Critical windows of susceptibility for the effects of prenatal exposure to heat and heat variability on gestational growth.

Background: Studies have shown that prenatal heat exposure may impact fetal growth, but few studies have examined the critical windows of susceptibility. As extreme heat events and within season temperature variability is expected to increase in frequency, it is important to understand how this may impact gestational growth.

Objectives: We investigated associations between various measures of weekly prenatal heat exposure (mean and standard deviation (SD) of temperature and heat index (HI), derived using temperature in °C and dew point) and term birthweight or odds of being born small for gestational age (SGA) to identify critical windows of susceptibility.

Postnatal exposure to PM and weight trajectories in early childhood.

Background: Inconsistent evidence has assessed the impact of air pollution exposure on children's growth trajectories. We investigated the role of 90-day average postnatal fine particulate matter (PM) exposures by estimating the magnitude of effects at different ages, and the change in child weight trajectory by categories of exposure.

Methods: We obtained weight values from electronic health records at each hospital visit (males = 1859, females = 1601) from birth to 6 years old children recruited into the Boston-based Children's HealthWatch cohort (2009-2014).