Measuring the Prevalence of Neural Tube Defects: Why Global Surveillance Needs Improvement Now

Birth Defects Insights, a Teratology Society Blog

By Vijaya Kancherla, MS, PhD

“My name is Amanda Mateus. I am the mother of three sons and one daughter. My youngest son has Spina Bifida.” Amanda is not alone. In fact, she’s joined by countless families around the world dealing with the after-effects of neural tube defects (NTD), like spina bifida and anencephaly, which are largely preventable. “I believe that advocating for better birth defect prevention research is not devaluing in any way those who have a birth defect,” writes Mateus. “If it weren’t for research, knowledge, and implementations, many people who now live with a birth defect would not be alive today.” It’s the core reason behind the Teratology Society’s passion to reduce birth defects worldwide and it’s what drove the latest publication of a position statement on the surveillance and methods for prevalence estimation of NTDs in a recent issue of the Birth Defects Research journal. Considering that the most prestigious society in this field has only published official positions on a handful of other birth defects-related issues, this is significant. Here’s why it’s chosen to focus on the critical issue of NTDs.

NTDs are some of the most common types of birth defects occurring worldwide.

NTDs occur when the neural tube, which forms the brain and spinal cord in the fetus, is not closed completely. NTDs form around the 4th week of gestation, when most women are unaware of their pregnancies. There are different kinds of NTDs depending on the level where the neural tube closure fails. They can be easily identified during pregnancy and at birth. Anencephaly, spina bifida and encephalocele are common forms of NTDs. Babies born with spina bifida face a high risk of death in early childhood and suffer lifelong disability and health issues. Babies with anencephaly die soon after birth. In addition, many anencephaly and spina bifida‐affected pregnancies result in stillbirths or are electively terminated after prenatal diagnosis, depending on availability of prenatal diagnostic services and existing elective termination policies.

Anencephaly and spina bifida affect pregnancies worldwide and are largely preventable when the mother takes folic acid before and during early pregnancy.

Birth defects tracking or surveillance systems measure the occurrence of NTDs in the society. A good surveillance system is designed to track all pregnancy outcomes. Miscarriages, elective terminations after a prenatal diagnosis of NTD, and stillbirths that are associated with NTD have to be counted to understand the total number of NTDs occurring in the population. Such systems give us a complete picture of NTDs. But many countries only count NTDs among babies that are born alive, which is like looking at the tip of an iceberg. Good birth defects surveillance systems that count all pregnancies rarely exist in developing countries, where NTDs are expected to affect a high number of pregnancies because mothers lack enough folic acid in their diets for a healthy pregnancy. There are many NTD cases that are missed by not counting all affected pregnancies, and are therefore invisible. Incomplete surveillance has severe consequences, as it thwarts prevention efforts.

The subject of the Teratology Society position statement was conceived by Dr. Robert J. Berry (Emory University), as public health action for NTD prevention has been long hindered by a lack of, or inaccuracies in, existing surveillance in many countries where the prevalence of NTD-affected pregnancies is often especially high. In December 2016, Drs. Berry and Vijaya Kancherla (Emory University) were involved in the Technical Consultation on Folate Status in Women and Neural Tube Defect Prevention, and contributed to several publications on current knowledge, gaps, and challenges in the occurrence of spina bifida and anencephaly globally. Their contribution was integrated into a series of publications in the New York Academy of Sciences in 2018.

During the 57th Annual Meeting of the Teratology Society in Denver in 2017, a symposium focused on informing the meeting participants about the continuing issue of incomplete surveillance and prevalence estimation procedures for the global burden of congenital disorders. At the end of the symposium one of the audience members asked what the Society could do to address the issue. That question became the seed for the position statement. Drs. Vijaya Kancherla and Robert Berry joined with two other interested birth defects surveillance and epidemiology experts, Suzan Carmichael (Stanford University) and Marcia Feldkamp (University of Utah) and drafted the position statement to promote better surveillance of NTD globally. The position statement was endorsed by the Society in 2018.

The statement’s nuts and bolts for building a better surveillance system.

In the position statement, the Teratology Society acknowledges the value of accurate measurement of all cases of NTDs in a population, including all pregnancy outcomes, not just live births. The need for comprehensive surveillance is presented as an essential investment for accelerating the prevention of NTDs. The issue raised is that governments in low and middle income countries where there are a high number of NTD cases that result in stillbirths, and in countries where NTDs are electively terminated soon after prenatal diagnosis, rarely can provide a complete assessment of burden of these birth defects. The impact of NTD-related pregnancy losses among families and societies cannot be ignored! In the position paper, the Society addresses this issue, and recommends approaches for standardizing and improving NTD prevalence estimation that allow capturing all cases and estimating total prevalence. The statement also promotes population-based surveillance methods that utilize multiple data sources and standard data collection protocols to study all pregnancies, as well as neonatal mortality associated with NTDs. The statement promotes assessment of all NTD phenotypes (i.e., anencephaly, spina bifida, encephalocele, and other types of NTDs) and those co-occurring with other major birth defects, or as part of a syndrome, to understand their total prevalence.

A global call for help.

The Teratology Society calls for a collective effort by countries to engage in robust surveillance of NTDs globally by following standard procedures. Partner organizations that have endorsed the statement include the Organization of Teratology Information Specialists (OTIS)/MotherToBaby, Developmental Neurotoxicology Society (DNTS), European Teratology Society (ETS), the National Birth Defects Prevention Network (NBDPN), and the Board and Scientific Committee of the European Network of Teratology Information Services (ENTIS).

The Mateus Family

“I can’t pretend that we don’t struggle sometimes.”

Amanda hopes others join the global call as she explains the challenges her family faces with her son’s spina bifida. “The physical, emotional, and even financial burdens can be overwhelming at times. We understand that everyone faces challenges, but we want to recognize that there can be unique challenges affecting people with disabilities and their families. We share our story with the hopes that someone will find comfort, will know that they are not alone, and to encourage research that will continue to improve the lives of everyone.”

Together, during January Birth Defects Prevention Month and every month, we can prevent birth defects like NTDs. So who else is ready to join the movement and do what’s #Best4YouBest4Baby?

About the Author

Vijaya Kancherla, MS, PhD, completed her PhD in epidemiology at the University of Iowa and then went on to the Pierre Decouflé Post-Doctoral Fellowship at the CDC National Center on Birth Defects and Developmental Disabilities. Currently Dr. Kancherla is a Research Assistant Professor at the Rollins School of Public Health at Emory University. Dr. Kancherla was introduced to the study of birth defects early in her doctoral program and instantly recognized the need and impact of this field.

About the Teratology Society

To understand and prevent birth defects and disorders of developmental and reproductive origin, the Teratology Society promotes multi-disciplinary research and exchange of ideas; communicates information to health professionals, decision-makers, and the public; and provides education and training. Scientists interested in or already involved in research related to topics mentioned in this blog are encouraged to join the Teratology Society and attend the 59th Annual Meeting June 22–26, 2019, the premier source for cutting-edge research and authoritative information related to birth defects and developmentally-mediated disorders. Teratology Society members include those specializing in cell and molecular biology, developmental biology and toxicology, reproduction and endocrinology, epidemiology, nutritional biochemistry, and genetics, as well as the clinical disciplines of prenatal medicine, pediatrics, obstetrics, neonatology, medical genetics, and teratogen risk counseling. In addition, the Teratology Society publishes the scientific journal, Birth Defects Research. Learn more at Find the Teratology Society on LinkedIn, Facebook, and Twitter.