Publications

BACKGROUND: Potentially driven by the lack of mother-to-infant transmission of microbiota at birth, cesarean delivery has been associated with higher risk of offspring obesity. Yet, no studies have examined when delivery-mode differences in adiposity begin to emerge. In this study, we examine differences in infant weight and adiposity trajectories from birth to 12 months by delivery mode.

METHODS: From 2013 to 2015, we recruited pregnant women into the Nurture Study and followed up their 666 infants. We ascertained maternal delivery method and infant birth weight from medical records. We measured weight, length, and skinfold thicknesses (subscapular, triceps, abdominal) when infants were 3, 6, 9, and 12 months of age. The main outcome, infant weight-for-length z score, was derived based on the WHO Child Growth Standards. We used linear regression models to assess the difference at each time point and used linear mixed models to examine the growth rate for infant weight and adiposity trajectories. We controlled for maternal age, race, marital status, education level, household income, smoking status, maternal pre-pregnancy body mass index, and infant birth weight.

RESULTS: Of the 563 infants in our final sample, 179 (31.8%) were cesarean delivered. From birth to 12 months, the rate of increase in weight-for-length z score was 0.02/month (p = 0.03) greater for cesarean-delivered than vaginally-delivered infants. As a result of more rapid growth, cesarean-delivered infants had higher weight-for-length z score (0.26, 95% CI: 0.05, 0.47) and sum of subscapular and triceps (SS + TR) skinfold thickness (0.95 mm, 95% CI: 0.30, 1.60)-an indicator for overall adiposity-at 12 months, compared to vaginally-delivered infants.

CONCLUSIONS: Compared to vaginal delivery, cesarean delivery was associated with greater offspring rate of weight gain over the first year and differences in adiposity that appear as early as 3 months of age. Monitoring cesarean-delivered infants closely for excess weight gain may help guide primordial prevention of obesity later in life.

Background Preeclampsia is a leading contributor to maternal and perinatal morbidity and mortality. In mice experiments, manganese (Mn) and selenium (Se) are protective whereas cadmium (Cd) is promotive for preeclampsia. Epidemiologic findings on these chemical elements have been inconsistent. To confirm experimental findings in mice, we examined associations of trace minerals (Mn and Se) and heavy metals (Cd, lead [Pb], and mercury [Hg]) with preeclampsia in a birth cohort. Methods and Results A total of 1274 women from the Boston Birth Cohort (enrolled since 1998) had complete data on the exposures and outcome. We measured Mn, Se, Cd, Pb, and Hg from red blood cells collected within 24 to 72 hours after delivery. We ascertained preeclampsia diagnosis from medical records. We used Poisson regression with robust variance models to estimate prevalence ratios (PRs) and 95% CIs. A total of 115 (9.0%) women developed preeclampsia. We observed evidence of a dose-response trend for Mn (P for trend<0.001) and to some extent for Cd (P for trend=0.009) quintiles. After multivariable adjustment, a 1 SD increment in Mn was associated with 32% lower risk of developing preeclampsia (PR=0.68; 95% CI, 0.54-0.86), whereas a 1 SD increment in Cd was associated with 15% higher risk of preeclampsia (PR=1.15; 95% CI, 0.98-1.36). Null associations were observed for Se, Pb, and Hg. Conclusions Findings from our cohort, consistent with evidence from mice experiments and human studies, indicate that women with lower blood concentration of Mn or higher Cd are more likely to develop preeclampsia.

Exposure to ambient air pollution has been associated with greater risk of elevated blood pressure (BP) in adults and children. Recent evidence suggests that air pollution exposure in pregnancy may also portend increased risk for the next generation; however, few studies have examined this relationship. We conducted a prospective study of 1293 mothers in the Boston Birth Cohort (enrolled 1998-2012) and their children who had follow-up visits between 3 and 9 years of age and complete exposure and outcome data. Our primary exposure, ambient particulate matter ≤2.5 µm (PM2.5) concentration during pregnancy, was estimated by matching mother's residential address to the US Environmental Protection Agency's air quality monitors. We defined our primary outcome child systolic BP (SBP) percentile according to US reference (Fourth Report) and classified elevated BP as SBP ≥90th percentile. Our multivariable-adjusted cubic spline showed a sharp increase in offspring SBP percentile and risk for elevated BP when third-trimester PM2.5 concentration was ≥13 μg/m3 The highest versus lowest tertile of third-trimester PM2.5 exposure was associated with a 4.85 (95% confidence interval: 1.38-8.37) percentile increase in child SBP or a 1.61 (95% confidence interval: 1.13-2.30) times higher risk of child elevated BP. A 5-μg/m3 increment in PM2.5 during the third trimester was associated with a 3.49 (95% confidence interval: 0.71-6.26) percentile increase in child SBP or a 1.47 (95% confidence interval: 1.17-1.85) times higher risk of elevated BP. Our findings suggest that exposure to ambient PM2.5 during the third trimester of pregnancy is associated with elevated BP in children, ages 3 to 9 years.

Hepatitis E virus (HEV) is a major cause of acute viral hepatitis. Patients with chronic hepatitis B superinfected with HEV may progress to liver failure. Babao Dan (BD) is a traditional Chinese medicine widely used as an auxiliary option for the treatment of chronic hepatitis and liver cancer in China. This study aimed to evaluate the effect of BD on the management of HEV infection in a rabbit model. Sixty-two specific-pathogen-free (SPF) rabbits were divided randomly into five groups and treated with BD or placebo for 2 weeks. All rabbits were inoculated intravenously with rabbit HEV after initial administration. Then, rabbits were administered BD or ribavirin or placebo at 2 weeks post-inoculation (wpi) until faecal virus shedding showed negative. The duration of faecal virus shedding and levels of HEV RNA in faeces were reduced, and anti-HEV antibodies were detected in all rabbits in groups treated with BD before or after inoculation. Ribavirin treatment rapidly cleared HEV infection in SPF rabbits, but anti-HEV antibodies remained negative in 50 % of rabbits treated with ribavirin. These results indicate that ribavirin treatment was more effective in clearing HEV infection, while administration of BD before or after inoculation was effective in clearing HEV infection. Further clinical studies are warranted.