (BMI ≥30.0 kg/m2) women in Missouri delivering 1,662 liveborn, term (≥37 weeks gestation) twin infants in 1998–2005 was conducted. Three gestational weight gain categories were examined: <25 pounds, 25–42 pounds, and >42 pounds. Adjusted odds ratios were calculated with multiple logistic regression, using the 2009 Institute of Medicine provisional guideline of 25–42 pounds as the reference group. Significant increasing trends with gestational weight gain were found for preeclampsia (p < .05), larger twin birth weight (p < .01), smaller twin birth weight (p < .001), and infants weighing >2,500 grams (p < .001). Significant increasing trends for preeclampsia and for cesarean delivery were found in concordant twin pairs (smaller twin >80% of birth weight of larger twin). Women who gained >42 pounds had a borderline significantly higher odds of preeclampsia than women who gained 25–42 pounds (adjusted OR 1.72; 95% CI 1.00–2.99, p = .052). No significant differences were found for 1-min Apgar score <4, 5-min Apgar score <7, or infant mortality ≤1 year. Our study suggests that increasing gestational weight gain is associated with larger infants but increased risk of preeclampsia and cesarean delivery in term twin pregnancies in obese women. Limiting gestational weight gain could reduce the risk of preeclampsia and cesarean delivery. Prospective studies of other study populations and maternal/infant outcomes are needed to evaluate the efficacy of the Institute of Medicine guideline.

Breech presentation at delivery: a marker for congenital anomaly?

OBJECTIVE

To determine whether congenital anomalies are associated with breech presentation at the time of birth.

STUDY DESIGN

A population-based, retrospective cohort study was conducted among 460,147 women with singleton live births using the Missouri Birth Defects Registry, which includes all defects diagnosed during the first year of life. Maternal and obstetric characteristics and outcomes between breech and cephalic presentation groups were compared using χ(2)-square statistic and Student's t-test. Multivariable binary logistic regression analysis was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULT

At least one congenital anomaly was more likely present among infants breech at birth (11.7%) than in those with cephalic presentation (5.1%), whether full-term (9.4 vs 4.6%) or preterm (20.1 vs 11.6%). The relationship between breech presentation and congenital anomaly was stronger among full-term births (aOR 2.09, CI 1.96, 2.23, term vs 1.40, CI 1.26, 1.55, preterm), but not in all categories of anomalies.

CONCLUSION

Breech presentation at delivery is a marker for the presence of congenital anomaly. Infants delivered breech deserve special scrutiny for the presence of malformation.

Fetal head circumference, operative delivery, and fetal outcomes: a multi-ethnic population-based cohort study

BACKGROUND

Operative delivery procedures, such as primary cesarean section, vacuum-assisted, and forceps-assisted vaginal delivery increase maternal and fetal morbidity, and the cost of care. We evaluated whether large fetal head circumference (FHC) independently increases risk of such interventions, as well as fetal distress or low Apgar score, in anatomically normal infants.

METHODS

We conducted a population-based retrospective cohort study using Washington State birth certificate data. We included singleton, term infants born to nulliparous mothers from 2003-2009. We compared mode of delivery and fetal outcomes in 10,750 large-FHC (37-41 cm) infants relative to 10,750 average-FHC (34 cm) infants, frequency matched by birth-year.

RESULTS

Large-FHC infants were nearly twice as likely to be delivered by primary cesarean section as average-FHC infants (unadjusted relative risk [RR] 1.84, 95% confidence interval [CI]: 1.77, 1.92). The RR for primary cesarean section associated with large-FHC was largest for mothers aged 19 years or less (RR 2.28; 95% CI: 1.99, 2.61), and smallest for mothers aged 35 years or greater (RR 1.51; 95% CI: 1.37, 1.66) [test of homogeneity, p < 0.001]. Large-FHC infants were at increased risk of vacuum-assisted vaginal delivery (RR 1.55; 95% CI: 1.43, 1.69), and forceps-assisted vaginal delivery (RR 1.61; 95% CI: 1.32, 1.97). There was no difference in risk of fetal distress (RR 0.97; 95% CI: 0.89, 1.07) for large-FHC versus average-FHC infants. Risk estimates were unaffected by adjustment for potential confounders.

CONCLUSIONS

Nulliparous mothers of large-FHC infants are at increased risk of primary cesarean section, vacuum-assisted and forceps-assisted vaginal delivery relative to mothers of average-FHC infants. Maternal age modifies the association between FHC and primary cesarean section.

History of the birth certificate: from inception to the future of electronic data

Enumerations of people were carried out long before the birth of Jesus. Data related to births were recorded in church registers in England as early as the 1500s. However, not until the 1902 Act of Congress was the Bureau of Census established as a permanent agency to develop birth registration areas and a standard registration system. Although all states had birth records by 1919, the use of the standardized version was not uniformly adopted until the 1930's. In the 1989 US Standard Birth Certificate revision, the format was finally uniformly adopted to include checkboxes to improve data quality and completeness. The evolution of the 12 federal birth certificate revisions is reflected in the growth of the number of items from 33 in 1900 to more than 60 items in the 2003 birth certificate. As birth registration has moved from paper to electronic, the birth certificate's potential utility has broadened, yet issues with updating the electronic format and maintaining quality data continue to evolve. Understanding the birth certificate within its historical context allows for better insight as to how it has been and will continue to be used as an important public-health document shaping medical and public policies.

[Reliability of birth certificates as a source of information on congenital defects in the City of São Carlos, São Paulo, Brazil]

The reliability of the information on congenital defects listed in birth certificates of the Live Birth Information System (SINASC) in the City of São Carlos, São Paulo, Brazil, was evaluated. A descriptive study that reviewed all 15,249 birth certificates from 2003 to 2007 compared the data with information from medical records and death certificates. Errors in accuracy and precision, mainly related to the description of the anomaly when it was transcribed from medical records to the birth certificates, in addition to coding and the input to SINASC, diminished the reliability of the birth certificates as a source of information on congenital defects. The results suggested that the involvement of the Municipal Health Department is essential to improve SINASC, because this is the location of the coding and input system, and training of the professionals who fill out the birth certificates. With guidance on the importance and function of the birth certificates, SINASC can become an excellent monitoring and surveillance system for congenital defects.

Adolescent pregnancy and gestational weight gain: do the Institute of Medicine recommendations apply?

OBJECTIVE

The purpose of this study was to examine the Institute of Medicine (IOM) guidelines for gestational weight gain in adolescents.

STUDY DESIGN

We studied a retrospective cohort using the Missouri Birth Certificate Registry and included subjects who were primiparous, who had singleton gestations, who were <20 years old, and who delivered at 24-44 weeks gestation. The exposure was defined as weight gain less than, within, or greater than IOM recommendations. Outcomes that were examined were small-for-gestational-age (SGA) infants, large-for-gestational age (LGA) infants, preterm delivery, infant death, preeclampsia, cesarean delivery, and operative vaginal delivery. The analysis was stratified by body mass index category.

RESULTS

In any body mass index category, inadequate weight gain was associated with increased odds of SGA infants, preterm delivery, and infant death. When subjects gained more than the IOM recommendations, the number of SGA infants decreased, with slight increases in the number of LGA infants, preeclampsia, and cesarean delivery.

CONCLUSION

Adolescents should be counseled regarding adequate weight gain in pregnancy. Further research is necessary to determine whether the IOM recommendations recommend enough weight gain in adolescents to optimize pregnancy outcomes.

Sensitivity of birth certificate reports of birth defects in Atlanta, 1995-2005: effects of maternal, infant, and hospital characteristics

OBJECTIVES

We assessed variations in the sensitivity of birth defect diagnoses derived from birth certificate data by maternal, infant, and hospital characteristics.

METHODS

We compared birth certificate data for 1995-2005 births in Atlanta with data from the Metropolitan Atlanta Congenital Defects Program (MACDP). We calculated the sensitivity of birth certificates for reporting defects often discernable at birth (e.g., anencephaly, spina bifida, cleft lip, clubfoot, Down syndrome, and rectal atresia or stenosis). We used multivariable logistic regression models to examine associations with sociodemographic and hospital factors.

RESULTS

The overall sensitivity of birth certificates was 23% and ranged from 7% for rectal atresia/stenosis to 69% for anencephaly. Non-Hispanic black maternal race/ethnicity, less than a high school education, and preterm birth were independently associated with a lower probability of a birth defect diagnosis being reported on a birth certificate. Sensitivity also was lower for hospitals with > 1,000 births per year.

CONCLUSIONS

The underreporting of birth defects on birth certificates is influenced by sociodemographic and hospital characteristics. Interpretation of birth defects prevalence estimates derived from birth certificate reports should take these issues into account.

Cesarean and VBAC rates among immigrant vs. native-born women: a retrospective observational study from Taiwan Cesarean delivery and VBAC among immigrant women in Taiwan

BACKGROUND

Cultural and ethnic roots impact women's fertility and delivery preferences This study investigated whether the likelihood of cesarean delivery, primary cesarean, and vaginal delivery after cesarean (VBAC) varies by maternal national origin.

METHODS

We conducted a nation-wide, population-based, observational study using secondary data from Taiwan. De-identified data were obtained on all 392,246 singleton live births (≥500 g; ≥20 weeks) born to native-born Taiwanese, Vietnamese and mainland Chinese-born mothers between January 1, 2006 and December 31, 2007 from Taiwan's nation-wide birth certificate data. Our analytic samples consisted of the following: for overall cesarean likelihood 392,246 births, primary cesarean 336,766 (excluding repeat cesarean and VBAC), and VBAC 55,480 births (excluding primary cesarean and vaginal births without previous cesarean). Our main outcome measures were the odds of cesarean delivery, primary cesarean delivery and VBAC for Vietnamese and Chinese immigrant mothers relative to Taiwanese mothers, using multiple regression analyses to adjust for maternal and neonatal characteristics, paternal age, institutional setting, and major obstetric complications.

RESULTS

Unadjusted overall cesarean, primary cesarean, and VBAC rates were 33.9%, 23.0% and 4.0% for Taiwanese, 27.6%, 20.1% and 5.0% for mainland Chinese, and 19.3%, 13.9 and 6.1% for Vietnamese respectively. Adjusted for confounders, Vietnamese mothers were less likely than native-born Taiwanese to have overall and primary cesarean delivery (OR = 0.59 and 0.58 respectively), followed by Chinese mothers (both ORs = 0.90 relative to native-born Taiwanese). Vietnamese mothers were most likely to have successful VBAC (OR = 1.58), followed by Chinese mothers (OR = 1.25).

CONCLUSION

Immigrant Vietnamese and Chinese mothers have lower odds of cesarean and higher VBAC odds than native-born Taiwanese, consistent with lower cesarean rates prevailing in their home countries (Vietnam 10.1%; mainland China 20%-50% rural and urban respectively).

Qualidade da notificação de anomalias congênitas pelo Sistema de Informações sobre Nascidos Vivos (SINASC): estudo comparativo nos anos 2004 e 2007

Este estudo comparou a validade dos diagnósticos de anomalias congênitas do Sistema de Informações sobre Nascidos Vivos (SINASC), em oito hospitais distribuídos em sete municípios do Brasil, totalizando 27.945 nascidos vivos em 2004 e 25.905 em 2007. Além disso, descreveu ações específicas realizadas para o aprimoramento da qualidade dos dados desse campo. Para a análise da validade, foi utilizado o Estudo Colaborativo Latino-Americano de Malformações Congênitas (ECLAMC) como padrão-ouro. Em 2004, pelo menos 40% dos casos de anomalias congênitas eram subnotificados, situação que não foi modificada em 2007. Observou-se aumento significativo na sensibilidade somente em um hospital, de 56,9% para 96,8%. Em dois hospitais, houve diminuição significativa na sensibilidade, de 62,7% para 41,7% e de 66,5% para 32,2%. Os valores preditivos positivo e negativo e especificidade permaneceram acima de 80%. Apenas duas secretarias municipais de saúde e quatro hospitais fizeram algum tipo de ação específica para a melhoria do campo 34. Os resultados apontam para a necessidade de se investir na qualidade da informação sobre anomalias congênitas no SINASC.

Association of early-onset pre-eclampsia in first pregnancy with normotensive second pregnancy outcomes: a population-based study

OBJECTIVE

To evaluate pregnancy outcomes in normotensive second pregnancy following pre-eclampsia in first pregnancy.

DESIGN

Population-based retrospective cohort study.

SETTING

State of Missouri in the USA.

SAMPLE

White European origin or African-American women who delivered their first two non-anomalous singleton pregnancies between 20 and 44 weeks of gestation in Missouri, USA, 1989-2005, without chronic hypertension, renal disease or diabetes mellitus (n = 12 835).

METHODS

Pre-eclampsia or delivery at 34 weeks of gestation or less in first pregnancy was defined as early-onset pre-eclampsia, whereas late-onset pre-eclampsia was defined as pre-eclampsia with delivery after 34 weeks of gestation. Multivariate regression models were fitted to estimate the crude and adjusted odds ratios and 95% confidence intervals.

MAIN OUTCOME MEASURES

Preterm delivery, large and small-for-gestational-age infant, Apgar scores at 5 minutes, fetal death, caesarean section, placental abruption.

RESULTS

Women with early-onset pre-eclampsia in first pregnancy were more likely to be younger, African-American, recipients of Medicaid, unmarried and smokers. Despite a second normotensive pregnancy, women with early-onset pre-eclampsia in their first pregnancy had greater odds of a small-for-gestational-age infant, preterm birth, fetal death, caesarean section and placental abruption in the second pregnancy, relative to women with late-onset pre-eclampsia, after controlling for confounders. Moreover, maternal ethnic origin modified the association between early-onset pre-eclampsia in the first pregnancy and preterm births in the second pregnancy. Having a history of early-onset pre-eclampsia reduces the odds of having a large-for-gestational-age infant in the second pregnancy.

CONCLUSION

A history of early-onset pre-eclampsia is associated with increased odds of adverse pregnancy outcomes despite a normotensive second pregnancy.

Disparities in cesarean delivery rates and associated adverse neonatal outcomes in New York City hospitals

OBJECTIVE

To examine the primary cesarean delivery rates and associated neonatal outcomes by insurance status in public and private hospitals in New York City.

METHODS

We accessed Vital statistics data on all births to women with Medicaid or private insurance from 1996 through 2003, compiling a total of 321,308 nulliparous women who delivered singleton neonates by either normal spontaneous vaginal delivery or primary cesarean delivery. Rates of primary cesarean delivery and adverse neonatal outcomes were examined by hospital type and insurance status while controlling for potential confounders.

RESULTS

There were 51,682 and 269,626 women who delivered in public hospitals and private hospitals, respectively. The cesarean delivery rate of women with private insurance delivering in private hospitals was 30.4% compared with a cesarean rate of 21.2% in Medicaid patients delivering in public hospitals (adjusted odds ratio [OR] 1.57, 95% confidence interval [CI] 1.53-1.63). The percent of infants born to women with private insurance and Medicaid delivering in private hospitals with a 5-minute Apgar score less than 7 was 0.6% and 0.8% compared with 1.0% of infants delivering in the public hospital system (adjusted OR 0.59, 95% CI 0.51- 0.68 and adjusted OR 0.73, 95% CI 0.65- 0.82). The neonatal intensive care unit admission rate was also lower in neonates born in private hospitals at 6.7% and 8.5% compared with a 12.8% admission rate in public hospitals (adjusted OR 0.48, 95% CI 0.46-0.51 and adjusted OR 0.59, 95% CI 0.57- 0.62 after controlling for mode of delivery).

CONCLUSION

Even when controlling for confounders, there was an association between primary cesarean delivery and insurance status regardless of hospital type. There was also a higher risk of adverse neonatal outcomes in the public hospitals regardless of mode of delivery.

LEVEL OF EVIDENCE

III.

Reviewing performance of birth certificate and hospital discharge data to identify births complicated by maternal diabetes

OBJECTIVES

Public health surveillance of diabetes during pregnancy is needed. Birth certificate and hospital discharge data are population-based, routinely available and economical to obtain and analyze, but their quality has been criticized. It is important to understand the usefulness and limitations of these data sources for surveillance of diabetes during pregnancy.

METHODS

We conducted a comprehensive literature review to summarize the validity of birth certificate and hospital discharge data for identifying diabetes-complicated births.

RESULTS

Sensitivities for birth certificate data identifying prepregnancy diabetes mellitus (PDM) ranged from 47% to 52%, median 50% (kappas: min = 0.210, med = 0.497, max = 0.523). Sensitivities for birth certificate data identifying gestational diabetes mellitus (GDM) ranged from 46% to 83%, median 65% (kappas: min = 0.545, med = 0.667, max = 0.828). Sensitivities for the two studies using hospital discharge data for identifying PDM were 78% and 95% (kappas: 0.839 and 0.964), and for GDM were 71% and 81% (kappas: 0.584 and 0.840). Specificities were consistently above 98% for both data sources.

CONCLUSIONS

Overall, hospital discharge data performed better than birth certificates, marginally so for identifying GDM but substantially so for identifying PDM. Reports based on either source alone should focus on trends and disparities and include the caveat that results under represent the problem. Linking the two data sources may improve identification of both GDM and PDM cases.

Recurrence of preeclampsia: effects of gestational age at delivery of the first pregnancy, body mass index, paternity, and interval between births

OBJECTIVES

The purpose of this study was to establish estimates for recurrence risk of preeclampsia based on gestational age at delivery of the first pregnancy complicated by preeclampsia and to determine whether interbirth interval, paternity, and body mass index (BMI) modify that risk in women with prior preeclampsia.

STUDY DESIGN

A population-based, cohort study was conducted using data from Missouri maternally linked birth certificates. The cohort included women who had 2 singleton births between 1989 and 1997: 6157 women with preeclampsia and 97,703 women without preeclampsia at the time of their first deliveries. Data were analyzed using the Poisson regression.

RESULTS

At the time of their second delivery, 14.7% women with prior preeclampsia developed recurrent preeclampsia. The risk of recurrent preeclampsia is inversely related to gestational age at the first delivery: 38.6% for 28 weeks' gestation or earlier, 29.1% for 29-32 weeks, 21.9% for 33-36 weeks, and 12.9% for 37 weeks or more. The recurrent preeclampsia risk was fairly constant if both births occurred within 7 years. Obese and overweight women had higher risks of recurrent preeclampsia (19.3% and 14.2%), compared with women with normal BMI (11.2%). The recurrence risk did not differ according to paternity status.

CONCLUSION

The risk of preeclampsia recurrence increases with earlier gestational age at the first delivery complicated by preeclampsia and with increasing maternal BMI.

A Comparison of Breastfeeding Rates in an Urban Birth Cohort Among Women Delivering Infants at Hospitals That Employ and Do Not Employ Lactation Consultants

OBJECTIVE

To compare rates of breastfeeding at hospital discharge between facilities that employ and do not employ International Board Certified Lactation Consultants (IBCLCs).

METHODS

This study used a cross-sectional design. Data from 11,525 birth certificates of Philadelphia residents who delivered in 2003 were used. Breastfeeding was assessed using a question included on the Pennsylvania birth record, "Is the infant being breastfed at discharge?" The Philadelphia Department of Public Health's lactation consultants collected information on number of hours worked annually by IBCLCs by facility.

RESULTS

After adjusting for race/ethnicity, education, insurance status, age, marital status, route of delivery, birth weight, and gestational age, delivering in a hospital that employed an IBCLC was associated with a 2.28 (95% confidence interval [CI] =1.98,2.62) times increase in the odds of breastfeeding at hospital discharge. Among women receiving Medicaid, delivering at a hospital that employed IBCLCs was associated with a 4.13 (95% CI =3.22,4.80) times increase in the odds of breastfeeding at hospital discharge.

CONCLUSIONS

The findings presented here identify an association between delivering at a facility that employs IBCLCs and breastfeeding at hospital discharge. As the strength of this association is not negligible, particularly for women on Medicaid, these findings may be used to encourage widespread use of IBCLCs.

Cesarean section in term breech presentations: do rates of adverse neonatal outcomes differ by hospital birth volume?

AIM

To determine if risk of adverse neonatal outcomes among term breech infants delivered by cesarean section differs by volume of such births at the delivering hospital.

METHODS

We conducted a population-based cohort study using Missouri linked birth and death certificate files. The study population included 10,106 singleton, term, normal birth weight infants in breech presentation delivered by cesarean section. Infants were linked to hospitals where delivered. These hospitals were divided into terciles (low, medium, and high volume) based on the median number of annual deliveries during 1993-1999. The primary outcome was presentation of at least one adverse neonatal outcome. Adjusted odds ratios and 95% confidence intervals (CI) were calculated using logistic regression analysis.

RESULTS

The rate of any adverse outcome was 17.8, 15.0, and 5.9 cases per 1,000 deliveries at low-, medium-, and high-volume hospitals, respectively. All component adverse outcomes occurred more frequently in low- or medium-volume hospitals than in high-volume hospitals. Compared to breech infants delivered at high-volume hospitals, those delivered at low-volume and medium-volume hospitals were 2.7 (CI 1.6, 4.5) and 2.4 (CI 1.4, 4.1) times, respectively, more likely to experience an adverse outcome after adjusting for significant confounders.

CONCLUSIONS

Prospective studies should explore the source of these risk differences.

Maternal and birth characteristics in relation to childhood leukaemia

Our objective was to investigate the association of childhood leukaemia with selected maternal and birth characteristics by conducting a population-based case-control study using linked cancer registry and birth certificate records for Washington State. We compared maternal and infant characteristics of 595 Washington-born residents <20 years old with leukaemia diagnosed during 1981-2003, and 5,950 control children, using stratified analysis and logistic regression. Maternal age 35+ years (odds ratio [OR] 1.5; 95% confidence interval [CI] 1.1, 2.0), infant birthweight 4,000+ g (OR 1.4; 95% CI 1.1, 1.8), neonatal jaundice (OR 1.5; 95% CI 1.1, 2.1), and Down's syndrome (OR 31.3; 95% CI 6.4, 153.4) were associated with an increased risk of leukaemia. Among women with 2+ pregnancies, having at least two prior early (<20 weeks' gestation) fetal deaths was also associated with an increased risk (OR 1.5; 95% CI 0.97, 2.1). Maternal unmarried status (OR 0.7; 95% CI 0.6, 0.9) and African American race (OR 0.5; 95% CI 0.3, 0.9) were associated with a decreased risk. These results were more marked for acute lymphocytic leukaemia (ALL) than for acute myeloid leukaemia (AML), and for leukaemia diagnosed <5 years of age. These results may provide clues to the aetiology of childhood leukaemia. Genetic epidemiological studies are needed to expand our knowledge of inherent and possibly prenatal influences on the occurrence of this disease.

Trends and racial/ethnic disparities in gestational diabetes among pregnant women in New York City, 1990-2001

We analyzed gestational diabetes mellitus trends in New York City between 1990 and 2001 by using information obtained from birth certificates. Gestational diabetes diagnoses among women who delivered babies increased 46%, from 2.6% (95% confidence interval [CI]=2.5, 2.7) to 3.8% (95% CI=3.7, 3.9) of births. Prevalence was highest among South and Central Asian women (11%). Given risks for adverse fetal outcomes and maternal chronic diabetes, prompt screening is critical. Metabolic control should be maintained during pregnancy and assessed postpartum for women with gestational diabetes.

Tertiary care improves the chance for vaginal delivery in women with preeclampsia

OBJECTIVE

The purpose of this study was to determine whether the level of hospital care affects cesarean delivery rates for women with preeclampsia.

STUDY DESIGN

We conducted a population-based cohort study using Missouri birth certificate data for 1993 through 1999. Logistic regression was used to analyze data from 13,646 nulliparous women with preeclampsia who were delivered of singleton live births.

RESULTS

After adjustment was made for gestational age and birth weight, the data showed that women with preeclampsia at primary and secondary hospitals were more likely to be delivered by cesarean delivery (odds ratio, 1.37; 95% CI, 1.24,1.51; and odds ratio, 1.16; 95% CI, 1.07,1.26, respectively) than at tertiary hospitals. For women who were delivered at >or=37 weeks of gestation, cesarean delivery rates were 38.0%, 33.7%, and 30.0% for primary, secondary, and tertiary hospitals, respectively. Dysfunctional labor, cephalopelvic disproportion, and fetal distress were more commonly noted at primary and secondary hospitals (P<.001).

CONCLUSION

Levels of expertise and staffing at tertiary hospitals may allow greater attempts and success with vaginal delivery among women with preeclampsia compared with primary or secondary hospitals.

Preeclampsia in the parous woman: who is at risk?

OBJECTIVE

The purpose of this study was to identify risk factors for preeclampsia in second pregnancies and to determine whether gestational age at delivery in the first pregnancy increases the risk of recurrent preeclampsia.

STUDY DESIGN

We conducted a population-based, case-control study using birth certificate data from the Missouri maternally linked cohort. Data from women delivered of their first 2 singleton pregnancies between 1989 and 1997 (2332 cases with preeclampsia in the second pregnancy and 2370 control cases) were analyzed with logistic regression.

RESULTS

Significant risk factors for preeclampsia in a second pregnancy include longer birth interval, previous preterm delivery, previous small-for-gestational-age newborn, renal disease, chronic hypertension, diabetes mellitus, obesity, black race, and inadequate prenatal care. Smoking and same paternity are protective. A history of preeclampsia confers the highest risk for preeclampsia in the second pregnancy; the risk is inversely proportional to gestational age at delivery of the first pregnancy: adjusted odds ratio, 15.0; 95% CI, 6.3-35.4 for 20 to 33 weeks; adjusted odds ratio, 10.2; 95% CI, 6.2-17.0 for 33 to 36 weeks; and adjusted odds ratio, 7.9; 95% CI, 6.3-10.0 for 37 to 45 weeks.

CONCLUSION

The relative risk of recurrent preeclampsia increases with earlier gestational age at delivery of the first pregnancy that was complicated by preeclampsia.

Outcomes of infants born to mothers with inflammatory bowel disease: a population-based cohort study

OBJECTIVE

Limited population-based data on inflammatory bowel disease (IBD) and pregnancy outcomes exist. The purpose of this study is to determine the association between maternal IBD status and adverse pregnancy outcomes.

METHODS

Using computerized birth records of infants born to mothers with Crohn's disease (CD) or ulcerative colitis (UC) and mothers without diagnoses of IBD (no-IBD) in Washington State, we performed a cross-sectional retrospective study to determine gestational age, birth weight, and congenital malformations.

RESULTS

Preterm delivery was seen in 15.2% of CD births, 10.4% of UC births, and 7.2% of no-IBD births. Low birth weight was found in 16.8% of CD births, 7.6% of UC births, and 5.3% of no-IBD births. Smallness for gestational age was present in 15.2% of CD births, 10.5% of UC births, and 6.9% of no-IBD births. Only CD births were at significantly increased risk of preterm delivery (p < 0.0025), low birth weight (p < 0.001), and smallness for gestational age (p < 0.001). Congenital malformations were more commonly recorded in UC births than in controls (7.9% vs 1.7%, p < 0.001), whereas 3.4% of CD births had malformations recorded. Using multivariable logistic regression, CD births were more likely to be preterm (odds ratio [OR] = 2.3, 95% CI = 1.4-3.8) and have low birth weights (OR = 3.6, CI = 2.2-5.9) and smallness for gestational age (OR = 2.3, CI = 1.3-3.9). UC births were more likely to have congenital malformations reported (OR = 3.8, CI = 1.5-9.8).

CONCLUSIONS

Maternal IBD is associated with increased odds of preterm delivery, low birth weight, smallness for gestational age (CD), and reporting of congenital malformations (UC).

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.

Pregnancy complications and outcomes among overweight and obese nulliparous women

OBJECTIVES

This study examined the associations between prepregnancy weight and the risk of pregnancy complications and adverse outcomes among nulliparous women.

METHODS

We conducted a population-based cohort study with 96,801 Washington State birth certificates from 1992 to 1996. Women were categorized by body mass index. Multivariate logistic regression was performed.

RESULTS

The rate of occurrence of most of the outcomes increased with increasing body mass index category. Compared with lean women, both overweight and obese women had a significantly increased risk for gestational diabetes, preeclampsia, eclampsia, cesarean delivery, and delivery of a macrosomic infant.

CONCLUSIONS

Among nulliparous women, not only prepregnancy obesity but also overweight increases the risk of pregnancy complications and adverse pregnancy outcomes.

How well do birth certificates describe the pregnancies they report? The Washington State experience with low-risk pregnancies

OBJECTIVES

Birth certificates are a major source of population-based data on maternal and perinatal health, but their value depends on the accuracy of the data. This study assesses the validity of information recorded on the birth certificates for women in Washington State who were considered to be low risk at entry into care.

METHODS

Birth certificates were matched to data abstracted from prenatal and intrapartum clinic and hospital records of a sample of 1937 Washington State obstetrical patients who were considered to be low risk at the beginning of their pregnancies. Accuracy of a variety of pregnancy characteristics (e.g., complications, procedures) on the birth certificate was analyzed using percentage agreement and sensitivity with record abstracts as the "gold standard." Next, we weighted the data from each source to produce estimates of pregnancy characteristics in the population. We compared these estimates from the two data sources to see whether they provide similar pictures of this subpopulation.

RESULTS

Missing data for specific items on the birth certificates ranged from 0% to 24%. The birth certificate accurately captured gravidity and parity, but was less likely to report prenatal and intrapartum complications. The population estimates of the two data sources were significantly different.

CONCLUSIONS

Because birth certificates significantly underestimated the complications of pregnancies, number of interventions, number of procedures, and prenatal visits, use of these data for health policy development or resource allocation should be tempered with caution.

Validity of insurance information on California birth certificates

OBJECTIVES

This study assessed the validity of health insurance information on California birth certificates.

METHODS

Insurance information from birth certificates and linked face-to-face interviews was compared for 7428 postpartum women in California.

RESULTS

There was excellent agreement between insurance information in birth certificate and interview data, especially when capitated plans were grouped with all other private coverage. Analyses using both data sources produced similar estimates of the likelihood of untimely prenatal care according to type of insurance coverage.

CONCLUSIONS

Birth certificate data including insurance information appear to be an appropriate resource for examining both the extent of coverage for maternity care and associations between prenatal care use and insurance status.

The surveillance of birth defects: the usefulness of the revised US standard birth certificate

To assess the sensitivity and positive predictive value of birth defects reported on the 1989 revision of the US Standard Birth Certificate, a population of 76,862 Atlanta-area births during 1989 and 1990 was used as the basis for comparing 771 birth certificates that reported birth defects with 2428 live-born infant records in a birth defects registry that uses multiple sources of case ascertainment. Only 14% of birth defects in the registry records were reported on birth certificates. After the analysis was restricted to defects recognizable at birth, the sensitivity and positive predictive value of the birth certificates were 28% and 77%, respectively. Birth certificates underestimate birth defect rates and should be used cautiously for birth defect surveillance and epidemiological studies.

Case ascertainment for state-based birth defects registries: characteristics of unreported infants ascertained through birth certificates and their impact on registry statistics in New York state

Cases in the New York State Congenital Malformations Registry are reported by hospitals and physicians. This study was undertaken to determine whether case finding should be expanded to include routine matching of Vital Records files to the registry in order to identify unreported children. Matching of children who were born in 1983-86 and who had a congenital malformation noted on their birth certificate yielded 2837 children who were not in the registry. The hospital of record was asked to submit a registry report if the child's medical record contained a congenital malformation. Medical records for 1267 (45%) of these children indicated that the child was normal, with no mention of a malformation. Medical records could not be located for 137. Registry reports were submitted for 1433, 67 of whom were subsequently found in the registry, leaving 1366 bona fide new cases. These new cases differ significantly from registry cases for a number of birth certificate variables and type of congenital malformation. The birth certificate cases were more likely than registry cases to have only one malformation and to have only a minor malformation. The 1366 new cases comprised 2.1% of all registry cases for 1983-86. Their addition increased the statewide prevalence of major malformations by 1.7% from 416.5 to 423.4 per 10 000 livebirths. Except for anencephaly, the prevalence of specific malformations was not altered measurably by the addition of these cases. Lengthy and continuous follow-up was required to obtain registry reports. The small number of cases found does not seem to justify the amount of resources that would be required to use birth certificates routinely to augment case finding in New York State.

Why is the cesarean delivery rate so high in Alabama? An examination of risk factors, 1991-1993

BACKGROUND

Cesarean delivery is now the most frequently performed major operative procedure for childbearing women in the United States. Many of these operations are reported to be unnecessary, and millions of dollars could be saved by reducing their frequency.

METHODS

Method of delivery was added to the 1989 revision of the standard certificate of live birth. Alabama also added questions on the source of payment for delivery and the provider of prenatal care in 1991, which enabled an investigation of the risk factors for cesarean delivery that occurred in the state during this period.

RESULTS

One of every four births in Alabama is by cesarean delivery. The risk of cesarean delivery is not random, and the risk factors include mother's race and age, coverage by private insurance, birthweight, setting where the mother received prenatal care, mother's educational attainment, live birth order, and complications of labor and delivery.

CONCLUSION

With present concerns about health care reform and the costs of health care, a reduction in the cesarean delivery rate could result in significant cost savings.

A population-based case-control study of risk factors for breech presentation

OBJECTIVE

We evaluated relationships between breech presentation and infant, maternal, and pregnancy characteristics of singleton births.

STUDY DESIGN

A population-based case-control study (3588 breech cases, 8183 controls) was conducted with data from the 1987 to 1988 Washington State birth certificate.

RESULTS

Low birth weight, short gestational age, primiparity, and older maternal age were associated with increased risk of breech birth, and after we controlled for these factors, the following were also associated with breech birth: hydrocephalus, established maternal diabetes, congenital malformation of the infant, smoking during pregnancy, and late or no prenatal care. In addition, black and Filipino women had decreased risk of breech presentation compared with white women.

CONCLUSION

Several different maternal and infant characteristics appear to increase risk of breech birth, suggesting that there may be several different biologic mechanisms leading to breech presentation.

The risk of diabetes in a subsequent pregnancy associated with prior history of gestational diabetes or macrosomic infant

Prior studies suggest that diagnosis of gestational diabetes is associated with increased risk for development of gestational diabetes in future pregnancies, and with subsequent onset of established diabetes. The magnitudes of these risks have not been measured. Using linked birth certificate data from Washington State it is possible to identify all women with two or more births occurring during 1984-91. All women with gestational diabetes (n=1375) or with established diabetes (n=220), during their pregnancy for the second or greater birth were identified, and a control group consisting of women whose second or greater birth was not complicated by either condition was randomly selected (n=6380). Data from the birth certificate, for the previous birth, were compared in order to estimate the risks of developing gestational or established diabetes in a subsequent pregnancy among women with prior gestational diabetes relative to women without gestational diabetes. The age-adjusted risk of developing gestational diabetes in the pregnancy for the subsequent birth associated with prior gestational diabetes was 23.2 (95% (confidence interval) CI = 17.2-31.2); the risk of having developed established diabetes by the time of the subsequent birth was 55.5 (95% CI = 34.4-89.4). Women who had a macrosomic infant (>4000 gm) in the prior birth were also at increased risk for developing gestational diabetes (odds ratio OR = 3.3, 95% CI = 2.9-3.8) or established diabetes (OR = 5.8, 95% CI = 4.0-8.5). When data were restricted to patients with only one prior birth, to patients with early prenatal care, to delivery at facilities with long-established protocols for diagnosing gestational diabetes, or to more recent years, the risk estimates remained similarly elevated. The 23-fold increased risk of gestational diabetes associated with having gestational diabetes indicated on the birth certificate of a woman's previous baby, although not unexpected, is still remarkable and reinforces the importance of careful monitoring of women with this history. Although changes in how screening is conducted may account for some of the elevation in risk, our results stayed consistently elevated even when restrictions were made within the data to control for this. The fact that there was a 56-fold increased risk of having developed established diabetes by the time of the subsequent birth on record, associated with prior gestational diabetes, and a 6-fold increased risk associated with a macrosomic infant, supports the idea that these may be early steps in the development of established diabetes, and identifies a group that may benefit from close monitoring and possible intervention.

Epidemiology of eclampsia

The purpose of this study was to examine the risk of eclampsia in relation to several maternal characteristics and exposures, including demographic characteristics, reproductive history, and tobacco use during pregnancy. A case control study was conducted using data for all singleton births from the Washington State birth certificates for 1984-1990. In the check box feature employed by these certificates, eclampsia is listed under maternal conditions. Risk estimates, adjusted for various confounders, were calculated comparing eclampsia among exposed versus unexposed women. The risk of eclampsia was elevated in women without prenatal care, those with weight gain of more than thirty pounds during pregnancy, nulliparous women, and those with chronic hypertension. The association with tobacco smoking were inverse and dose related. Women's race, urban or rural place of residence, history of pre-term births, and anemia were not associated with eclampsia. Our data reaffirm the importance of prenatal care, and provide further evidence of an inverse relationship with prenatal smoking. As eclampsia and pre-eclampsia are important pregnancy complications, further research is needed to explore their possible causes.

Racial/ethnic differences in the likelihood of cesarean delivery, California

OBJECTIVES

The purpose of this study was to determine whether women's sociodemographic characteristics are independently associated with cesarean delivery.

METHODS

A retrospective review was conducted of hospital discharge data for singleton first births in California in 1991.

RESULTS

After insurance and personal, community, medical, and hospital characteristics had been controlled, Blacks were 24% more likely to undergo cesarean delivery than Whites; only among low-birthweight and county hospital births were Blacks not at a significantly elevated risk. Among women who resided in substantially non-English-speaking communities, who delivered high-birthweight babies, or who gave birth at for-profit hospitals, cesarean delivery appeared to be more likely among non-Whites and was over 40% more likely among Blacks than among Whites.

CONCLUSIONS

The findings cannot establish causation, but the significant racial/ethnic disparities in delivery mode, despite adjustment for social, economic, medical, and hospital factors, suggest inappropriate influences on clinical decision making that would not be addressed by changes in reimbursement. If practice variations among providers are involved, de facto racial differences in access to optimal care may be indicated. The role of provider and patient attitudes and expectations in the observed racial/ethnic differentials should also be explored.

Data quality after restructuring a national medical registry

The validity of the 1991 Finnish Medical Birth Registry data was assessed, with special emphasis on the effects of changes made to the data collection form in 1990. Data abstracted from medical records for all births occurring in 49 hospitals during a five-day sample period (n = 865) were compared to the register information. Good or satisfactory validity was found for 32 of 33 variables, when minor error was tolerated in variables with continuous scales. For diagnoses and procedures, recorded in check-box format, satisfactory validity was found for 10 of 45 variables. Validity could not be assessed for 18 variables because of insufficient number of cases (13 items) or definition problems (5 items). When the results were compared to a 1987 data quality study, many of the variables that had been changed to the check-box format showed improvement in validity. In addition, in some cases a small change in question alternatives or instructions caused a noticeable change in validity.

A quality study of a computerized medical birth registry

Processed by a computerized medical birth registry system, the birth records of 20,103 deliveries, from February 1992 to February 1993, were digitized with medium registry. From January 1, to February 28, 1993, the original records (n = 2,840 cases) of all 10 collaborative hospitals were requested for assessment of the data quality. Thirty-six items were scored, data of poor quality was found in 8 items; acceptable quality in 4 items; and good quality in 28 items. The feasibility of data transfer by floppy disc and per modem was evaluated. This registry system had shortened data processing time effectively and improved mutual feedback between data center and delivery units. Errors resulting from technical faults originating in preparation of the data for computerizing at hospital level could be effectively reduced. The validity of diagnosis remained as the major source of errors.

Reproductive history and the risk of neonatal sepsis

It was recently suggested that a previous abortion increases the risk of intrapartum infection in a following pregnancy. The authors hypothesised that abortion also could be associated with a higher risk of neonatal sepsis. A case-control study of neonatal sepsis was conducted using the Washington State Birth Registry. Cases of sepsis were selected among singleton livebirths during the period 1984-90, and compared with a control group for the occurrence of spontaneous or induced abortion in previous pregnancies. The risk estimates were calculated using a stratified analysis. After exclusion of primigravidae, the age-adjusted odds ratio (OR) was 1.68, with a 95% confidence interval (CI) 1.33, 2.11 for previous spontaneous abortion, and 2.20 (95% CI 1.73, 2.79) for induced abortion, compared with previous livebirth. After exclusion of nulliparous women, the OR decreased to 1.19 (95% CI 0.90, 1.58) for spontaneous abortion and 1.45 (95% CI 1.03, 2.04) for induced abortion. After controlling for the effect of parity, induced abortion is associated with an increased risk of neonatal sepsis in a subsequent pregnancy, but the association between spontaneous abortion and sepsis is small and non-significant. The authors suggest that the procedures involved in a therapeutic abortion might produce a latent, sub-clinical infection that persists until the next pregnancy, and is then transmitted to the newborn.

The revised standard certificate of live birth: analysis of medical risk factor data from birth certificates in Alabama, 1988-92

The latest revision of the birth certificate features a new checkbox format designed to collect more effectively information for public health research. One of the new checkbox items, medical risk factors for this pregnancy, is designed to collect information on risk factors which result in adverse pregnancy outcomes. Data from 308,573 birth certificates filed in Alabama between 1988 and 1992 were analyzed. Although problems exist with the data collected for this item, useful information can be obtained to investigate important public health issues. First, the data can be used to determine the prevalence of medical risk factors in the population. Second, differences between subpopulations with these conditions can be examined. For example, some differences between racial groups in adverse pregnancy outcomes may be explained by the fact that black mothers are more likely to have a medical risk factor than whites. Third, some medical factors are associated with elevated risks for low birth weight, while others are associated with reduced probability of low birth weight. Although useful data can be obtained from the medical risk factor item, it and other checkbox items would be more useful if efforts were made to improve reporting. Improvements in training persons who complete the birth certificate are especially needed. Reporting of checkbox items also needs to be validated by comparing results with other sources. In future revisions of the birth certificate, new items need to be examined carefully to determine if that instrument is the appropriate medium for collecting the information.

Zygosity as a risk factor for complications and outcomes of twin pregnancy

All of the recorded twin live births in Washington State birth certificates between 1984 and 1988 were used a retrospective cohort study to determine the risk of zygosity on pregnancy complications and birth outcomes (n = 3458). Relative risks comparing different sex (DS) twins to same sex (SS) twins were corrected to relative risks relating dizygotic (DZ) to monozygotic (MZ) twins, using the Weinberg rule. A higher proportion of DS twin pregnancies (3.5%) than SS pregnancies (1.6%) were complicated by gestational diabetes, resulting in an estimated risk for DZ twin pregnancies relative to MZ pregnancies of 8.6 (95% CI = 3.5-21.0). DZ twin pregnancies were at a lower risk for complications of polyhydraminios (RRDZ/MZ = 0.2, 95% CI = 0.1-0.4) and of pyelonephritis, (RRDZ/MZ = 0.3, 95% CI = 0.1-0.8). MZ twins were more likely to have low birthweight and to have shorter gestations. The proportion of first-born babies of MZ twin pairs who died during their first year was similar to that of first twins of DZ pairs; however, the second-born of MZ twins were more likely to die in infancy than were second-born DZ pairs. First twins of DZ pairs were more likely to die of SIDS (sudden infant death syndrome) than the first of MZ twins (RRDZ/MZ = 1.5, 95% CI = 0.4-5.1). In contrast, DZ second-born were less likely to die of SIDS than were MZ second-born twins (RRDZ/MZ = 0.1, 95% CI = 0.1-0.7). DZ twins were less likely to have adverse newborn conditions or malformations. The high risk for gestational diabetes for DZ twin mothers is possibly due to the presence of two placentas which may support the development of greater insulin antagonism than the single placenta in the mother of MZ twins. The reduced risk of DZ relative to MZ twins for selected adverse birth outcomes may result from the increased tendency of MZ twins to be premature.

Data quality of a computerized medical birth registry

Processed by a computerized medical birth registry system, the birth records of 20,103 deliveries, from February 1992 to February 1993, were digitized with medium registry. From 1 January to 28 February 1993, the original records (n = 2840 cases) of all 10 collaborative hospitals were requested for assessment of data quality. Thirty-six items were scored, data of poor quality was found in eight; acceptable quality in four; and good quality in 28. The feasibility of data transfer by floppy disc and per modem was evaluated. This registry system had effectively shortened data processing time and improved mutual feedback between the data centre and the delivery units. Errors resulting from technical faults originating in the preparation of data for computerization at hospital level could be effectively reduced. The validity of diagnosis remained as the major source of errors.