The use of opioids during pregnancy has become an issue in recent years, and researchers are now investigating whether the problem could be linked to the rise of a birth defect called gastroschisis.

The unborn human takes a developmental path so complex that with each twist and turn there's a chance of falling off the tracks, and drug use during pregnancy can often be a derailing force.

Gastroschisis (pronounced gas-troh-skee-sis) is a defect of the abdominal wall that occurrs early on in pregnancy and results in a baby's intestines spilling outside of their body through a hole in their belly.

While the condition does not have to be life-threatening, it does require immediate surgery with weeks of recovery, and can result in problems with eating and digestion that persist for many years after.

In most cases the cause of this defect is unknown, but the use of certain drugs and medications - including cigarette smoking, alcohol use, and aspirin use - has been identified as a significant risk factor.

New research from the US Centres for Disease Control and Infection (CDC) now points to another potential addition to that list: opioids. Analysing data from 20 different state surveys, researchers have noticed a worrying trend whilst analysing a sample of nearly half of all US births.

For every 10,000 live births between 2006 and 2010, the number of infants born with gastroschisis was roughly 4.2. But for some reason, over the following five years, this number rose to 4.5, representing a 10 percent increase in this defect from 2011 to 2015.

The findings are supported by several other studies, which have also found that this particular birth defect has recently and inexplicably become more common, especially amongst mothers younger than 20 years of age.

Unlike past analysis, however, this study found that babies born to mothers in their 20s and 30s were most affected by gastroschisis, a discrepancy that has yet to be properly explained.

But the most intriguing part of the study came when the researchers placed their findings alongside the annual rate of opioid prescriptions.

Across the entire decade, the prevalence of gastroschisis was more obvious among regions that handed out more opioid prescriptions.

In those US counties with a medium rate of opioid prescriptions, for instance, this horrible gut defect was found to be 1.4 times higher than the overall rate, reaching 4.6 per 10,000 live births. And in those counties with high prescription rates, the rate jumped all the way to 5.1 per 10,000 live births.

While the results are intriguing, that does not mean that opioids are causing gastroschisis. The study was only based on a birds-eye-view of the population, and it did not zoom in to link opioid prescriptions to individual mothers or examine the timing of opioid use during pregnancy.

Far from being conclusive, the findings act more as a compass, pointing future research on gastroschisis and opioid use in a compelling new direction.

"Having a better understanding of all possible effects of opioid use during pregnancy can help provide evidence-based information to health care providers and women about the potential risks to the developing fetus," the authors conclude.

This study has been published in the Morbidity and Mortality Weekly Report.