History of weight cycling and weight changes during and after pregnancy

s of papers presented at the Fourteenth Annual Meeting, Toronto, Ontario, Canada, June 2001 *denotes person presenting the paper 1997 estimates for each stratum were adjusted by these differences, and a new adjusted 1997 estimate was produced using the 1997 population distribution for each stratum. Results. The first method resulted in an 18.6% difference between asthma prevalence estimates from the 1988 core NHIS and CHS (5.1% vs. 4.3%). Simply inflating the 1997 asthma prevalence estimate of 5.5% by 18.6% yielded an adjusted estimate of 6.5%. The second stratification method produced an adjusted 1997 asthma prevalence estimate of 7.3%. Conclusion. The redesigned NHIS likely produces lower asthma prevalence estimates than the previous NHIS. Adjusting the 1997 estimate to compensate for the redesign suggests that childhood asthma prevalence has plateaued since 1995, not declined. Secular trends in singleton small-for-gestationalage births in blacks and whites in the US CV Ananth*, K Demissie, MS Kramer, AM Vintzileos (Department of Obstetrics, Gynecology and Reproductive Sciences, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, NJ, USA) Objective. To evaluate secular trends in singleton preterm (28–36 weeks) and term (37–41 weeks) small-for-gestational-age (SGA) births, and to estimate the relative contributions of potential determinants of SGA births, separately among blacks and whites. Design. The authors performed a population-based, cohort study comprising blacks (n = 1084 935) and whites (n = 5403 858) that delivered singleton live births in the US in 1989 and 1998. Changes in rates of SGA births (defined as sex-specific birthweight below the 10th centile for gestational age, based on 1989 US births) before and after adjustment for demographic, behavioral determinants and medical and obstetrical complications of current pregnancy. Results. Preterm SGA birth rates among whites increased from 8.5% in 1989 to 9.3% in 1998, a relative increase of 9.4%. Comparable rates among blacks for 1989 and 1998 were 10.5% and 12.4%, respectively, a relative increase of 18.5%. Among term births, the SGA rates declined by 8.1% in whites (9.8% in 1989 and 9.0% in 1998) and by 11.0% among blacks (19.5% in 1989 and 17.3% in 1998). When sequentially adjusted for potential determinants by multivariable logistic regression, the increase in preterm SGA rates were partly explained by pregnancy-induced hypertension and, to a lesser extent, by unmarried status. None of the potential determinants, however, significantly accounted for the decline in term SGA rates. Conclusions. A secular increase in the rate of preterm SGA births in the US and a decline among term SGA births was apparent. These results underscore how little is known about the causes of the observed trends. The importance of these trends on the risks of fetal and neonatal mortality also remains largely unexplored. The effect of overweight and race on age of menarche in a representative survey of US girls SE Anderson*, GE Dallal, A Must (Tufts University, Boston, MA, USA) Despite widespread belief in a trend toward earlier ages at menarche in the US, it is unclear if the evidence justifies speculation about possible environmental causes of early puberty. Previous studies were not representative of the US population and did not account for body weight, a known factor in maturational timing. The authors examined the relationship between weight, race, and menarcheal status in girls ages 11–14 in the National Health and Nutrition Examination Survey III (1988–94) and compared the results to the National Health Examination Survey (1963–70) where the median age at menarche was 12.8 years. A logit model was used to calculate median age at menarche, overall and by race, based on the weighted proportions of girls who were menarcheal at each age. The median age at menarche in NHANES III was 12.6 (95% confidence interval [CI]: 12.0, 13.1), 12.1 (95%CI: 11.9, 12.3) for Blacks, and 12.7 (95%CI: 11.7, 13.5) for Whites. The prevalence of overweight, defined as a body mass index (BMI) above the 85th percentile based on the CDC growth charts, was 29.9% overall, 29.3% for Whites, and 35.6% for Blacks. High BMI was associated with earlier age at menarche. The median age at menarche for girls with a BMI above the 85th percentile was 12.2 years (95%CI: 11.0, 13.0), and was 12.7 years (95%CI: 12.2, 13.2) for girls with a BMI below the 85th percentile. In a multiple logistic regression model using SUDAAN, overweight and Black race were independently associated with increased likelihood of reaching menarche at a given age: OR = 2.3 (95%CI: 1.3, 4.0) overweight; OR = 2.3 (95%CI: 1.2, 4.4) Black. There was no evidence for a race by overweight interaction (P = 0.41). These findings suggest that any decrease in age at menarche in the US is likely due to the increased prevalence of childhood obesity. Adverse outcomes in pregnancies complicated by early vaginal bleeding M Arafa*, MA Fataah, H Abou Zeid, A El-Kouly (Department of Epidemiology, High Institute of Public Health, University of Alexandria, Alexandria, Egypt) Objectives. To assess the perinatal risk of deliveries complicated by light and heavy bleeding, trying to predict the high-risk pregnancies. To evaluate the association between bleeding and perinatal complications in the presence of other confounders. Methods. A case-control, hospital-based study was conducted in the two major obstetric hospitals in Alexandria where women were interviewed during their postpartum stay through 1998. A total of 1503 singleton deliveries, of whom 159 (10.6%) reported bleeding, 101 (63.5%) during the first trimester and 58 (36.5%) during the second. The remaining 1344 women served as controls. Initially, contingency c tests were used to explore the association between bleeding and outcomes, then logistic regression models were used to control for other confounders. Results. Bleeding was more frequent in women of more advanced age (>33 years), with a history of LBW, previous miscarriage and low social class. Suboptimal outcomes (LBW, preterm deliveries, perinatal death and SGA) occurred more often in women reporting bleeding than in those who never bled, and the risk was significantly increased with second trimester bleeding after control for confounders. Logistic regression revealed an interaction among bleeding, interpregnancy interval, and outcomes in that the risk of LBW, preterm, and neonatal death were significantly decreased when the interval was taken into consideration. ConA2 Society for Pediatric and Perinatal Epidemiologic Research © Blackwell Science Ltd. Paediatric and Perinatal Epidemiology 2001, 15, A1–A38 Society for Pediatric and Perinatal Epidemiologic Research A3 clusion. Early bleeding indicates a poor pregnancy outcome, especially during the second trimester, and the risk of LBW, preterm, and neonatal death decreased with increasing pregnancy interval. Unexamined deaths: perinatal mortality in the United States, 1995–97 WD Barfield*, LM Flowers, JA Martin, S Iyasu,