Extreme heat exposure in pregnancy and risk for preterm birth, low birth weight and stillbirths

Background

Exposure to high ambient temperatures during pregnancy may increase the risk of adverse pregnancy outcomes due to physiological and anatomical changes in pregnancy compromising the ability to thermoregulate.

Methods

A systematic review and meta-analysis of studies that assessed associations between ambient heat, and preterm birth, birth weight and stillbirths. Articles were identified through a search of Medline (PubMed) and Web of Science. Titles and abstracts were screened, eligible studies extracted and risk of bias assessed using the Joanna Briggs Institute appraisal tools.

Results

14,880 records were screened and a total of 70 studies included. In 40 of 47 studies, preterm births were more frequent at higher than lower temperatures. In random effects meta-analysis, the odds of a preterm birth rose 1.05-fold per 1 °C increase in temperature (95%CI=1.03, 1.07), and 1.16 fold during heat waves (95%CI=1.10, 1.23). Reduced birth weight associated with higher temperature was found in in 18 of 28 studies, with considerable heterogeneity. Studies on stillbirths (n = 8) all showed temperature-stillbirth associations, with stillbirths increasing 1.05-fold per 1 °C rise in temperature (95%CI=1.01, 1.08). Associations between temperature and outcomes were largest among women in lower socioeconomic groups and at age extremes. The multiple temperature metrics and lag analyses limited comparison between studies and settings.

Conclusions

As frequency of heat exposures is increasing, prevention for pregnant women during heat waves should become a standard aspect of heat adaptation.

Key messages

Increase in extreme temperature events may have major implications for child health unless much more is done to provide heat adaptation services for pregnant women. Links between socio-economic status and study outcomes suggest higher vulnerability for already disadvantaged groups.

Methylation profiles of 22 candidate genes in breast cancer using high-throughput MALDI-TOF mass array

Alterations of DNA methylation patterns have been suggested as biomarkers for diagnostics and therapy of cancers. Every novel discovery in the epigenetic landscape and every development of an improved approach for accurate analysis of the events may offer new opportunity for the management of patients. Using a novel high-throughput mass spectrometry on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) silico-chips, we determined semiquantitative methylation changes of 22 candidate genes in breast cancer tissues. For the first time we analysed the methylation status of a total of 42 528 CpG dinucleotides on 22 genes in 96 different paraffin-embedded tissues (48 breast cancerous tissues and 48 paired normal tissues). A two-way hierarchical cluster analysis was used to classify methylation profiles. In this study, 10 hypermethylated genes (APC, BIN1, BMP6, BRCA1, CST6, ESRb, GSTP1, P16, P21 and TIMP3) were identified to distinguish between cancerous and normal tissues according to the extent of methylation. Individual assessment of the methylation status for each CpG dinucleotide indicated that cytosine hypermethylation in the cancerous tissue samples was mostly located near the consensus sequences of the transcription factor binding sites. These hypermethylated genes may serve as biomarkers for clinical molecular diagnosis and targeted treatments of patients with breast cancer.