Does breastfeeding duration decrease child obesity? An instrumental variables analysis.

BACKGROUND: Many studies have documented that breastfeeding is associated with a significant reduction in child obesity risk. However, a persistent problem in this literature is that unobservable confounders may drive the correlations between breastfeeding behaviors and child weight outcomes. OBJECTIVE: This study examines the effect of breastfeeding practices on child weight outcomes at age 2. METHODS: This study relied on population-based data for all births in Oregon in 2009 followed for two years. We used instrumental variables methods to exploit variations in breastfeeding by mothers immediately after delivery and the degree to which hospitals encouraged mothers to breastfeed in order to isolate the effect of breastfeeding practices on child weight outcomes. RESULTS: We found that for every extra week that the child was breastfed, the likelihood of the child being obese at age 2 declined by 0.82% [95% CI -1.8% to 0.1%]. Likewise, for every extra week that the child was exclusively breastfed, the likelihood of being obese declined by 0.66% [95% CI -1.4 to 0.06%]. While the magnitudes of effects were modest and marginally significant, the results were robust in a variety of specifications. CONCLUSION: The results suggest that hospital practices that support breastfeeding may influence childhood weight outcomes.

Maternal caffeine intake and intrauterine growth retardation.

This study estimates the effect of maternal caffeine consumption throughout pregnancy on fetal growth. We studied 2,714 women who delivered a liveborn infant between 1988 and 1991. Detailed information regarding coffee, tea, and soda drinking during the first and third trimesters of pregnancy was obtained. Average caffeine intake during month 1 of pregnancy was higher than for month 7 (72.4 vs 54.0 mg per day). Consumption of >300 mg caffeine per day during month 1 (adjusted odds ratio = 0.91; 95% confidence interval = 0.44--1.90) and during month 7 (adjusted odds ratio = 1.00; 95% confidence interval = 0.37--2.70) was not associated with intrauterine growth retardation. There was little evidence for any effect modification due to cigarette smoking on the caffeine associations. This study provides evidence that antenatal caffeine consumption has no adverse effect on fetal growth.

The effect of surfactant on birthweight-specific neonatal mortality rate, New York City.

PURPOSE: Surfactant has been shown to cause decreased neonatal mortality rate (NMR) in randomized studies of preterm infants. It is not clear whether the introduction of surfactant caused a decrease in neonatal mortality in a community. This study explores the hypothesis that the introduction of surfactant in 1990 to 1991 explains a decrease in neonatal mortality in New York City (NYC) among infants with birthweight of 500 to 1499 g. METHODS: For each of the 20 hospitals in New York City that began using surfactant in 1990 or 1991, we compared the NMR in the 2 years before the introduction of surfactant with the NMR in the 2 years after its introduction. Poisson regression models were fit to the death rates, adjusting for birthweight and other determinants of neonatal mortality. RESULTS: NMR in the 20 hospitals decreased by 13.7% (from 231.3 to 199.6 neonatal deaths per 1000 live births). This decrease remained significant after adjusting for birthweight and other risk factors. Infants with birthweight 1000 to 1249 grams benefited most from the introduction of surfactant; their NMR decreased by 19.6%. After adjusting for birthweight, those born before the introduction of surfactant were 1.18 times as likely to die in the first 27 days as those born after the introduction of surfactant (95% CI 1.04, 1.33). CONCLUSION: It appears that surfactant had a significant impact on NMR in NYC among very low birthweight babies.

A unique drug treatment program for pregnant and postpartum substance-using women in New York City: results of a pilot project, 1990-1995.

In the 1980s, there was virtually no drug treatment for pregnant women in New York City, especially women who used crack cocaine. The purpose of the Parent and Child Enrichment (PACE) demonstration project was to assess the effectiveness of the one-stop shopping model of drug treatment for this population. Among PACE clients, 88% were primarily users of crack cocaine. The mean total length of stay was 100.0 days (median 55.5 days). Client retention 42 days after intake was 54.3%. This paper describes the essential components of this program model. "Long-stay" and "short-stay" clients were compared using urine toxicology tests and activity logs. In addition, the birth outcomes of clients were compared to two similar populations. A strong positive correlation was found between total length of stay and low rate of positive urine drug tests (UDTs). Infants of PACE long-stay clients had greater mean birth weight, less low birth weight, and less intrauterine growth retardation than the infants of the comparison groups. Fetal exposure to cocaine was decreased dramatically among women who were enrolled for 42 or more days during their pregnancy. This model of drug treatment for pregnant and postpartum women seems to improve mothers' lives, fetal drug exposure, and birth outcome significantly.

Breast-feeding initiation in New York City, 1979 to 1996.

OBJECTIVES: The purpose of this study was to explore changes in breast-feeding initiation from 1979 to 1996 among infants born in New York City hospitals. METHODS: All New York City hospitals were surveyed every 2 years. Hospital staff reported feeding method at newborn discharge. RESULTS: New York City breast-feeding initiation rates increased consistently from 1979 to 1996 (from 29% to 58%, P < .0001), including 1984 to 1990, when rates decreased nationally. CONCLUSIONS: A 1984 New York State regulation requiring each hospital to designate a lactation coordinator may have been associated with the continuing increases in breast-feeding initiation.

Prediction of survival in gynecological cancer based on immunological tests.

Patients with advanced cancer have a depressed immunological function. We performed a battery of tests on peripheral blood samples from 42 patients with gynecological cancer to determine the extent to which this depression was due to abnormal lymphocyte function, as compared to changes in the number of lymphoid cells in the peripheral blood or in the efficiency of purification of cells in Ficoll:Hypaque gradients in preparation for testing. The percentage of lymphocytes in the gradient-derived cell suspension (% LG) and the absolute lymphocyte count were more informative than mitogen stimulation, mixed leukocyte culture, and T- and B-cell measurements. Both values decreased significantly with the advancing stage of cancer, and we were able to predict survival of patients with uniform stage of disease. The % LG correlated with survival better than did any other test when multivariate analyses of all test combinations were performed. Low values of % LG reflected both the depressed lymphocyte counts and the altered buoyant density of the leukocytes of many patients with advanced cancer. A large portion of the depression in other immune function tests was statistically attributed to changes in % LG and the lymphocyte counts. We concluded that these two simple measurements provide valuable information about patients with gynecological cancer.