While smoking during pregnancy increases the risk of health problems for developing babies, such as preterm birth, low birth rate and birth defects of the lip and mouth, could there also be an association to congenital diaphragmatic hernia (CDH), a rare musculoskeletal birth defect?
USF College of Public Health alumna Dr. Rema Ramakrishnan is investigating this possible association in a series of research papers focused on the role of maternal exposure to ambient cadmium as a risk factor for CDH in Florida and whether maternal smoking during pregnancy was an effect.
In July, Ramakrishnan had part two of her research from her dissertation published in the journal, Birth Defects Research.
The article, titled “Maternal Exposure to Ambient Cadmium Levels, Maternal Smoking during Pregnancy, and Congenital Diaphragmatic Hernia,” researched possible associations with exposure to ambient cadmium levels, such as cigarette smoke, during pregnancy and the development of congenital diaphragmatic hernia.
This birth defect occurs when the diaphragm muscle—the muscle that separates the chest from the abdomen—fails to close during prenatal development and the contents from the abdomen migrate into the chest through the hole.
“Though we did have enough evidence to detect an association between maternal exposure to ambient cadmium and CDH, I believe this may encourage researchers to delve into this topic more to unravel the role of other environmental exposures and gene-environment interactions,” she said.
According to Ramakrishnan, there is research into CDH but most of the research is clinical or surgical. Very few papers have been published about risk factors for this defect. The defect is extremely rare, about 2.6 per 10,000 live births, but with high mortality and morbidity. Infants that survive will need lifelong support and care.
“I have always been interested in adverse birth outcomes including prematurity, low birth weight, and birth defects,” she said. “I wanted to focus on a topic that has not been studied a lot, but was still important to be studied.”
Ramakrishnan’s first paper of three on this research, “Trends, Correlates, and Survival of Infants with Congenital Diaphragmatic Hernia and its Subtypes” was published last year. This current paper is her second and she plans to submit the part three shortly.
“I had read somewhere that very few people get their PhD projects published after they graduate,” she said. “I am happy that I was able to do so mostly with encouragement and support of my PhD committee members, Drs. Amy Stuart, Jason Salemi, Henian Chen, Kathleen O’Rourke and Russell Kirby, who are also co-authors on this paper.”
Currently, she does not have the opportunity to work with birth defects research but she plans to work on environmental and genetic risk factors for CDH and other birth defects in the future. She wants to research the impact of this defect on hospitalization costs and families.
As a postdoctoral student at the George Institute for Global Health, Nuffield Department of Women’s and Reproductive Health at the University of Oxford, Ramakrishnan works as an epidemiologist/biostatistician and a conjoint lecturer at the University of New South Wales in Sydney, Australia.
Her responsibilities primarily include working on the International Childhood Cardiovascular Cohort consortium and the UK Biobank study–analyzing data and writing papers for publication in high impact journals.
Her ultimate goal is to become a professor in epidemiology/biostatistics and to start a birth cohort to study exposures during pregnancy that impact short-term and long-term health of mothers and infants. She also hopes to research various methodological and statistics issues in epidemiologic research and focus on causal inference in epidemiology.
Ramakrishnan, R, Stuart, AL, Salemi, JL, Chen, H, O’Rourke, K, Kirby, RS. Maternal exposure to ambient cadmium levels, maternal smoking during pregnancy, and congenital diaphragmatic hernia. Birth Defects Research. 2019; 1– 9. https://doi.org/10.1002/bdr2.1555
Story by Caitlin Keough, USF College of Public Health