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Biomedical subjects

K S Joseph

Publications and source records attributed to K S Joseph.

At least 19 recordsLinked to original sources
PubMed2006

Increasing prevalence of cerebral palsy among very preterm infants: a population-based study.

OBJECTIVES: It is unclear whether declines in neonatal and infant mortality have led to changes in the occurrence of cerebral palsy. We conducted a study to examine and investigate recent temporal changes in the prevalence of cerebral palsy in a population-based cohort of very preterm infants who were 24 to 30 weeks of gestational age. METHODS: A population-based cohort of very preterm infants who were born between January 1, 1993, and December 31, 2002, was evaluated by the Perinatal Follow-up Program of Nova Scotia. Follow-up extended to age 2 years to ascertain the presence or absence of cerebral palsy and for overall survival. Infant survival and cerebral palsy rates were compared by year and also in two 5-year periods, 1993-1997 and 1998-2002. Logistic regression analyses were used to identify factors that potentially were responsible for temporal changes in cerebral palsy rates. RESULTS: A total of 672 liveborn very preterm infants were born to mothers who resided in Nova Scotia between 1993 and 2002. Infant mortality among very preterm infants decreased from 256 per 1000 live births in 1993 to 114 per 1000 live births in 2002, whereas the cerebral palsy rates increased from 44.4 per 1000 live births in 1993 to 100.0 per 1000 live births in 2002. Low gestational age, postnatal dexamethasone use, patent ductus arteriosus, severe hyaline membrane disease, resuscitation in the delivery room, and intraventricular hemorrhage were associated with higher rates of cerebral palsy, whereas antenatal corticosteroid use was associated with a lower rate. CONCLUSION: Cerebral palsy has increased substantially among very preterm infants in association with and possibly as a consequence of large declines in infant mortality.

Cerebral Palsy↗
PubMed2006

Amniotic-fluid embolism and medical induction of labour: a retrospective, population-based cohort study.

BACKGROUND: Amniotic-fluid embolism is a rare, but serious and often fatal maternal complication of delivery, of which the cause is unknown. We undertook an epidemiological study to investigate the association between amniotic-fluid embolism and medical induction of labour. METHODS: We used a population-based cohort of 3 million hospital deliveries in Canada between 1991 and 2002 to assess the associations between overall and fatal rates of amniotic-fluid embolism and medical and surgical induction, maternal age, fetal presentation, mode of delivery, and pregnancy and labour complications. FINDINGS: Total rate of amniotic-fluid embolism was 14.8 per 100,000 multiple-birth deliveries and 6.0 per 100,000 singleton deliveries (odds ratio 2.5 [95% CI 0.9-6.2]). Of the 180 cases of amniotic-fluid embolism in women with singleton deliveries during the study period, 24 (13%) were fatal. We saw no significant temporal increase in occurrence of amniotic-fluid embolism for total or fatal cases. Medical induction of labour nearly doubled the risk of overall cases of amniotic-fluid embolism (adjusted odds ratio 1.8 [1.3-2.7]), and the association was stronger for fatal cases (crude odds ratio 3.5 [1.5-8.4]). Maternal age of 35 years or older, caesarean or instrumental vaginal delivery, polyhydramnios, cervical laceration or uterine rupture, placenta previa or abruption, eclampsia, and fetal distress were also associated with an increased risk. INTERPRETATION: Medical induction of labour seems to increase the risk of amniotic-fluid embolism. Although the absolute excess risk is low, women and physicians should be aware of this risk when making decisions about elective labour induction.

Adult↗
PubMed2006

US Black vs White disparities in foetal growth: physiological or pathological?

BACKGROUND: Birthweight for gestational age is lower in US Black infants than in US White infants. It is unknown, however, whether this difference is 'normal' (i.e. physiological) or reflects pathological foetal growth restriction. METHODS: We applied an analytic approach based on foetuses at risk to compare gestational age-specific rates of live birth, 'revealed' small-for-gestational-age (SGA), and neonatal mortality among singleton infants >or=22 weeks of gestation and >or=500 g born in 1998-2000 to US White (n = 9 012 194), US-born Black (n = 1 554 382), and foreign-born Black (n = 200 395) mothers. Graphical methods and Cox proportional hazards regression analyses were used to compare outcomes in the three ethnic groups. RESULTS: Rates of live birth and neonatal mortality were highest at all gestational ages in US-born Blacks, lowest in Whites, and intermediate in foreign-born Blacks. The revealed SGA pattern cohered much more closely with the observed pattern for neonatal mortality when SGA was defined based on a single, overall standard of birthweight for gestational age than when based on ethnic group-specific standards. CONCLUSION: The closer coherence of revealed SGA and neonatal mortality rates based on a single standard and the intermediate pattern among foreign-born Blacks strongly suggest that Black-White differences in birthweight for gestational age are pathological, rather than physiological.

Adult↗
PubMed2006

Study protocol: a double blind placebo controlled trial examining the effect of domperidone on the composition of breast milk [NCT00308334].

BACKGROUND: Domperidone, a drug that enhances upper gastric motility, is an anti-dopaminergic medication that also elevates prolactin levels. It has been shown to safely increase the milk supply of lactating women. To date, researchers have analyzed the effects of domperidone on lactating woman with respect to the quantity of their milk production, adverse effects, and drug levels in the breast milk. However, the effect of domperidone on the macronutrient composition of breast milk has not been studied and current guidelines for fortification of human milk for premature infants do not distinguish between those women using or those not using domperidone. The purpose of this study is to evaluate the effect of domperidone (given to lactating mothers of very preterm infants) on the macronutrient composition of breast milk. METHODS/DESIGN: Mothers of infants delivered at less than 31 weeks gestation, who are at least 3 weeks postpartum, and experiencing lactational failure despite non-pharmacological interventions, will be randomized to receive domperidone (10 mg three times daily) or placebo for a 14-day period. Breast milk samples will be obtained the day prior to beginning treatment and on days 4, 7 and 14. The macronutrient (protein, fat, carbohydrate and energy) and macromineral content (calcium, phosphorus and sodium) will be analyzed and compared between the two groups. Additional outcome measures will include milk volumes, serum prolactin levels (measured on days 0, 4, and 10), daily infant weights and breastfeeding rates at 2 weeks post study completion and at discharge. Forty-four participants will be recruited into the study. Analysis will be carried out using the intention to treat approach. DISCUSSION: If domperidone causes significant changes to the nutrient content of breast milk, an alteration in feeding practices for preterm infants may need to be made in order to optimize growth, nutrition and neurodevelopment outcomes.

Journal Article↗
PubMed2006

Risk factors for hyperemesis gravidarum requiring hospital admission during pregnancy.

OBJECTIVE: To identify risk factors for hyperemesis requiring hospital admission during pregnancy. METHODS: Data from a population-based cohort of all deliveries in Nova Scotia, Canada between 1988 and 2002 were obtained from the Nova Scotia Atlee Perinatal Database. Women with 1 or more antepartum admissions for hyperemesis were compared with women with no admissions for hyperemesis. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using logistic regression and used to determine a set of independent risk factors for hyperemesis. RESULTS: The overall rate of admission for hyperemesis was 0.8% (n = 1,301) among 157,922 deliveries. In the adjusted analysis, hyperthyroid disorders (RR 4.5, 95% CI 1.8-11.1), psychiatric illness (RR 4.1, 95% CI 3.0-5.7), previous molar pregnancy (RR 3.3, 95% CI 1.6-6.8), preexisting diabetes (RR 2.6, 95% CI 1.5-4.7), gastrointestinal disorders (RR 2.5, 95% CI 1.8-3.6), and asthma (RR 1.5, 95% CI 1.2-1.9) were all statistically significant risk factors for hyperemesis, whereas maternal smoking and maternal age older than 30 were associated with decreased risk. Compared with singleton male pregnancies, singleton female pregnancies, pregnancies with multiple male fetuses, and male and female combinations were associated with statistically significant increased risk of hyperemesis. CONCLUSION: Although hospitalization for hyperemesis occurs in less than 1% of pregnant women, this translates to a large number of hospital admissions. The factors associated with hyperemesis are primarily medical and fetal factors that are not easily modifiable, but identification of these factors may be useful in determining those women at high risk for developing hyperemesis. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2006

Outcomes of pregnancies complicated by hyperemesis gravidarum.

OBJECTIVE: To evaluate maternal and neonatal outcomes among women with hyperemesis during pregnancy. METHODS: A population-based retrospective cohort study was conducted among women with singleton deliveries between 1988 and 2002. Hyperemetic pregnancies were defined as those requiring one or more antepartum admissions for hyperemesis before 24 weeks of gestation. Severity of hyperemesis was evaluated according to the number of antenatal hospital admissions (1 or 2 versus 3 or more) and according to weight gain during pregnancy (< 7 kg [15.4 lb] versus > or = 7 kg). Maternal outcomes evaluated included weight gain during pregnancy, gestational diabetes, gestational hypertension, labor induction, and cesarean delivery. Neonatal outcomes included 5-minute Apgar score of less than 7, low birth weight, small for gestational age, preterm delivery, and perinatal death. Logistic regression was used to generate adjusted odds ratios for all outcomes, and the odds ratios were converted to relative risks. RESULTS: Of the 156,091 singleton pregnancies, 1,270 had an admission for hyperemesis. Compared to women without hyperemesis, infants born to women with hyperemesis and with low pregnancy weight gain (< 7 kg [15.4 lb]) were more likely to be low birth weight, small for gestational age (SGA), born before 37 weeks of gestation, and have a 5-minute Apgar score of less than 7. Compared with infants born to women without hyperemesis, rates of low birth weight and preterm delivery were substantially higher among infants born to women with hyperemesis and low pregnancy weight gain (4.2% versus 12.5% and 4.9% versus 13.9%, respectively). The outcomes among infants born to women with hyperemesis with pregnancy weight gain of 7 kg (15.4 lb) or more were not different from the outcomes among women without hyperemesis. CONCLUSION: The results of this study suggest that the adverse infant outcomes associated with hyperemesis are a consequence of, and mostly limited to, women with poor maternal weight gain. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2006

Socioeconomic status and receipt of obstetric services in Canada.

OBJECTIVE: To examine differences in labor induction and cesarean delivery rates by socioeconomic status in Nova Scotia, Canada. METHODS: We studied all women in Nova Scotia who delivered between 1988 and 1995 after a singleton pregnancy. Information was obtained from the Nova Scotia Atlee Perinatal Database and the federal income tax (T1) Family Files maintained by the Small Area and Administrative Data Division of Statistics Canada (n = 76,440). Labor induction and cesarean delivery rates were contrasted by family income and other indices, with adjustment for risk factors carried out using logistic models. RESULTS: Maternal characteristics and other factors varied by socioeconomic status; in the lowest income group 4.4% of women were aged 35 years or older, and 49.4% were nonsmokers, whereas in the highest income group 17.7% were aged 35 years or older, and 88.7% were nonsmokers. Crude induction rates were similar across income groups (17.7% compared with 18.1% in the lowest compared with highest income groups), but there were significant differences in crude cesarean (17.7% compared with 21.2%) and crude primary cesarean rates (12.5% compared with 17.0%). Controlling for differences in risk factors altered these relationships. Adjusted rate ratios, 95% confidence intervals (CIs) and P values contrasting the lowest compared with highest income groups were labor induction 1.09 (95% CI 1.00-1.19), P = .05; overall cesarean delivery 1.12 (95% CI 1.03-1.23), P = .01; primary cesarean delivery 1.09 (95% CI 0.98-1.21), P = .12. CONCLUSION: Affluent women in Canada are not more likely to have labor induction or cesarean delivery compared with less affluent women. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2006

Determinants of perinatal mortality and serious neonatal morbidity in the second twin.

OBJECTIVE: To identify potential determinants of perinatal mortality and neonatal morbidity among second twins relative to first twins. METHODS: A retrospective cohort design was used to study twin deliveries in Nova Scotia from 1988 to 2002. Monoamniotic or conjoined twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal mortality and neonatal morbidity, including birth asphyxia, respiratory distress, neonatal trauma, and infection. Risk of adverse outcome of second twins relative to first-born co-twins was determined by matched-pair analysis. RESULTS: Of 1,542 twin pairs, the second twin was at greater risk of composite adverse outcome (relative risk [RR] 1.62, 95% confidence interval [CI] 1.38-1.9) than the first twin. This excess risk was evident independent of presentation, chorionicity, or infant sex but was associated with planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval. Term second twins were less likely to suffer excess morbidity with elective cesarean (RR 1.0, 95% CI 0.14-7.10) than with planned vaginal delivery (RR 3.0, 95% CI 1.47-6.11). The major contributors to neonatal morbidity in the second twin were birth asphyxia at 37 weeks or later and respiratory distress syndrome at less than 37 weeks. CONCLUSION: The second twin is at greater risk of adverse perinatal outcome than the first twin, independent of presentation, chorionicity, or infant sex. Planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval increase this infant risk. Elective cesarean delivery at term may improve perinatal outcome for the second twin. However, the number of cesarean births required to prevent one case of composite adverse outcome, assuming causality, was 33.

Adult↗
PubMed2006

Relation of pregnancy and neonatal factors to subsequent development of childhood epilepsy: a population-based cohort study.

OBJECTIVE: We examined the effect of pregnancy and neonatal factors on the subsequent development of childhood epilepsy in a population-based cohort study. PATIENTS AND METHODS: Children born between January 1986 and December 2000 in Nova Scotia, Canada were followed up to December 2001. Data on pregnancy and neonatal events and on diagnoses of childhood epilepsy were obtained through record linkage of 2 population-based databases: the Nova Scotia Atlee Perinatal Database and the Canadian Epilepsy Database and Registry. Factors analyzed included events during the prenatal, labor and delivery, and neonatal time periods. Cox proportional hazards regression models were used to estimate relative risks and 95% confidence intervals. RESULTS: There were 648 new cases of epilepsy diagnosed among 124,207 live births, for an overall rate of 63 per 100,000 person-years. Incidence rates were highest among children <1 year of age. In adjusted analyses, factors significantly associated with an increased risk of epilepsy included eclampsia, neonatal seizures, central nervous system (CNS) anomalies, placental abruption, major non-CNS anomalies, neonatal metabolic disorders, neonatal CNS diseases, previous low birth weight infant, infection in pregnancy, small for gestational age, unmarried, and not breastfeeding infant at the time of discharge from hospital. CONCLUSIONS: Our study supports the concept that prenatal factors contribute to the occurrence of subsequent childhood epilepsy.

Breast Feeding↗
PubMed2005

Severe maternal morbidity in Canada, 1991-2001.

BACKGROUND: Although death rates are often used to monitor the quality of health care, in industrialized countries maternal deaths have become rare. Severe maternal morbidity has therefore been proposed as a supplementary indicator for surveillance of the quality of maternity care. Our purpose in this study was to describe severe maternal morbidity in Canada over a 10-year period, among women with or without major pre-existing conditions. METHODS: We carried out a retrospective cohort study of severe maternal morbidity involving 2,548,824 women who gave birth in Canadian hospitals between 1991 and 2000. Thirteen conditions that may threaten the life of the mother (e.g., eclampsia) and 11 major pre-existing chronic conditions (e.g., diabetes) that could be identified from diagnostic codes were noted. RESULTS: The overall rate of severe maternal morbidity was 4.38 per 1000 deliveries. The fatality rate among these women was 158 times that of the entire sample. Rates of venous thromboembolism, uterine rupture, adult respiratory distress syndrome, pulmonary edema, myocardial infarction, severe postpartum hemorrhage requiring hysterectomy, and assisted ventilation increased substantially from 1991 to 2000. The presence of major pre-existing conditions increased the risk of severe maternal morbidity to 6-fold. INTERPRETATION: Severe maternal morbidity occurs in about 1 of 250 deliveries in Canada, with marked recent increases in certain morbid conditions such as pulmonary edema, myocardial infarction, hemorrhage requiring hysterectomy, and the use of assisted ventilation.

Adult↗
PubMed2005

Customized birth weight for gestational age standards: Perinatal mortality patterns are consistent with separate standards for males and females but not for blacks and whites.

BACKGROUND: Some currently available birth weight for gestational age standards are customized but others are not. We carried out a study to provide empirical justification for customizing such standards by sex and for whites and blacks in the United States. METHODS: We studied all male and female singleton live births and stillbirths (22 or more weeks of gestation; 500 g birth weight or over) in the United States in 1997 and 1998. White and black singleton live births and stillbirths were also examined. Qualitative congruence between gestational age-specific growth restriction and perinatal mortality rates was used as the criterion for identifying the preferred standard. RESULTS: The fetuses at risk approach showed that males had higher perinatal mortality rates at all gestational ages compared with females. Gestational age-specific growth restriction rates based on a sex-specific standard were qualitatively consistent with gestational age-specific perinatal mortality rates among males and females. However, growth restriction patterns among males and females based on a unisex standard could not be reconciled with perinatal mortality patterns. Use of a single standard for whites and blacks resulted in gestational age-specific growth restriction rates that were qualitatively congruent with patterns of perinatal mortality, while use of separate race-specific standards led to growth restriction patterns that were incompatible with patterns of perinatal mortality. CONCLUSION: Qualitative congruence between growth restriction and perinatal mortality patterns provides an outcome-based justification for sex-specific birth weight for gestational age standards but not for the available race-specific standards for blacks and whites in the United States.

Journal Article↗
PubMed2005

Fetal deaths in the United States, 1997 vs 1991.

OBJECTIVE: The purpose of this study was to examine the temporal change in fetal death risk in the US from 1991 to 1997, and to assess the extent to which changes in registration practices and labor induction have contributed to that change. STUDY DESIGN: This was a cohort study of all singleton pregnancies 20 to 43 weeks of gestation in 1991 and 1997 in the US. RESULTS: From 1991 to 1997, the overall fetal death rate fell from 77.6 to 67.8 per 10,000 total births. However, fetal deaths at 20 to 22 weeks as a proportion of total births increased from 14.5 to 16.9 per 10,000. In a Cox regression analysis, the crude period effect (1997 vs 1991) at 40 to 43 weeks was 0.87 (95% CI 0.80-0.94), and remained virtually unchanged (HR 0.88, 95% CI 0.81-0.96) after adjustment for maternal sociodemographic, medical, and lifestyle risk factors. In ecologic (Poisson regression) analysis based on states as the unit of analysis, the crude period effect in non-Hispanic whites (RR 0.79, 95% CI 0.74-0.84) disappeared (RR 0.98, 95% CI 0.82-1.16) after adjusting for induction of labor. The effect of induction in blacks was limited to 42 to 43 weeks in those at high risk. CONCLUSION: Increased registration is probably responsible for an increase in fetal death risk at 20 to 22 weeks of gestation, whereas the increasing trend toward routine labor induction at and after term appears to have reduced the risk of fetal death, especially among whites.

Adult↗
PubMed2005

Trends in twin preterm birth subtypes in the United States, 1989 through 2000: impact on perinatal mortality.

OBJECTIVE: We examined trends in twin preterm birth <37 weeks following ruptured membranes (ROM), medically indicated preterm birth, and preterm birth following spontaneous onset of labor (PTL). We further examined whether the changes in preterm birth subtypes were associated with trends in twin perinatal mortality. STUDY DESIGN: We carried out a retrospective cohort study of 1,172,405 twin live births and stillbirths delivered in the US between 1989 and 2000. Trends in preterm birth subtypes and perinatal mortality (stillbirths at > or = 22 weeks plus neonatal deaths within 28 days) were examined through ecological logistic regression models after adjusting for confounders. RESULTS: Twin preterm birth among whites increased from 46.6% in 1989 to 1990 to 56.7% in 1999 to 2000, and from 56.1% to 61.0% among blacks over the same period. Medically indicated preterm birth increased by 50% (95% CI 49-52) among whites, and by 33% (95% CI 29-36) among blacks. PTL increased by 24% among whites, but remained fairly unchanged among blacks between the two periods. Preterm birth following ROM also did not change between the 2 periods among whites, but declined by 7% among blacks. Perinatal mortality among twin births declined by 41% (95% CI 38-44) among whites, and by 37% (95% CI 32-42) among blacks between 1989 and 1990 and 1999 and 2000. This mortality decline was most closely associated with the increase in medically indicated preterm birth among whites, and with the decrease in preterm birth following ROM among blacks. CONCLUSION: Temporal trends in twin preterm birth varied substantially based on underlying subtypes and race. The increase in medically indicated preterm birth is associated with a large reduction in perinatal mortality.

Adult↗
PubMed2005

Fetal and neonatal mortality among twin gestations in a Canadian population: the effect of intrapair birthweight discordance.

The purpose of this study was to examine the association between intrapair birthweight discordance and fetal and neonatal mortality. This was a historical cohort study, using the Statistics Canada linked birth-infant death file. Twin births in Canada (excluding Ontario) for the period 1986-1997 were studied. Outcome measures were fetal and neonatal mortality. Among 59,034 twin births, 53% had 0 to 9% birthweight difference; 30% had 10 to 19% discordance; 11% had 20 to 29% discordance; and 6% had > or = 30% discordance. Maternal age, parity, sex discordance, and gestational age were important factors affecting birth weight discordance. Fetal death rates were 0.95, 1.26, 3.14, and 11.10%, respectively, in infants with a birthweight discordance of 0 to 9, 10 to 19, 20 to 29, and > or = 30%. Corresponding figures for neonatal death rates were 1.90, 2.32, 3.05, and 8.86%, respectively. Adjustment for important confounding variables including the actual birthweight and gestational age substantially reduced the birthweight discordance-related risk of fetal and neonatal mortality, but the results remained statistically significant and clinically important. The birthweight discordance-related risk of fetal and neonatal mortality was higher in smaller twins than in larger twins and higher in infants with gestational age > or = 37 weeks than those < 37 weeks. Birthweight discordance is an important risk factor for fetal and neonatal mortality, and the birthweight discordance-related risk of fetal and neonatal mortality is higher in smaller twins than in larger twins and higher in term twins than in preterm twins.

Adult↗
PubMed2005

Risk of maternal postpartum readmission associated with mode of delivery.

OBJECTIVE: To determine whether cesarean and operative vaginal deliveries are associated with an increased risk of maternal rehospitalization compared with spontaneous vaginal delivery. METHODS: A population-based cohort study was conducted by using the Canadian Institute for Health Information's Discharge Abstract Database between 1997/1998 and 2000/2001, which included 900,108 women aged 15-44 years with singleton live births (after excluding several selected obstetric conditions). RESULTS: A total of 16,404 women (1.8%) were rehospitalized within 60 days after initial discharge. Compared with spontaneous vaginal delivery (rate 1.5%), cesarean delivery was associated with a significantly increased risk of postpartum readmission (rate 2.7%, odds ratio [OR] 1.9, 95% confidence interval [CI] 1.8-1.9); ie, there was 1 excess postpartum readmission per 75 cesarean deliveries. Diagnoses associated with significantly increased risks of readmission after cesarean delivery (compared with spontaneous vaginal delivery) included pelvic injury/wounds (rate 0.86% versus 0.06%, OR 13.4, 95% CI 12.0-15.0), obstetric complications (rate 0.23% versus 0.08%, OR 3.0, 95% CI 2.6-3.5), venous disorders and thromboembolism (rate 0.07% versus 0.03%, OR 2.7, 95% CI 2.1-3.4), and major puerperal infection (rate 0.45% versus 0.27%, OR 1.8, 95% CI 1.6-1.9). Women delivered by forceps or vacuum were also at an increased risk of readmission (rates 2.2% and 1.8% versus 1.5%; OR forceps: 1.4, 95% CI 1.3-1.5; OR vacuum: 1.2, 95% CI 1.2-1.3, respectively). Higher readmission rates after operative vaginal delivery were due to pelvic injury/wounds, genitourinary conditions, obstetric complications, postpartum hemorrhage, and major puerperal infection. CONCLUSION: Compared with spontaneous vaginal delivery, cesarean delivery, and operative vaginal delivery increase the risk of maternal postpartum readmission. LEVEL OF EVIDENCE: II-2.

Adolescent↗
PubMed2005

Trends in preterm birth and perinatal mortality among singletons: United States, 1989 through 2000.

OBJECTIVE: Despite the recent increase in preterm birth in the United States, trends in preterm birth subtypes have not been adequately examined. We examined trends in preterm birth among singletons following ruptured membranes, medical indications, and spontaneous preterm birth and evaluated the impact of these trends on perinatal mortality. METHODS: A population-based, retrospective cohort study comprising 46,375,578 women (16% blacks) who delivered singleton births in the United States, 1989 through 2000, was performed. Rates of preterm birth (< 37 weeks), their subtypes, and associated perinatal mortality (stillbirths at >/= 22 weeks plus neonatal deaths within 28 days), before and after adjustment for potential confounders, were derived from ecological logistic regression models. RESULTS: Preterm birth rates increased by 14% (95% confidence interval 13-15%) among whites from 8.3% to 9.4% and decreased by 15% (95% confidence interval 14-16%) among blacks from 18.5% to 16.2% between 1989 and 2000. Among whites, preterm birth following ruptured membranes declined by 23%, medically indicated preterm birth increased by 55%, and spontaneous preterm birth increased by 3%. Among blacks, preterm birth following ruptured membranes declined by 37%, medically indicated preterm birth increased by 32%, and spontaneous preterm birth decreased by 27%. The largest decline in perinatal mortality among whites was associated with increases in medically indicated preterm birth, whereas the largest decline in perinatal mortality among blacks was associated with declines in preterm birth following ruptured membranes and spontaneous preterm birth. CONCLUSION: Temporal trends in preterm birth varied substantially based on underlying subtype and maternal race. The recent increase in medically indicated preterm birth was associated with a favorable reduction in perinatal mortality.

Adolescent↗