The Association Between Socio-demographic Factors, Dental Problems, and Preterm Labor for Pregnant Women Residing in Hawai'i

Periodontal disease during pregnancy has the potential to increase the risk of adverse perinatal outcomes including preterm labor (PTL), prematurity, and low birth weight (LBW). Despite professional recommendations on the importance and safety of dental assessments and treatments, the rate of dental care utilization during pregnancy remains low. The purpose of this study was to document the utilization of dental services and explore the relationships among socio-demographic factors, dental problems, and PTL in pregnant women residing in Hawai'i. Hawai'i Pregnancy Risk Assessment Monitoring System (PRAMS) survey results were analyzed from 4,309 women who experienced live births between the years 2009-2011. Results revealed that 2 in 5 women in Hawai'i had their teeth cleaned during pregnancy, while 1 in 5 reported seeing a dentist for a dental problem. Women who reported having a dental problem during pregnancy were more likely to experience PTL (OR=1.46, 95% CI=1.10-1.94, P=.008) compared to women without a dental problem. In addition, Native Hawaiian and Part-Hawaiian women were more likely to experience PTL (OR=1.73, 95% CI=1.22-2.46, P=.002) compared to Caucasian women. These findings document the underutilization of dental services in pregnant women in Hawai'i and reveal an association between poor dental care and PTL. Identification of groups at risk for maternal complications may assist in the development of programs that are sensitive to the diverse cultures and variability of community resources that exist throughout Hawai'i.

Post-hoc analysis of vitamin D status and reduced risk of preterm birth in two vitamin D pregnancy cohorts compared with South Carolina March of Dimes 2009-2011 rates

BACKGROUND

Two vitamin D pregnancy supplementation trials were recently undertaken in South Carolina: The NICHD (n=346) and Thrasher Research Fund (TRF, n=163) studies. The findings suggest increased dosages of supplemental vitamin D were associated with improved health outcomes of both mother and newborn, including risk of preterm birth (<37 weeks gestation). How that risk was associated with 25(OH)D serum concentration, a better indicator of vitamin D status than dosage, by race/ethnic group and the potential impact in the community was not previously explored. While a recent IOM report suggested a concentration of 20 ng/mL should be targeted, more recent work suggests optimal conversion of 25(OH)D-1,25(OH)2D takes place at 40 ng/mL in pregnant women.

OBJECTIVE

Post-hoc analysis of the relationship between 25(OH)D concentration and preterm birth rates in the NICHD and TRF studies with comparison to Charleston County, South Carolina March of Dimes (CC-MOD) published rates of preterm birth to assess potential risk reduction in the community.

METHODS

Using the combined cohort datasets (n=509), preterm birth rates both for the overall population and for the subpopulations achieving 25(OH)D concentrations of ≤20 ng/mL, >20 to <40 ng/mL, and ≥40 ng/mL were calculated; subpopulations broken down by race/ethnicity were also examined. Log-binomial regression was used to test if an association between 25(OH)D serum concentration and preterm birth was present when adjusted for covariates; locally weighted regression (LOESS) was used to explore the relationship between 25(OH)D concentration and gestational age (weeks) at delivery in more detail. These rates were compared with 2009-2011 CC-MOD data to assess potential risk reductions in preterm birth.

RESULTS

Women with serum 25(OH)D concentrations ≥40 ng/mL (n=233) had a 57% lower risk of preterm birth compared to those with concentrations ≤20 ng/mL [n=82; RR=0.43, 95% confidence interval (CI)=0.22,0.83]; this lower risk was essentially unchanged after adjusting for covariates (RR=0.41, 95% CI=0.20,0.86). The fitted LOESS curve shows gestation week at birth initially rising steadily with increasing 25(OH)D and then plateauing at ∼40 ng/mL. Broken down by race/ethnicity, there was a 79% lower risk of preterm birth among Hispanic women with 25(OH)D concentrations ≥40 ng/mL (n=92) compared to those with 25(OH)D concentrations ≤20 ng/mL (n=29; RR=0.21, 95% CI=0.06,0.69) and a 45% lower risk among Black women (n=52 and n=50; RR=0.55, 95% CI=0.17,1.76). There were too few white women with low 25(OH)D concentrations for assessment (n=3). Differences by race/ethnicity were not statistically significant with 25(OH)D included as a covariate. Compared to the CC-MOD reference group, women with serum concentrations ≥40 ng/mL in the combined cohort had a 46% lower rate of preterm birth overall (n=233, p=0.004) with a 66% lower rate among Hispanic women (n=92, p=0.01) and a 58% lower rate among black women (n=52, p=0.04).

CONCLUSIONS

In this post-hoc analysis, achieving a 25(OH)D serum concentration ≥40 ng/mL significantly decreased the risk of preterm birth compared to ≤20 ng/mL. These findings suggest the importance of raising 25(OH)D levels substantially above 20 ng/mL; reaching 40 ng/mL during pregnancy would reduce the risk of preterm birth and achieve the maximal production of the active hormone.

Early gestational weight gains within current recommendations result in increased risk of gestational diabetes mellitus among Korean women

BACKGROUND

We prospectively assessed whether maternal weight gain at 24-28 weeks of gestation (MWG24) influences the risk of developing gestational complications, such as gestational diabetes mellitus (GDM) and other adverse pregnancy outcomes, in pregnant Korean women.

METHODS

Maternal weight gain from self-reported pre-pregnancy weight until 24-28 weeks of gestation was measured in 731 pregnant women, and an expected MWG24 was determined using the Institute of Medicine 2009 guidelines. Glucose tolerance, insulin resistance, insulin secretory capacity, anthropometric measurements, lipid profiles, nutrient intakes and pregnancy outcomes were evaluated at 24-28 weeks of gestation. The adjusted odds ratios (ORs) for GDM, large-for-gestational-age infants, small-for-gestational-age infants and preterm delivery were determined according to maternal weight gain by logistic regression analysis after adjusting for covariates.

RESULTS

Compared with a normal MWG24, an inadequate MWG24 reduced the OR (0.565) for GDM, but an excessive MWG24 did not affect the OR (0.854). However, ORs for preterm delivery were significantly higher in both inadequate and excessive MWG24 groups in comparison with the normal MWG24. There were no other adverse pregnancy outcomes due to the inadequate MWG24. MWG24 was not associated with a significant increase in ORs for delivering large-for-gestational-age or small-for-gestational-age infants or delivery by caesarean section. Although energy intake was less than the estimated energy requirement in all groups, MWG24 was linearly associated with energy intake such that energy balance was positive in the excessive MWG24 group.

CONCLUSIONS

This study suggests that both target weight gain and energy intake recommendations for early pregnancy may not be optimal for Korean women and that race-specific recommendations are needed to decrease the risk of GDM without increasing adverse pregnancy outcomes.

Population-level correlates of preterm delivery among black and white women in the U.S

OBJECTIVE

This study examined the ability of social, demographic, environmental and health-related factors to explain geographic variability in preterm delivery among black and white women in the US and whether these factors explain black-white disparities in preterm delivery.

METHODS

We examined county-level prevalence of preterm delivery (20-31 or 32-36 weeks gestation) among singletons born 1998-2002. We conducted multivariable linear regression analysis to estimate the association of selected variables with preterm delivery separately for each preterm/race-ethnicity group.

RESULTS

The prevalence of preterm delivery varied two- to three-fold across U.S. counties, and the distributions were strikingly distinct for blacks and whites. Among births to blacks, regression models explained 46% of the variability in county-level risk of delivery at 20-31 weeks and 55% for delivery at 32-36 weeks (based on R-squared values). Respective percentages for whites were 67% and 71%. Models included socio-environmental/demographic and health-related variables and explained similar amounts of variability overall.

CONCLUSIONS

Much of the geographic variability in preterm delivery in the US can be explained by socioeconomic, demographic and health-related characteristics of the population, but less so for blacks than whites.

Attitudes of healthcare providers towards non-initiation and withdrawal of neonatal resuscitation for preterm infants in Mongolia

Antenatal parental counselling by healthcare providers is recommended to inform parents and assist with decision-making before the birth of a child with anticipated poor prognosis. In the setting of a low-income country, like Mongolia, attitudes of healthcare providers towards resuscitation of high-risk newborns are unknown. The purpose of this study was to examine the attitudes of healthcare providers regarding ethical decisions pertaining to non-initiation and withdrawal of neonatal resuscitation in Mongolia. A questionnaire on attitudes towards decision-making for non-initiation and withdrawal of neonatal resuscitation was administered to 113 healthcare providers attending neonatal resuscitation training courses in 2009 in Ulaanbaatar, the capital and the largest city of Mongolia where -40% of deliveries in the country occur. The questionnaire was developed in English and translated into Mongolian and included multiple choices and free-text responses. Participation was voluntary, and anonymity of the participants was strictly maintained. In total, 113 sets of questionnaire were completed by Mongolian healthcare providers, including neonatologists, paediatricians, neonatal and obstetrical nurses, and midwives, with 100% response rate. Ninety-six percent of respondents were women, with 73% of participants from Ulaanbaatar and 27% (all midwives) from the countryside. The majority (96%) of healthcare providers stated they attempt pre-delivery counselling to discuss potential poor outcomes when mothers present with preterm labour. However, most (90%) healthcare providers stated they feel uncomfortable discussing not initiating or withdrawing neonatal resuscitation for a baby born alive with little chance of survival. Religious beliefs and concerns about long-term pain for the baby were the most common reasons for not initiating neonatal resuscitation or withdrawing care for a baby born too premature or with congenital birth-defects. Most Mongolian healthcare providers provide antenatal counselling to parents regarding neonatal resuscitation. Additional research is needed to determine if the above-said difficulty with counselling stems from deficiencies in communication training and whether these same counselling-related issues exist in other countries. Future educational efforts in teaching neonatal resuscitation in Mongolia should incorporate culturally-sensitive training on antenatal counselling.

Innate immune system gene polymorphisms in maternal and child genotype and risk of preterm delivery

OBJECTIVE

There is little information about the combination of genetic variability in pregnant women and their children in relation to the risk of preterm delivery (PTD). In a sub-cohort of 487 non-Hispanic white and 288 African-American mother/child pairs, the Pregnancy Outcomes and Community Health Study assessed 10 functional polymorphisms in 9 genes involved in innate immune function.

METHODS

Race-stratified weighted logistic regression models were used to calculate odds ratios for genotype and PTD/PTD subtypes. Polymorphisms significantly associated with PTD/PTD subtypes were tested for mother/child genotype interactions.

RESULTS

Three maternal polymorphisms (IL-1 receptor antagonist intron two repeat (IL-1RN), matrix metalloproteinase- -C1562T, and TNF receptor two M196R (TNFR2)) and three child polymorphisms (IL1-RN, tumor necrosis factor-alpha -G308A, and TNFR2) were associated with PTD, but associations varied by PTD subtype and race. Two interactions were detected for maternal and child genotype. Among non-Hispanic white women, the odds of PTD was higher when both mother and child carried the IL-1RN allele two (additive interaction p < 0.05). Among African-American women, the odds of PTD were higher when both mother and child carried the TNFR2 R allele (multiplicative interaction p < 0.05).

CONCLUSION

These results highlight the importance of assessing both maternal and child genotype in relation to PTD risk.

National trends and racial differences in late preterm induction

OBJECTIVE

The objective of the study was to determine the trends and racial differences in late preterm induction (LPI) of labor in the United States.

STUDY DESIGN

Data from the National Vital Statistics System were used to identify women eligible for induction between 34 and 42 weeks' gestation from 1991 to 2006. Annual LPI rates were calculated, and maternal race/ethnicity was classified into 4 groups. Changes in the frequency and odds of LPI, stratified by race/ethnicity, were assessed using logistic regression.

RESULTS

Among the 42.0 million eligible women, LPI rates increased from 0.46% to 1.37% (P < .01) over 16 years. LPI rates were highest for black women (P < .01) each year, and after adjusting for confounding factors, the odds of LPI were highest (P < .01) and rose most rapidly (P < .01) for black women (non-Hispanic white: odds ratio [OR], 1 [referent]; Hispanic white: OR, 0.76; black: OR, 1.31; other: OR, 0.81; P < .01).

CONCLUSION

LPI rates were persistently highest and rose most rapidly for black women.

Disparate rates of persistent smoking and drug use during pregnancy of women of Hawaiian ancestry

BACKGROUND

Significant disparity in smoking rates has been previously reported in pregnant and non-pregnant women of Native Hawaiian ancestry. Disparities in drug use rates have also been reported in non-pregnant women of Native Hawaiian ancestry.

OBJECTIVE

We undertook this study to compare rates of smoking and drug use during pregnancy among women in Hawaii to see if these differences are associated with disparities in pregnancy complications among Native Hawaiian women.

METHODS

Women were enrolled in the Pacific Research Center on Early Human Development study from July 2007 to January 2008, according to approved protocols. Persistent smoking was defined as self-reported smoking within 1 week of admission for labor. Drug use data was assessed by self-report, or if available, toxicology tests at the time of labor.

RESULTS

There were 868 women enrolled in the study during this period. Women of Hawaiian/part-Hawaiian ancestry comprised 22% of the study population. Rates of persistent smoking and drug use among Hawaiian women were significantly higher than the remainder of the study population (21% and 8.3% vs. 7.8% and 2.1%, respectively, P < .001 for both). Methamphetamine use was associated with an almost 5-fold increase in preterm birth and smoking a 3.4% decrease in birth weights.

DISCUSSION AND CONCLUSION

Women of Hawaiian ancestry continue to smoke and use illicit drugs during pregnancy at significantly higher rates than women of other ethnic groups in Hawaii. In addition to the immediate effects on pregnancy, long-term adverse outcomes of in utero exposures of the offspring remain an important health disparity.

Prepregnancy depressive mood and preterm birth in black and white women: findings from the CARDIA Study

OBJECTIVES

We examine associations among race, prepregnancy depressive mood, and preterm birth (<37 weeks gestation) in a cohort study of black and white women.

METHODS

We tested for mediation of the association between race and preterm birth by prepregnancy depressive mood among 555 women enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.

RESULTS

Black women had significantly higher levels of prepregnancy depressive mood (modified CES-D score 13.0 vs. 9.5, t = -4.64, p < 0.001). After adjustment for covariates, black women had 2.70 times the odds of preterm birth as white women (95% confidence interval [CI] 1.41, 5.17). When adding prepregnancy depressive mood to this model, higher depressive mood was associated with greater odds of preterm birth (odds ratio [OR] 1.04; 95% CI 1.01, 1.07), and the effect of black race was attenuated (OR 2.47, 95% CI 1.28, 4.77).

CONCLUSIONS

Our data suggest that prepregnancy depressive mood may be a risk factor for preterm birth among black and white women.

Racial differences in birth outcomes: the role of general, pregnancy, and racism stress

OBJECTIVE

This study examined the role of psychosocial stress in racial differences in birth outcomes.

DESIGN

Maternal health, sociodemographic factors, and 3 forms of stress (general stress, pregnancy stress, and perceived racism) were assessed prospectively in a sample of 51 African American and 73 non-Hispanic White pregnant women.

MAIN OUTCOME MEASURES

The outcomes of interest were birth weight and gestational age at delivery. Only predictive models of birth weight were tested as the groups did not differ significantly in gestational age.

RESULTS

Perceived racism and indicators of general stress were correlated with birth weight and tested in regression analyses. In the sample as a whole, lifetime and childhood indicators of perceived racism predicted birth weight and attenuated racial differences, independent of medical and sociodemographic control variables. Models within each race group showed that perceived racism was a significant predictor of birth weight in African Americans, but not in non-Hispanic Whites.

CONCLUSIONS

These findings provide further evidence that racism may play an important role in birth outcome disparities, and they are among the first to indicate the significance of psychosocial factors that occur early in the life course for these specific health outcomes.

Amniotic fluid interleukin-1beta and interleukin-8 concentrations: racial disparity in preterm birth

The purpose of this study is to examine the racial differences between interleukin (IL)-1beta and IL-8 concentrations in the amniotic fluid of black and white women with spontaneous preterm birth (PTB). In this study, 350 amniotic fluid samples were collected: 165 PTB cases (<36 weeks' gestation; 52 blacks and 113 whites) and 185 controls (normal term delivery >37 weeks' gestation; 87 blacks and 98 whites). Amniotic fluid IL-1beta and IL-8 concentrations were measured by immunoassay. Wilcoxon nonparametric test was performed for statistical analysis. In data stratified by race, the median IL-1beta concentration was significantly higher in black cases (80 pg/mL) compared to black controls (23.7 pg/mL; P < .0001), and the difference was nonsignificant in white cases (25.5 pg/mL) compared to white controls (21.3 pg/mL; P = .1). IL-8 concentration was not higher in black cases (742.2 pg/mL) compared to black controls (731.4 pg/mL; P = .9), whereas it was higher in white cases (1362.3 pg/mL) compared to white controls (533.5 pg/mL; P = .0005). Between races, IL-1beta was significantly higher in blacks (P < .0001) than in whites in PTB, whereas no significant difference was noticed in IL-8 concentration between races (P = .1). In PTB, the cytokine footprint differs in the amniotic fluid between racial groups. IL-1beta is higher in black and IL-8 in white PTB. These differences in the amniotic fluid cytokine concentration might not explain the racial disparity in the PTB rate, but they are suggestive of different processes of PTB in whites and blacks.

Paternal race is a risk factor for preterm birth

OBJECTIVE

The purpose of this study was to test the hypothesis that paternal race influences the risk for preterm birth.

STUDY DESIGN

We conducted a population-based cohort study to examine the association of paternal race with preterm birth using the Missouri Department of Health's birth registry from 1989-1997. Birth outcomes were analyzed in 4 categories: white mother/white father, white mother/black father, black mother/white father, and black mother/ black father.

RESULTS

We evaluated 527,845 birth records. The risk of preterm birth at <35 weeks of gestation increased when either parent was black (white mother/black father: adjusted odds ratio, 1.28 [95% CI, 1.13, 1.46], black mother/white father: adjusted odds ratio, 2.10 [95% CI, 1.68, 2.62], and black mother/black father: adjusted odds ratio, 2.28 [95% CI, 2.18, 2.39]) and was even higher for extreme preterm birth (<28 weeks of gestation) in pregnancies with a nonwhite parent.

CONCLUSION

Paternal black race is associated with an increased risk of preterm birth in white mothers, which suggests a paternal contribution to fetal genotype that ultimately influences the risk for preterm delivery.

Preterm delivery and cytokine gene polymorphisms

OBJECTIVE

To investigate the association of preterm delivery with polymorphisms of IL-6, IL-10, IFN-gamma, TGFbeta1 and TNF-alpha genes.

STUDY DESIGN

The study group consisted of 45 Caucasian, 81 mixed race and 13 black women with a history of preterm labor, consecutively referred. All of them had delivered before 37 weeks' gestation. The control group was composed of 56 Caucasian, 48 mixed race and 15 black women with successful pregnancy. DNA was extracted from whole blood, and cytokine genotyping was performed using the Cytokine Genotyping Tray (One-Lambda, Canoba Park, California). The polymorphisms analyzed were: TNF-alpha (-08 G --> A), IL-10 (-1082 G --> A), IL-6 (-174 G --> C), TGFbeta1 (+10 T --> C e 25 C --> G) and IFN-gamma (+874 A --> T).

RESULTS

There were no differences in genotype frequencies of IL-10, TGF-beta, TNF-alpha or IL-6 polymorphisms between the groups. In the Caucasian group there was a trend toward increased frequencies of the TT genotype of IFN-gamma in controls.

CONCLUSION

Preterm delivery is not associated with TNF-alpha (-308), IL-10 (-1082), IL-6 (-174), TGFbeta1 (+10 e 25) or IFN-gamma (+874) polymorphisms.

Cervical length at 18-22 weeks of gestation for prediction of spontaneous preterm delivery in Hong Kong Chinese women

OBJECTIVE

To assess the value of a single cervical length measurement by transvaginal sonography (TVS) at the time of mid-trimester anomaly scan for predicting spontaneous preterm delivery (SPD) among Chinese women.

METHODS

A prospective observational study was carried out involving 2880 subjects with singleton pregnancies and confirmed gestational age. Cervical length was measured at 18-22 weeks of gestation.

RESULTS

The incidence of SPD < 34 weeks and < 37 weeks were 0.7% and 3.7%, respectively. Women with SPD < 34 weeks and SPD < 37 weeks had shorter median cervical lengths (32.6 mm and 36.2 mm, respectively) than those with term deliveries (37.6 mm) (P = 0.006 and 0.025, respectively). The predictive performance of cervical length was better for SPD < 34 weeks compared with < 37 weeks. A cervical length < or = 27 mm, which corresponded to the 4th centile, occurred in 36.8%, 62.5% and 100% of those with SPD < 34, < 30 and < 26 weeks, respectively. The positive likelihood ratio (LR) of a cervical length < or = 27 mm in predicting SPD < 34 weeks was 9.8. Using logistic regression, both short cervix and funneling were independent predictors for SPD < 34 weeks of gestation. The coexistence of funneling and a cervical length < or = 27 mm gave a positive predictive value (PPV) and LR of SPD < 34 weeks of 14.7% and 26.0, respectively.

CONCLUSIONS

Mid-trimester cervical length is predictive of SPD in Chinese women. However, given the low PPV of a short cervical length, its clinical utility is still limited in low-risk populations.

Birth outcomes in teenage pregnancies

OBJECTIVE

To evaluate and characterize the racial/ethnic differences in obstetric outcomes of early and late teenagers in California.

METHODS

A data-set linking birth and death certificates with maternal and neonatal hospital discharge records in California was utilized to identify nulliparous women (11 to 29 years of age) who delivered between January 1,1992 and December 31,1997. Pregnancy outcomes of early (11-15 year) and late (16-19 year) teenagers were compared to those of a control group of women aged 20-29.

RESULTS

Early (n = 31 232) and late teens (n = 271 470) demonstrated greater neonatal and infant mortality and major neonatal morbidities (delivery < 37 weeks of gestation and birthweight < 2500 g) when compared to pregnancies in the older control women (n = 662 752). Ethnicity adversely affected outcome with African-Americans of all ages having worse outcomes than whites. The higher rate of adverse obstetric outcomes among the teenage pregnancies occurred despite a lower cesarean section rate and was consistent across all ethnic groups.

CONCLUSIONS

When compared to women aged 20-29, all teen pregnancies were associated with higher rates of poor obstetric outcomes. Other factors besides teen pregnancy appear to be responsible for poor outcomes in certain ethnic groups.

Precursors of Preterm Birth: Comparison of Three Ethnic Groups in the Middle East and the United States

OBJECTIVE

To examine factors related to preterm birth in three ethnic groups and in three different countries.

DESIGN

Data were obtained on a convenience sample of 118 Lebanese mothers, 104 Egyptian mothers, 40 Mexican American mothers, and 32 White American mothers from Southern California. About half of each cohort had delivered a preterm newborn and half a full-term newborn. Mothers with premature or full-term newborns completed a questionnaire by interview. Analysis compared ethnic groups and preterm- versus full-term birth groups. Multiple logistic regression determined relatedness to outcome.

RESULTS

Descriptive factors differed among groups, but not for preterm versus full-term newborn groups. Significant factors for premature birth were vaginal infections, stress, smoking, drug use, and protein intake. Factors significantly related to preterm birth in the Middle-Eastern and American groups were almost identical: social support, stress, and exercise. Smoking was related only in the American group.

CONCLUSIONS

These data suggest risk factors are similar across nations and ethnic groups. Prenatal counseling and programs should address these four issues.

The epidemiology of preterm labour

Although the definition of preterm birth is birth before 37 completed weeks, the major transition in terms of needing special care occurs between 34 and 37 weeks. The Homo sapiens neonate is born much more immature than other anthropoid species, perhaps because earlier birth has evolved to avoid the large head of the human fetus becoming impacted in the small pelvis of the mother, who has become adapted to a bipedal gait. The main burden of preterm birth exists in developing countries. There are no accurate recent worldwide data, but estimates of preterm birth rates range from 5% in developed countries to 25% in developing countries. The preterm delivery rate has been relatively stable at 5-10% in developed countries for many years. The North Thames database of 517,381 pregnancies demonstrates significant ethnic variation in preterm birth rates, with higher rates in black women. This is associated with an accelerated rate of maturity in the black fetus and neonate, with correspondingly lower gestation-specific neonatal mortality rates below 38 weeks, and higher at 38 weeks of gestation and beyond. Ethnic differences can explain only a very small proportion of global preterm births. The greatest aetiological factor worldwide is infection, mainly due to malaria and HIV. In developed countries, iatrogenic delivery is responsible for almost half of the births between 28 and 35 weeks; hypertension and pre-eclampsia are the major pathologies. Other factors include multiple pregnancy, intrauterine growth restriction, maternal stress and heavy physical work.

Self-reported experiences of racial discrimination and Black-White differences in preterm and low-birthweight deliveries: the CARDIA Study

OBJECTIVES

We examined the effects of self-reported experiences of racial discrimination on Black-White differences in preterm (less than 37 weeks gestation) and low-birthweight (less than 2500 g) deliveries.

METHODS

Using logistic regression models, we analyzed data on 352 births among women enrolled in the Coronary Artery Risk Development in Young Adults Study.

RESULTS

Among Black women, 50% of those with preterm deliveries and 61% of those with low-birthweight infants reported having experienced racial discrimination in at least 3 situations; among White women, the corresponding percentages were 5% and 0%. The unadjusted odds ratio for preterm delivery among Black versus White women was 2.54 (95% confidence interval [CI]=1.33, 4.85), but this value decreased to 1.88 (95% CI=0.85, 4.12) after adjustment for experiences of racial discrimination and to 1.11 (95% CI=0.51, 2.41) after additional adjustment for alcohol and tobacco use, depression, education, and income. The corresponding odds ratios for low birthweight were 4.24 (95% CI=1.31, 13.67), 2.11 (95% CI=0.75, 5.93), and 2.43 (95% CI=0.79, 7.42).

CONCLUSIONS

Self-reported experiences of racial discrimination were associated with preterm and low-birthweight deliveries, and such experiences may contribute to Black-White disparities in perinatal outcomes.

Ethnicity and birth outcome: New Zealand trends 1980-2001. Part 1. Introduction, Methods, Results and Overview

BACKGROUND

New Zealand Government policy during the past decade has placed a high priority on closing socioeconomic and ethnic gaps in health outcome.

AIM

To analyse New Zealand's trends in preterm and small for gestational age (SGA) births and late fetal deaths during 1980-2001 and to undertake ethnic specific analyses, resulting in risk factor profiles, for each ethnic group.

METHODS

De-identified birth registration data from 1 189 120 singleton live births and 5775 stillbirths were analysed for the period 1980-2001. Outcomes of interest included preterm birth, SGA and late fetal death while explanatory variables included maternal ethnicity, age and New Zealand Deprivation Index decile. Trend analysis was undertaken for 1980-1994 while multivariate logistic regression was used to explore risk factors for 1996-2001.

RESULTS

During 1980-1994, preterm birth rates were highest amongst Maori women. Preterm rates increased by 30% for European/other women, in contrast to non-significant declines of 7% for Maori women and 4% for Pacific women during this period. During the same period, rates of SGA were highest amongst Maori women. Rates of SGA declined by 30% for Pacific women, 25% for Maori women and 19% for European/other women during this period. Rates of late fetal death were highest amongst Pacific women during 1980-1994, but declined by 49% during this period, the rate of decline being similar for all ethnic groups.

CONCLUSIONS

The marked differences in both trend data and risk factor profiles for women in New Zealand's largest ethnic groups would suggest that unless ethnicity is specifically taken into account in future policy and planning initiatives, the disparities seen in this analysis might well persist into future generations.

Psychosocial factors and preterm birth among African American and White women in central North Carolina

OBJECTIVES

We assessed associations between psychosocial factors and preterm birth, stratified by race in a prospective cohort study.

METHODS

We surveyed 1898 women who used university and public health prenatal clinics regarding various psychosocial factors.

RESULTS

African Americans were at higher risk of preterm birth if they used distancing from problems as a coping mechanism or reported racial discrimination. Whites were at higher risk if they had high counts of negative life events or were not living with a partner. The association of pregnancy-related anxiety with preterm birth weakened when medical comorbidities were taken into account. No association with preterm birth was found for depression, general social support, or church attendance.

CONCLUSIONS

Some associations between psychosocial variables and preterm birth differed by race.

Preterm birth and maternal country of birth in a French district with a multiethnic population

OBJECTIVES

This analysis explores the association between preterm birth and maternal country of birth in a French district with a multiethnic population.

DESIGN

Prospective observational study.

SETTING

District of Seine-Saint-Denis in France

POPULATION

48,746 singleton live births from a population-based birth register between October 1998 and December 2000.

METHODS

We compare preterm birth rates by mother's country of birth controlling for demographic and obstetric factors as well as insurance coverage and timing of initiation of antenatal care.

MAIN OUTCOME MEASURES

Overall preterm birth rates and preterm birth rates by timing of delivery (<33 weeks versus 33-36 weeks of gestation), mode of onset (spontaneous or indicated preterm birth) and the presence of hypertension in pregnancy.

RESULTS

Women born in Northern Africa, Southern Europe and South/East Asia did not have higher preterm birth rates than women born in continental France. Rates were significantly higher for women born in the overseas French districts in the Caribbean and Indian Ocean and Sub-Saharan Africa. Excess risk was greatest for early preterm births, medically indicated births and preterm births associated with hypertension.

CONCLUSIONS

Patterns of preterm birth with relation to timing, mode of onset and medical complications among of Afro-Caribbean origin should be confirmed in future research.

The Utility of fFN for the Prediction of Preterm Birth in Twin Gestations

OBJECTIVE

To determine the sensitivity, specificity, and positive predictive value (PPV) of fetal fibronectin (fFN) and to determine its usefulness, in conjunction with selected other clinical assessment measures, in the prediction of preterm birth for women with twin gestations.

DESIGN

A prospective, descriptive, longitudinal design.

SETTING

An obstetrical high-risk clinic that received patient referrals from several surrounding communities in central Texas.

PATIENTS/PARTICIPANTS

Forty-eight women identified with twin gestations prior to the 22nd week of pregnancy; primarily of Hispanic ethnicity.

MAIN OUTCOME MEASURES

A substantial number of outcome variables were assessed in this study. In the present report, data derived from weekly assessments for the identification of the presence of fFN, the diagnosis of bacterial vaginosis, and the measurement of cervical length were reviewed for their relationship to prematurity, birth weight, birth weight discordancy and placental chorionicity.

RESULTS

The relative risk of birth prior to 35 weeks gestation, fetal death, or discordance of twin birth weights of greater than 20% was 2.22 (CI: 1.09, 4.55, P < 0.015) when fFN was found to be positive at any weekly testing after 22 to 24 weeks gestation (sensitivity 76.82%, specificity 58.33%, PPV 66.7%). The presence of fFN was most highly predictive of preterm birth when performed during the 24th to 28th gestational week. Shorter cervical lengths were highly correlated with preterm birth (r = -0.6). An association between bacterial vaginosis and preterm birth was not demonstrated in this sample.

CONCLUSION

Sampling for the presence of fetal fibronectin can be easily accomplished by RNs in labor triage units and by advanced practice nurses in outpatient settings. The identification of fFN, particularly during the 24 to 28 weeks gestational time frame, is highly predictive of preterm birth, and particularly so for women with twin gestations.

Racial disparity in membrane response to infectious stimuli: a possible explanation for observed differences in the incidence of prematurity. Community Award Paper

OBJECTIVE

This study compares the immune responsiveness of amniochorionic membranes (AC) derived from African American (AA) and white (C) women to an infectious stimulus ex vivo.

STUDY DESIGN

AC derived from AA and C women were placed in an organ explant culture for 48 hours and then stimulated with endotoxin. Enzyme-linked immunosorbent assay measured the concentration of matrix metalloproteinase 9 (MMP9), tumor necrosis factor-alpha (TNF-alpha), and soluble TNF receptors (sTNFR1 and sTNFR2) in culture media from stimulated and unstimulated AC.

RESULTS

The C group produced 8-fold more TNF-alpha after stimulation than did the AA group. Both soluble receptor (R1 and R2) production increased in the C group and decreased in the AA group after stimulation. Although the C group-derived membranes produced more MMP9 at rest, a 6-fold increase in MMP9 concentration was seen in the AA group-derived membranes after stimulation. No change in MMP9 concentration was seen after stimulation of the C group-derived membranes.

CONCLUSION

Although the C group produced more TNF, they also produce higher sTNFRs, which may serve a protective role. The increased MMP9 release by the AA group may be suggestive of the greater risk of premature rupture of membranes in the AA group.

Effects of domestic violence on preterm birth and low birth weight

BACKGROUND

Domestic violence is increasingly recognized as a potentially modifiable risk factor for adverse pregnancy outcomes. This study was conducted to evaluate the relationship between abuse during pregnancy or within the last year and low birth weight and preterm birth.

METHODS

From 1997 to 2001, 3149 low income, relatively low-risk pregnant women (82% African-American) participated in this prospective study. The Abuse Assessment Screen, a validated screening tool, which assesses emotional, physical or sexual abuse, injuries due to physical abuse and physical abuse in the index pregnancy, was filled out by 3103 women.

RESULTS

Of the women screened, 26.6% reported emotional abuse, 18.7% reported physical abuse in the past year and 10.3% women reported being beaten, bruised, threatened with a weapon or being permanently injured. Abuse during pregnancy was reported by 5.9% of the women. Low birth weight and preterm birth occurred in 10.9% and 10.2% of the pregnant women, respectively. Logistic regression analyzes indicated that injury due to physical abuse within the past year was significantly associated with both preterm birth [adjusted odds ratio (AOR) = 1.6, 95% confidence interval (CI) = 1.1-2.3] and low birth weight (AOR = 1.8, 95% CI = 1.3-2.5) after adjusting for other covariates. The mean birth weight of infants born to women who were injured due to physical abuse was significantly lower (-75.2 g, p = 0.04) than the mean birth weight of infants of women who were not injured.

CONCLUSION

These results indicate that in our population, injuries resulting from physical abuse are associated with both low birth weight and preterm birth.

Preterm delivery rates in North Carolina: are they really declining among non-Hispanic African Americans?

The preterm delivery rate in North Carolina is consistently higher than the national average. However, recent reports suggest that singleton preterm delivery rates for non-Hispanic Whites are increasing while those for non-Hispanic African Americans are decreasing. To study this pattern further, the authors examined data on singleton non-Hispanic White and non-Hispanic African-American births in 1989 and 1999 by using North Carolina vital statistics data. They found that the frequency of preterm delivery rose 1.1% (8.5% to 9.6%) among non-Hispanic Whites but declined 1.4% (17.9% to 16.5%) among non-Hispanic African Americans over the same time period. For both subgroups, a bimodal distribution of birth weights was apparent among preterm births at 28-31 weeks of gestation. The second peak with its cluster of normal-weight infants was more prominent among non-Hispanic African Americans in 1989 than in 1999. To reduce the potential for bias due to misclassification of infant gestational age, frequencies of preterm delivery of infants who weighed less than 2,500 g were calculated. Unlike the original analysis, this calculation showed that preterm delivery increased for both subgroups. A number of non-Hispanic African-American births classified as preterm were apparently term births mistakenly assigned short gestational ages. Such misclassification was more frequent in 1989 than in 1999, inflating 1989 preterm delivery rates.

Preterm birth among African American and white women: a multilevel analysis of socioeconomic characteristics and cigarette smoking

STUDY OBJECTIVE

Research shows that neighbourhood socioeconomic factors are associated with preterm delivery. This study examined whether cigarette smoking and individual socioeconomic factors modify the effects of neighbourhood factors on preterm delivery.

DESIGN

Case-control study.

SETTING

Moffit Hospital in San Francisco, California.

PARTICIPANTS

417 African American and 1244 white women, including all preterm and a random selection of term deliveries 1980-1990, excluding non-singleton pregnancies, congenital anomolies, induced deliveries, and women transported for special care. US census data from 1980 and 1990 were used to characterise the women's neighbourhoods, defined as census tracts.

RESULTS

Cigarette smoking increased the risk of preterm delivery among both African American (OR=1.77, 95% confidence intervals (CI) (1.12 to 2.79)) and white women (OR=1.25, 95% CI (1.01 to 1.55)). However, cigarette smoking did not attenuate or modify the association of neighbourhood factors with preterm delivery. Among African American women, having public insurance modified the relation between neighbourhood unemployment and preterm delivery; among women without public insurance, the risk of preterm delivery was low in areas with low unemployment and high in areas with high unemployment, while among women with public insurance the risk of preterm delivery was highest at low levels of neighbourhood unemployment.

CONCLUSIONS

Cigarette smoking was associated with preterm delivery, especially among African Americans. Adverse neighbourhood conditions had an influence on preterm delivery beyond that of cigarette smoking. The effects of some neighbourhood characteristics were different depending on individual socioeconomic status. Examining socioeconomic and behavioural/biological risk factors together may increase understanding of the complex causes of preterm delivery.

The interrelationship of maternal stress, endocrine factors and inflammation on gestational length

Preterm birth rates continue to rise in the United States despite the advent of tocolytic agents and the identification of risk factors for preterm birth, such as vaginal infection and a shortened cervix. Although improvement in gestational-age-related survival of preterm infants has occurred as a result of the use of antenatal corticosteroids, neonatal surfactant therapy, and regionalization of perinatal care, there has been no reduction in the incidence of preterm birth. Recently, investigators have appreciated that the etiology of preterm birth is heterogeneous, perhaps accounting for one reason for the failure of current interventions to improve pregnancy outcome. Both abnormal maternal hormonal homeostasis and intrauterine inflammatory responses appear to contribute to a significant proportion of the cases of preterm birth, and the interaction of the maternal endocrine and immunologic systems may contribute to the pathophysiology of this condition. An important modulator of endocrine and immune function is perceived emotional and social stress. Maternal stress has been strongly associated with preterm birth, but the links between maternal stress and resultant aberrations of maternal endocrine and immune function remain difficult to quantify and investigate. However, new insights into the role of perceived maternal stress on gestational length suggest that specific interventions to alleviate stress could contribute to an increase in gestational length and a decrease in the risk for preterm birth. This review addresses the role of maternal stress on the regulation of maternal hormone and inflammatory responses and how aberrations in these systems may lead to preterm birth.

Preterm low birth weight and periodontal disease among African Americans

African Americans consistently experience higher rates of preterm and low birth weight (LBW) deliveries than do whites. LBW and preterm infants are more likely to die before their first birthday and survivors may suffer from a number of health problems. Therefore, identification of modifiable risk factors for preterm deliveries and LBW has considerable public health significance. Pregnant women's poor periodontal healtlh is emerging as one such factor. Maternal clinical periodontal status and bacteriologic and immunologic profiles related to periodontal disease have been associateted with risk of fetal growth and preterm LBW, and periodontal treatment during pregnancy has reduced the incidence of preterm deliveries. This article reviews the literature on the above association and presents data from a previously published prospective study of predominantly African Americans to show that preterm LBW deliveries are associated with higher midtrimester maternal serum antibody levels against Porphyromonas gingivalis.

Sexual intercourse association with asymptomatic bacterial vaginosis and Trichomonas vaginalis treatment in relationship to preterm birth

OBJECTIVE

The purpose of this study was to determine whether sexual intercourse was associated with the treatment efficacy or the incidence of preterm birth in two large randomized trials in which metronidazole treatment of bacterial vaginosis or Trichomonas vaginalis did not reduce preterm birth.

STUDY DESIGN

Secondary analysis of two multicenter, double-blind, placebo-controlled trials in which women with asymptomatic bacterial vaginosis on Gram stain or asymptomatic T vaginalis on culture were randomized at 16 to 23 weeks of gestation to metronidazole or placebo. In both studies, women took 2 g of metronidazole or placebo in the presence of a nurse (first dose) and were given a second dose to take 48 hours later. This regimen was repeated (third and fourth doses) at 24 to 29 weeks. At the time of the third dose, bacterial vaginosis and T vaginalis specimens were collected again. Patients who were randomly selected to receive metronidazole were analyzed for bacterial vaginosis and T vaginalis at 24 to 29 weeks and for preterm birth of <37 weeks of gestation, according to intercourse between first and second doses and between the second and third doses. Continuous variables were compared with the use of the Wilcoxon rank-sum test; categoric variables were compared with the use of the chi(2 ) test, Fisher exact test, or the Mantel-Haenzel test of trend.

RESULTS

Sexual intercourse between the first and second doses or between the second and third doses did not influence the incidence of bacterial vaginosis (18% vs 24%; relative risk, 0.7; 95% CI, 0.5-1.1; and 23% vs 20%; relative risk, 1.2; 95% CI, 0.9-1.6, respectively) or T vaginalis (4% vs 8%; relative risk, 0.5; 95% CI, 0.1-3.6; and 5% vs 10%; relative risk, 0.5; 95% CI, 0.2-1.1; respectively) at 24 to 29 weeks of gestation compared with no intercourse. In the T vaginalis trial, sexual intercourse between the first and second doses or between the second and third doses did not influence the incidence of preterm birth (13% vs 17%; relative risk, 0.8; 95% CI, 0.3-2.1; and 16% vs 17%; relative risk, 1.0; 95% CI, 0.6-1.6; respectively) compared with no intercourse. In the bacterial vaginosis trial, although sexual intercourse between the first and second doses did not influence the incidence of preterm birth (11% vs 12%; relative risk, 0.9; 95 % CI, 0.6-1.5), sexual intercourse between the second and third doses was associated with a reduction in the incidence of preterm birth (10% vs 16%; relative risk, 0.6; 95% CI, 0.4-0.9) compared with no intercourse.

CONCLUSION

Sexual intercourse was associated with neither the efficacy of metronidazole treatment of bacterial vaginosis or T vaginalis nor with the incidence of preterm birth. In the bacterial vaginosis study, intercourse between the second and third doses had a negative association with preterm birth.

Perceptions of racial discrimination and the risk of preterm birth

BACKGROUND

Because racial discrimination might contribute to their excess of preterm births, we assessed experiences of racism in relation to preterm birth among African-American women.

METHODS

We used data from the Black Women's Health Study, a follow-up study of African-American women begun in 1995. Data on subsequent singleton births were obtained using follow-up questionnaires in 1997 and 1999; nine questions about experiences of racism were asked in 1997. We compared mothers of 422 babies born 3 or more weeks early (because of premature labor for unknown reasons or rupture of membranes) with mothers of 4544 babies of longer gestation. We used generalized estimating equation models to estimate odds ratios (ORs) for preterm birth, controlling potential confounders.

RESULTS

The adjusted ORs for preterm birth were 1.3 (95% confidence interval [CI] = 1.1-1.6) for women who reported unfair treatment on the job and 1.4 (1.0-1.9) for women who reported that people acted afraid of them at least once a week. Overall ORs for the seven other racism questions were close to 1.0. Among 491 women with </=12 years of education, ORs were 2.0 or greater for four racism variables.

CONCLUSIONS

These data provide some evidence for an increase in preterm birth among women who report experiences of racism, particularly women with lower levels of education.

Parental age difference and adverse perinatal outcomes in the United States

This study was undertaken to examine the relationship between paternal and maternal age differences and adverse perinatal outcomes in the United States. Data were obtained on singleton pregnancies delivering at >or=20 weeks gestation in the United States in 1995-97 from the National Center for Health Statistics data sets. Adverse perinatal outcomes that were evaluated included fetal death rate (>or=20 weeks), preterm delivery <37 weeks and small-for-gestational-age (SGA) births (birthweight <10th centile for gestational age and corrected for sex). Age difference was defined as paternal minus maternal age. The analysis included 8995274 pregnancies (11.3% blacks, 88.7% whites). An increase in fetal death rate, preterm delivery and SGA births was noted among white women who were older than their male partners. For black mothers older than their partners, there was an increase in fetal death rate when the women were <20 years old, but a decrease in fetal death rate when >35 years old. Neither rates of preterm delivery nor SGA births were increased much for black women with varying parental age differences. This demonstrates that race and maternal age both contribute to the effects of parental age difference on adverse perinatal outcomes.

Neighborhood socioeconomic status, maternal race and preterm delivery: a case-control study

PURPOSE

To explore associations between neighborhood socioeconomic context and preterm delivery, independent of maternal and family socioeconomic status, in African-American and white women.

METHODS

A case-control study of African-American (n = 417) and white (n = 1244) women delivering infants at the University of California, San Francisco's Moffitt Hospital, between 1980 and 1990.

RESULTS

Neighborhood socioeconomic contexts were associated with preterm delivery but associations were non-linear and varied with race/ethnicity. For African-American women, living in a neighborhood with either high or low median household income was associated with an increased risk of spontaneous preterm delivery, as was living in a neighborhood with large increases or decreases in the proportion of African-American residents during the study decade. Residence in neighborhoods with high and low rates of male unemployment was associated with a decreased risk of preterm delivery. Among white women only large positive and negative changes in neighborhood male unemployment were associated with risk of preterm delivery.

CONCLUSIONS

Neighborhood factors and changes in neighborhoods over time are related to preterm delivery, although the mechanisms linking local environments to maternal risk remain to be specified.

The risk of preterm delivery in women from different ethnic groups

OBJECTIVE

To examine whether routinely measured variables explained the increased risk of preterm delivery in some UK ethnic groups.

DESIGN

Cross sectional study of deliveries recorded in the Child Health Record System.

SETTING

North Birmingham, UK.

POPULATION

All North Birmingham women delivering singletons, 1994-1997 inclusive.

METHOD

Logistic regression.

MAIN OUTCOME MEASURES

Odds ratio (OR) and 95% confidence interval (CI) for preterm delivery, defined as less than 37 weeks, less than 34 weeks and less than 28 weeks, unadjusted and adjusted for maternal age, an area-based socio-economic status measure, and marital status, year of birth, fetal sex and past obstetric history.

RESULTS

For Afro-Caribbean women, the ORs (95% CIs) were: for delivery less than 37 weeks, 1.44 (1.26-1.64) unadjusted and 1.22 (1.07-1.41) adjusted; for delivery less than 34 weeks, 1.55 (1.25-1.92) unadjusted and 1.29 (1.02-1.61) adjusted; for delivery less than 28 weeks, 1.66 (1.08-2.55) unadjusted and 1.32 (0.84-2.06) adjusted. For African women, the risk of delivery less than 37 weeks was not significantly raised; for delivery less than 34 weeks, the OR (95% CI) was 1.88 (0.99-3.58) unadjusted and 1.78 (0.93-3.40) adjusted; for delivery less than 28 weeks, the OR (95% CI) was 4.02 (1.60-10.12) unadjusted and 4.10 (1.66-10.16) adjusted. In Afro-Caribbeans, deprivation and marital status explained the differences between the unadjusted and adjusted ORs. There was a linear relation between deprivation and preterm delivery for all ethnic groups, except for Asians.

CONCLUSIONS

Factors associated with deprivation and marital status explain about half of the excess of preterm births in Afro-Caribbeans, but not Africans. The risk of preterm delivery might not be related to deprivation in Asians.

Polymorphism in the interleukin-1 gene complex and spontaneous preterm delivery

OBJECTIVE

We examined the association between preterm delivery and polymorphisms at position +3953 of the interleukin-1 beta gene (IL1B+3953) and in intron 2 of the interleukin-1 receptor antagonist gene (IL1RN).

STUDY DESIGN

This was a case-control study that involved 52 pregnancies that resulted in spontaneous preterm delivery before 34 weeks of gestation and 197 pregnancies that resulted in birth at term. Polymorphisms were determined by polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

Homozygous carriage of IL1B+3953 allele 1 by fetuses of African descent was associated with a risk of preterm delivery (P =.033). Fetuses of Hispanic descent that carried IL1RN allele 2 were found to be at an increased risk for preterm premature rupture of membranes and subsequent preterm delivery(P =.021; odds ratio, 6.5; 95% CI, 1.25-37.7).

CONCLUSION

There are associations of spontaneous preterm delivery with the fetal carriage of IL1B+3953*1 and IL1RN*2 alleles in African and Hispanic populations, respectively.

Is vaginal douching associated with preterm delivery?

BACKGROUND

To examine the hypothesized association between vaginal douching and preterm delivery, we conducted a study among women in a managed care organization in Atlanta, GA.

METHODS

We drew a stratified random sample of 262 preterm (20-36 weeks' gestation) and 804 term deliveries that occurred between January 1996 and April 1997. Data were collected from telephone interviews and medical records. We used proportional hazards regression to compute gestation-specific conditional probabilities of delivery. The risk of preterm delivery associated with douching was examined, adjusted for potential confounders.

RESULTS

Douching during pregnancy increased the overall risk of preterm delivery (hazard ratio = 1.9, 95% confidence interval = 1.0-3.7).

CONCLUSIONS

Further research to clarify the relation between douching and preterm delivery should pay particular attention to the role of vaginal infections.

Socioeconomic status and preterm birth: New Zealand trends, 1980 to 1999

BACKGROUND

While a number of countries have reported rising preterm birth rates over the past two decades, none has examined the effects of socioeconomic status on preterm birth at a national level.

AIM

To document the changing incidence of preterm birth in New Zealand over the past 20 years and to determine whether particular socioeconomic or ethnic subsections of the population have contributed disproportionately to the changes seen.

METHODS

Birth registration data routinely available from the New Zealand Health Information Service were analysed for the period 1980-99. Information for a total of 1 079 478 singleton live births was linked by Domicile Code to the New Zealand Deprivation Index, a small area index of deprivation.

RESULTS

Singleton preterm birth rates rose by 37.2% during the 20 year period, from 4.3% in 1980 to 5.9% in 1999. Rates increased by 71.9% among those living in the most affluent areas, but by only 3.5% among those living in the most deprived areas, resulting in the disappearance of a socioeconomic gradient in preterm birth that had existed during the early 1980s.

CONCLUSIONS

This study challenges traditional thinking on the associations between socioeconomic status and preterm birth. Further research is necessary if the changes that have occurred in New Zealand over the past 20 years are to be fully understood.

Smoking and pregnancy outcome among African-American and white women in central North Carolina

Despite extensive research on tobacco smoking during pregnancy, few studies address risks among African-American and white women, groups that differ in brand preference and smoking habits. The Pregnancy, Infection, and Nutrition Study is a prospective cohort study that included 2,418 women with detailed information on smoking during pregnancy, including brand, number of cigarettes per day, and changes during pregnancy. We analyzed risk of preterm birth (<37 and <34 weeks' gestation) and small-for-gestational-age deliveries in relation to tobacco use. Pregnant African-American smokers differed markedly from whites in brand preference (95% vs 26% smoked menthol cigarettes) and number of cigarettes per day (1% of African-Americans and 12% of whites smoked 20+ cigarettes per day). Smoking was not related to risk of preterm birth overall, but cotinine measured at the time of delivery was (adjusted odds ratio = 2.2, 95% confidence interval = 1.1-4.5). A clear association and dose-response gradient was present for risk of fetal growth restriction (risk ratio for 20+ cigarettes/day = 2.4, 95% confidence interval = 1.4-4.0). Associations of tobacco use with preterm premature rupture of amniotic membrane resulting in preterm birth were notably stronger than the associations with other types of preterm birth.

Rates of preterm delivery among Black women and White women in the United States over two decades: an age-period-cohort analysis

The authors assessed the influence of age, period, and cohort effects on rates of preterm delivery in the United States. Rates of preterm delivery for singleton births (<37 weeks) in seven age groups (15-19, 20-24,., 45-49 years), five periods (1975, 1980, 1985, 1990, 1995), and 11 maternal birth cohorts (1926-1930, 1931-1935,., 1976-1980) were examined. Over the 20-year study interval, preterm delivery increased by 3.6% among Blacks (from 15.5% in 1975 to 16.0% in 1995) and by 22.3% among Whites (from 6.9% to 8.4%). Among Black primigravid women, rates of preterm delivery increased from 1975 to 1990 and began to decline thereafter; among Whites, the rates increased between 1975 and 1995. In Blacks, women aged 25-29 years had the lowest rates for the first and second births, and women aged 30-34 years had the lowest rate for subsequent births. In Whites, the age groups with the lowest preterm delivery rates were 20-24 years for first births and 25-29 years for subsequent births. Cohort-specific rates of preterm delivery remained fairly constant across age strata and periods for Whites, but a small trend was apparent for Blacks aged 30-44 years. The consistency of the observed age effects across periods and cohorts suggests that the age effect is partly due to biologic factors. The presence of period effects might be linked to the increased survival of premature infants or to increased viability among births occurring at lower lengths of gestation.

Race, clinical factors and pre-term birth in a low-income urban setting

While infant mortality rates have declined for both White and African-American populations, the perennial two-fold excess in risk for African Americans remains unchanged, and indeed, may have increased since 1985. One potential explanation for the excess risk in African Americans might be racial differences in maternal clinical risk factors, such as prior pregnancy history and pregnancy complications. This paper examines the contributions of such clinical indicators to racial differences in pre-term delivery in a study sample of urban, low-income women, aged 18 to 43 years.

METHODS

Study participants were enrolled during their first prenatal care visit at one of four hospital-based, prenatal care clinics in Baltimore City. Medical history and pregnancy outcome data were abstracted from clinical records. Multiple logistic regression models were used to assess the independent relationship between race and pre-term birth, after controlling for clinical factors.

RESULTS

Without adjustment for clinical risk factors, African-American women were 1.8 times more likely than White women to have a pre-term birth outcome (95% confidence interval 1.20-2.78). After statistical adjustment for the clinical variables, however, the association between race and pre-term birth was diminished (OR = 1.64, 95% confidence interval: 0.99-2.72). Moreover, the associations between certain clinical risks and pre-term birth were stronger for African-American than White women.

CONCLUSION

These results suggest that attention to clinical risk factors among African-American women may be an important avenue for reducing Black/White racial disparities in pre-term birth.

Maternal experiences of racism and violence as predictors of preterm birth: rationale and study design

Chronic psychological stress may raise the risk of preterm delivery by raising levels of placental corticotropin-releasing hormone (CRH). Women who have been the targets of racism or personal violence may be at particularly high risk of preterm delivery. The aims of this study are to examine the extent to which: (1) maternal experiences of racism or violence in childhood, adulthood, or pregnancy are associated with the risk of preterm birth; (2) CRH levels are prospectively associated with risk of preterm birth; and (3) CRH levels are associated with past and current maternal experiences of racism or violence. We have begun to examine these questions among women enrolled in Project Viva, a Boston-based longitudinal study of 6000 pregnant women and their children.

Second trimester corticotropin-releasing hormone levels in relation to preterm delivery and ethnicity

OBJECTIVE

To assess the relationship between maternal corticotropin-releasing hormone (CRH) levels in second trimester sera, and the risk of preterm delivery in an ethnically heterogeneous sample of pregnant women.

METHODS

This nested case-control study included two case groups (97 women who delivered before 35 weeks' gestation, 144 who delivered at 35--36 weeks' gestation), and a control group (244 women who delivered at or after 37 weeks' gestation) frequency matched by ethnicity (black, white) and by alpha-fetoprotein levels (normal, unexplained high). Corticotropin-releasing hormone was evaluated in stored maternal sera collected at 15--19 weeks' gestation from cases and controls.

RESULTS

Delivery before 35 weeks' gestation was associated positively with a second trimester, ethnic-specific CRH above 1.5 multiples of the median in white women [odds ratio (OR) 2.3, 95% confidence interval (CI) 1.1, 5.1] and black women (OR 5.0, 95% CI 1.8, 13.3). Sensitivity was 29% in whites and 41% in blacks; specificity was 84% in whites and 80% in blacks. We estimated the positive and negative predictive values to be 6% and 97%, respectively, in white women, and 16% and 93%, respectively, in black women. It was also noted that, within case and control groups, black women had consistently lower CRH levels than white women.

CONCLUSION

Factors that lead to a premature increase in placental CRH production and are associated with an increased risk of preterm birth are evident as early as 15--19 weeks' pregnancy. When considering potential links between stressors, placental changes, CRH levels, and preterm birth, it might be important to stratify or adjust for ethnicity.

The contribution of maternal smoking to preterm birth, small for gestational age and low birthweight among Aboriginal and non-Aboriginal births in South Australia

OBJECTIVES

To determine the contribution of maternal smoking to preterm birth (< 37 weeks' gestation), small for gestational age (SGA, birthweight < 10th percentile for gestational age) and low birthweight (< 2500 g) among Aboriginal and non-Aboriginal births in South Australia.

DESIGN

Retrospective cohort analysis of population-based perinatal data.

SETTING

The State of South Australia, population 1.5 million.

PARTICIPANTS

36059 women (of whom 851 were Aboriginal women) who had singleton births in 1998-1999.

MAIN OUTCOME MEASURES

Relative risks and population-attributable risks of preterm birth, SGA and low birthweight from smoking in the second half of pregnancy, by age and Aboriginality.

RESULTS

Aboriginal women had a higher rate of smoking in pregnancy than non-Aboriginal women (57.8% v 24.0% at the first antenatal visit) and high rates for all age groups, while the rates decreased with age among non-Aboriginal women. Heavy smoking increased with age, and Aboriginal women were heavier smokers. Women who smoked had elevated relative risks of preterm birth (1.64), SGA (2.28) and low birthweight (2.52), and all these showed a dose-response relationship. Among Aboriginal (versus non-Aboriginal) births, population-attributable risks were significantly higher for SGA (48% v 21%, and 59% for births to Aboriginal teenagers), low birthweight (35% v 23%) and preterm birth (20% v 11%).

CONCLUSIONS

Health promotion programs, with a focus on smoking cessation and reducing uptake of smoking, need to be implemented in an appropriate cultural context, especially among young Aboriginal women. Such a program is being developed in South Australia.

Variation in vaginal breech delivery rates by hospital type

OBJECTIVE

To relate vaginal breech delivery rates to the following hospital types: public, health maintenance organization, private teaching, or private nonteaching.

METHODS

In a retrospective study using administrative discharge data from Los Angeles County, California, we calculated the vaginal breech delivery rates of singleton breech deliveries during calendar years 1988 and 1991.

RESULTS

Ten thousand four hundred breech deliveries were identified, 8988 (86.4%) term and 1412 (13.6%) preterm. Twelve percent (1252 of 10,400) were vaginal deliveries (10.1% term and 24.5% preterm). Term vaginal breech deliveries varied by hospital type and were more frequent in public hospitals (28.4%, 95% confidence interval [CI] 26.1%, 30.7%) and less frequent in private nonteaching hospitals (5.4%, 95% CI 4.8%, 5.9%). Term vaginal deliveries were 2.4 to 11.3 times more likely among black women and 1.3 to 6.3 times more likely for Hispanic women across all hospital types, compared with white women in private nonteaching hospitals. There was no difference in the proportion of preterm vaginal breech deliveries by hospital type (mean 24.5%). However, with the exception of public hospitals, the proportion of vaginal breech deliveries for both term and preterm deliveries varied significantly by ethnicity.

CONCLUSION

The use of vaginal breech delivery varied by hospital type and patient ethnicity. Within private teaching and nonteaching hospitals, vaginal breech delivery was more likely for black women than for women of other ethnic groups. Further study is needed to understand the hospital policies or organizational factors, as well as the patient-related sociocultural and clinical factors, that contribute to those differences.

The association of life events to gestational age at delivery among low-income, urban, African American women

OBJECTIVE

To investigate the relationship of life events stress to gestational age at delivery for a cohort of low income, African-American women.

STUDY DESIGN

Four hundred seventy-two African-American women from three public prenatal clinics were interviewed about life events, emotional support, and health habits. Pregnancy and birth data were collected from a clinical data base. The contribution of life events stress and other study variables to length of pregnancy was determined using linear regression models for primiparous and multiparous women.

RESULTS

Frequency of life events was not related to gestational age at delivery, directly or indirectly. An unexpected finding was that women who experienced a death of a mother or sister delivered on average 4.6 weeks earlier than other women in the study. Complications of pregnancy also explained lower gestational age for both primiparas and multiparas.

CONCLUSION

Among low-income women, the acute stressor of losing a mother or sister during pregnancy was significantly related to shorter pregnancy, although total number of events was not.

Stress, pre-term labour and birth outcomes

Stress, pre-term labour and birth outcomes Preliminary studies have suggested that stress may be associated with the onset, treatment and outcomes of pre-term labour; however, a systematic comparison of the stress of women with and without pre-term labour has not been reported. Therefore, the purpose of this exploratory study was to compare the stress (daily hassles and mood states) and birth outcomes of black and white women who experienced pre-term labour (PTL) during pregnancy with those who did not. The convenience sample consisted of 35 pregnant women hospitalized in 1996-1997 for the treatment of PTL (24-35 weeks gestation) and 35 controls matched on age, race, parity, gestational age and method of hospital payment. Women in the PTL group had significantly higher tension-anxiety and depression-dejection on the Profile of Mood States (POMS), lower mean birthweight and mean gestational age, and a higher percentage of babies born <37 weeks and weighing 2500 g or less. Black women in the PTL group and white women in the control group had significantly higher scores on the fatigue sub-scale of the POMS and the work and future security sub-scales of the Daily Hassles Scale. Women in the PTL group whose babies weighed 2500 g or less had significantly higher scores on the health, inner concern and financial responsibility sub-scales of the Daily Hassles Scale. The findings from this study indicate the need for further exploration of the interaction of race and stress in understanding and preventing PTL and low birthweight and the need to examine the role of social support in preventing pre-term birth after an episode of PTL.