Correlates of experiencing life events just before or during pregnancy.

This study evaluates the prevalence of selected life events around the time of pregnancy, examining changes in the prevalence of these events, and identifying maternal characteristics associated with these events. We used data from the Pregnancy Risk Assessment Monitoring System (PRAMS) to examine 18 stressful life events among women who recently gave birth and to identify maternal characteristics associated with these events. PRAMS is a mail sample survey with telephone follow-up for non-respondents. Sixty-four percent of women experienced at least one event. The prevalence of specific events ranged from 0.4 to 30%. Women who experienced events differed from those who did not. Most notably, women of low socioeconomic status (SES) were much more likely to experience stressful life events. These events were also associated with other demographic and behavioral characteristics after controlling for SES. These results have implications for interpreting studies of stressful life events. The strong associations with SES highlight the importance of controlling for SES in studies of life events and health, and of considering differences in SES when interpreting these studies.

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

UNLABELLED: 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.

Prepregnancy body mass index and pregnancy weight gain: associations with preterm delivery. The NMIHS Collaborative Study Group.

OBJECTIVE: To examine associations between rate of pregnancy weight gain and preterm delivery among women of varying prepregnancy body mass indices (BMI). METHODS: Subjects were 3511 mother-infant pairs from the 1988 National Maternal and Infant Health Survey. Prenatal weight measured between 14 and 28 weeks' gestation was used to calculate rate of pregnancy weight gain for each woman. Weight gain (lb/week) was categorized as low (under 0.5), average (0.5-1.5), or high (above 1.5). Prepregnancy BMI was calculated as weight divided by height in (kg/m(2)) and categorized as low (under 19.8), average (19.8-26.0), and high (above 26). Delivery before 37 weeks' gestation was considered preterm. Associations between BMI, weight gain, and preterm delivery were examined before and after exclusion of medically indicated preterm deliveries and pregnancies complicated by maternal medical conditions potentially related to weight gain or fetal growth restriction. Associations were expressed as odds ratios (OR) adjusted for several potential confounding factors. RESULTS: Women with low pregnancy weight gain were at increased risk of preterm delivery. The magnitude of risk varied according to a woman's prepregnancy BMI. After all exclusions and adjustments for confounders, ORs, and 95% confidence intervals (CI) for low pregnancy weight gain were 6.7 (1.1, 40.6) for underweight women, 3.6 (1.6, 8.0) for average-weight women, and 1.6 (0.7, 3.5) for overweight women compared with average-weight women with average pregnancy weight gain. CONCLUSIONS: Low weight gain in pregnancy was associated with increased risk of preterm delivery, particularly if women were underweight or of average weight before pregnancy.

Are interpregnancy intervals between consecutive live births among black women associated with infant birth weight?

OBJECTIVES: The purpose of this study was to determine whether the length of interpregnancy intervals between consecutive live births among Black women had any significant effect on mean birth weight as had previously been reported in another study. DESIGN: We examined a sample (1,048 women, 66% of study participants) from a study of non-Hispanic Black women whose infants were born at a large, inner-city, public hospital in Georgia from October 1988 through August 1990. Data were evaluated for the 494 women whose current and immediately previous pregnancies ended in the birth of a live infant weighing 500 grams or more. METHODS: Linear regression and analysis of covariance models were developed. RESULTS: The median interpregnancy interval was 15 months (range 1 to 207 months), with 19 (4%) of the women having intervals of less than 3 months. After adjustment for parity, gestational age (in weeks), and smoking status, the mean birth weight associated with an interpregnancy interval of three or more months was 3,106 grams, 215 grams greater than that for an interval of less than three months (P = .06). CONCLUSIONS: Although longer birth spacing has been associated with certain positive social and health effects, the population attributable effect on infant birth weight may not be very significant.

Chemical hair treatments and adverse pregnancy outcome among Black women in central North Carolina.

Several studies suggest that toxic chemicals in hair products may be absorbed through the scalp in sufficient amounts to increase the risks of adverse health effects in women or their infants. This case-control study of 525 Black women from three counties in North Carolina who had delivered a singleton, liveborn infant examined whether exposure to chemicals used in hair straightening and curling increased the odds that the infant was preterm or low birth weight. Cases consisted of 188 preterm and 156 low birth weight births (for 123 women, their infant was both low birth weight and preterm). Controls were 304 women who delivered term and normal birth weight infants. Women who used a chemical hair straightener at any time during pregnancy or within 3 months prior to conception had an adjusted odds ratios (OR) of 0.7 (95% confidence interval (CI) 0.4-1.1) for preterm birth and 0.6 (95% CI 0.4-1.1) for low birth weight. Exposure to chemical curl products was also not associated with preterm delivery (adjusted OR = 0.9, 95% CI 0.5-1.8) or low birth weight (adjusted OR = 1.0, 95% CI 0.5-1.9). Despite this failure to find an association, continued search for risk factors to which Black women are uniquely exposed is warranted.

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

OBJECTIVES: To determine if the association between race and preterm delivery would persist when preterm delivery was partitioned into two etiologic pathways. METHODS: We evaluated perinatal and obstetrical data from the 1988 National Maternal and Infant Health Survey and classified preterm delivery as spontaneous or medically indicated. Discrete proportional hazard models were fit to assess the risk of preterm delivery for Black women compared with White women adjusting for potential demographic and behavioral confounding variables. RESULTS: Preterm delivery occurred among 17.4% of Black births and 6.7% of White births with a Black versus White unadjusted hazard ratio (HR) of 2.8 (95% CI = 2.4-3.3). The adjusted HR for a medically indicated preterm delivery showed no racial difference in risk (HR = 1.0, 95% CI = 0.4-2.6). However, for spontaneous preterm delivery between 20 and 28 weeks gestation, the Black versus White adjusted hazard ratio (HR) was 4.9 (95% CI = 3.4-7.1). CONCLUSIONS: Although we found an increased unadjusted HR for preterm delivery among Black women compared with White women, the nearly fivefold increase in adjusted HR for the extremely preterm births and the absence of a difference for medically indicated preterm delivery was unexpected. Given the differences in the risks of preterm birth between Black and White women, we recommend to continue examining risk factors for preterm delivery after separating spontaneous from medically indicated preterm birth and subdividing preterm delivery by gestational age to shed light on the reasons for the racial disparity.

Risk factors for preterm birth subtypes.

To assess epidemiologic risk factors for preterm birth subcategories in an urban population, we undertook a study of 31,107 singleton livebirths that took place at Mount Sinai Hospital in New York City between 1986 and 1994. We subdivided the preterm births into preterm premature rupture of the membranes, preterm labor, and medically induced births. We obtained information regarding the preterm subtypes and their epidemiologic risk factors from a computerized perinatal database. Adjusted odds ratios showed an increased risk for all three preterm birth subtypes in women who were black (1.9 for preterm premature rupture of membranes, 2.1 for preterm labor, and 1.7 for medically induced births) or Hispanic (1.7 for preterm premature rupture of membranes, 1.9 for preterm labor, and 1.6 for medically induced births), those who had had a previous preterm birth (3.2 for preterm premature rupture of membranes, 4.5 for preterm labor, and 3.3 for medically induced births), those who began prenatal care after the first trimester ( 1.4 for preterm premature rupture of membranes, 1.3 for preterm labor, and 1.3 for medically induced births), women who had been exposed to diethylstilbestrol in utero (3.1 for preterm premature rupture of membranes, 4.1 for preterm labor, and 3.7 for medically induced births), patients with preexisting diabetes mellitus (2.2 for preterm premature rupture of membranes, 2.4 for preterm labor, and 9.5 for medically induced births), and those with antepartum bleeding (2.8 for preterm premature rupture of membranes, 3.6 for preterm labor, and 3.7 for medically induced births). Other sociodemographic, constitutional, life-style, and obstetrical characteristics differed across the groups. Variation in some of the risk factors among the preterm subtypes implies that epidemiologic assessment of the more specific outcomes would be advisable.

Quality assessment of fetal death records in Georgia: a method for improvement.

OBJECTIVES: Although more fetal deaths than neonatal deaths occur, routinely collected fetal death data are seldom used for perinatal epidemiologic research because of data quality concerns. We developed a strategy for identifying and correcting errors in birthweight and gestational age in fetal death records. METHODS: Using data from Georgia for 1989 and 1990, we detected singleton fetal death records having improbable or missing birthweight or gestational age by comparing these values with referent values. To verify the questionable values, we contacted 100 reporting hospitals in 1992. RESULTS: In 817 of 2226 records, values were either improbable (60.1%) or missing (39.9%). We were able to contact the hospitals to verify data for 716 (88%) of these records. Verification resulted in corrections to 405 (57%) records, and 48% of unreported birthweights were obtained. CONCLUSIONS: Many errors in recorded gestational age and birthweight were identified by this method. Rather than deleting or inputting problem data for analyses, researchers should consider efforts to verify them. Efforts to improve this information should include improved reporting, strict quality assurance, and procedures for routine verification and correction of records.

Corticotropin-releasing factor and its binding protein: maternal serum levels in term and preterm deliveries.

OBJECTIVE: The primary objective of this investigation was to evaluate whether maternal serum corticotropin-releasing factor levels during pregnancy were predictive of spontaneous preterm delivery. STUDY DESIGN: Maternal serum levels of corticotropin-releasing factor and its binding protein were measured from 20 weeks of gestation in a cross-sectional study of 396 asymptomatic women at high risk for preterm delivery. RESULTS: Gestational age-specific corticotropin-releasing factor levels were not consistently or substantially increased for preterm compared with term deliveries, whether preterm delivery was due to preterm labor or preterm premature rupture of membranes. The binding protein for corticotropin-releasing factor did not vary according to gestational age until term, when it dropped substantially. CONCLUSION: Serum corticotropin-releasing factor levels do not appear to be an important predictor of preterm birth in asymptomatic patients who subsequently have either preterm labor or preterm premature rupture of membranes. Nevertheless, the drop in the corticotropin-releasing factor binding protein level at term suggests that the bioavailability of corticotropin-releasing factor increases as parturition approaches.