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Causes of 80 percent of birth defects are unknown, U. study says

Birth data over a five year period in Utah suggests that the root cause of nearly 80 percent of all serious birth defects cannot be identified, according to a University of Utah Health study published this week in the British Medical Journal.
Birth data over a five year period in Utah suggests that the root cause of nearly 80 percent of all serious birth defects cannot be identified, according to a University of Utah Health study published this week in the British Medical Journal.
British Medical Journal Publishing Group

SALT LAKE CITY — Given just a moment to think about it, Amanda Mateus can list off how old her son Zac was when he endured major surgeries or hospital stays.

Ten months after Zac was born. At 4 years old. At 5 years. And again this January, Zac, who turned 9 on Friday, was back in the hospital with an infection in his knee.

The Spanish Fork boy suffers from spina bifida, a birth defect that keeps him in a wheelchair and is likely to necessitate further major procedures on his legs in the future.

"Birth defects affect every aspect of someone's life," Mateus said. "It affects the entire family in so many different ways emotionally, financially."

But despite the defect that has deeply affected their lives, the Mateus family is still in the dark as to what ultimately caused it.

"It could be a variety of things," Mateus said. "We don't know."

Mateus is not alone. Birth data over a five-year period in Utah suggests that the root cause of nearly 80 percent of all serious birth defects cannot be identified, according to a University of Utah Health study published this week in the British Medical Journal.

That figure indicates much more research needs to be done so women who plan on having a baby can utilize additional preventative measures before and during pregnancy, the study concluded.

In other words, the next folic acid — a vitamin that beginning in the 1990s was heralded as profoundly effective in preventing some birth defects — could very well exist, currently undetected because of a lack of scientific discovery. That's according to the study's lead scientist, Marcia Feldkamp, an associate professor in the U.'s Division of Medical Genetics in the Department of Pediatrics.

"We've got to find other 'folic acids,'" Feldkamp said. "I'm sure they're there. It's just going to take us a while."

Nearly 271,000 state birth records between 2005 and 2009 listed in the Utah Department of Health's public health surveillance system were used for the study. That database yielded more than 5,500 cases of children born with birth defects. Of those cases, a "definite cause" can be identified in just 20.2 percent of births, the study finds.

"These findings underscore the gaps in our knowledge. … For the causes that are unknown, better strategies are needed," the study concludes.

The conclusion stated such strategies include better coordination between different niche researchers, improved communication between researchers and clinicians, and a more sophisticated way to measure fetal exposure to certain substances that is independent of the self-reporting of the mother.

Feldkamp said the findings are complicated by the fact that, for some believed causes of birth defects, such as the mother smoking, there is not currently a way to definitively identify those factors as the cause in any one individual case. For other causes, such as gestational diabetes, several complex indicators must be met in order to identify that condition as the birth defect's direct cause, she added.

Feldkamp said, however, that it's likely that those cases make up "probably a pretty small percent" of the roughly 80 percent of birth defects whose cause was unknown. The study doesn't provide for an exact estimate of that percentage, she said.

Major birth defects occur in 1 in 33 births across the world, the U. said in a statement announcing the study's findings. About 1 in 5 deaths for children under a year old in the United States are associated with birth defects, according to data collected in 2013.

A lack of knowledge about what causes some birth defects does more than stagnate prevention efforts, according to Feldkamp. Such a situation could even escalate the risk for some defects in the future, she said, "if there's new environment (or) exposures introduced to the general public … a new medicine, for example."

"There's a possibility for an increase" in some defects, she said.

Feldkamp said one important takeaway of the study is that, for all the advancements in prenatal care, there is no room for complacency in the field.

"We've got a lot of work to do, a lot of research to figure out what may be causing these ... and what factors may be out there that may (affect) a woman's risk," Feldkamp said.

The study's conclusion echoed that sentiment, stating that "understanding the (cause) of birth defects should be both a public health and research priority."

Of the slightly more than 20 percent of defect cases with a known cause, 94.4 percent of those were attributed to chromosomal or genetic conditions, 4.1 percent were attributed to environmental exposure and 1.4 percent were attributed to twin-specific conditions.

The study, published Tuesday, was a five-year project that was finalized in December, according to Feldkamp.

Mateus doesn't keep herself up at night wondering what precisely caused her son's spina bifida, something she believes is a fruitless exercise for her.

"For me, I think if I allow myself to dwell on that, it would be (demoralizing)," she said. "I can't (do that). I just have to dwell on the here and now."

But Mateus also knows parents she has encountered online who can't stop blaming themselves for whatever their child is suffering through. That's partly because they still don't know why the birth defect happened, and whether they could have prevented it, she said.

"They feel like it was their fault," Mateus said. "There's a lot of lack of understanding and education."

Mateus looks forward to the day when parents and prospective parents are simply armed with more information.

"It does not devalue those who already have birth defects," she said. "It's the fact that we believe in improving and in reducing the pain that can come along with some of these issues. We want to advocate for a better future for those (children) that come (later)."