Gastroschisis, 2006–2015: Rising Slowly, and More Common Where Opioid Prescribing Is High

Gastroschisis is a serious birth defect of the abdominal wall: some of the baby's abdominal contents sit outside the body at birth. It needs surgery after birth and brings digestive and feeding problems in infancy that can affect development. It has been increasing worldwide, and an earlier study of 14 U.S. states found it rising from 1995 to 2012, fastest among mothers under 20.

Young maternal age is its strongest known link. Research also points to possible roles for smoking, genitourinary infections and prescription opioid use. This CDC analysis pooled data from 20 state surveillance programs, covering about 47% of U.S. births, to update the trends and to test the opioid link.

Key findings

• 2006–2010: 3,489 cases among 8,342,741 live births — 4.2 per 10,000.
• 2011–2015: 4,166 cases among 9,359,005 live births — 4.5 per 10,000, about 10% higher.
• By county opioid prescribing, 2006–2015:

The ratio moved around from year to year but stayed above 1.0 in every year studied.

By mother's age

Prevalence was highest by far for mothers under 20 every year — but it was the older groups that grew.

Cases per 10,000 live births.

• A steady linear increase over 2006–2015 appeared in three of the four age groups; the under-20 group, though highest, showed no significant linear rise.
• That differs from the 1995–2012 study, where the youngest mothers saw the biggest rise. This analysis covers more states and more recent years, but there is no clear explanation for the slowdown.
• In most age groups under 30, prevalence was higher for babies of non-Hispanic white and Hispanic mothers than of non-Hispanic black mothers — consistent with earlier U.S. and international reports.
• The opioid link was stronger among older mothers: comparing high with low prescribing, the prevalence ratio was 1.1 under 20, 1.2 at 20–24, and 1.6 at both 25–29 and 30 and over.

Gastroschisis prevalence by mother's age, 20 states, 2006–2015. Image from the Centers for Disease Control and Prevention

What the opioid finding means

Why gastroschisis is rising is not well understood. This analysis fits a large case-control study that linked self-reported prescription opioid use in the first trimester to gastroschisis, and another study where a combination of stressors, opioids among them, weighed more heavily on older mothers. No animal studies of the link have been published.

The two designs complement each other:

Together they make a strong case for finding out whether opioid exposure helps cause gastroschisis and its rise.

Prevalence ratio by county opioid prescribing, 20 states, 2006–2015. Image from the Centers for Disease Control and Prevention

How it was done

• Cases included every pregnancy outcome — live births, fetal deaths, terminations and other nonlive births — counted against live births in the same areas, using standard diagnosis codes.
• IQVIA Xponent, which estimates U.S. opioid prescriptions from a sample of about 59,000 pharmacies (88% of all prescriptions), gave CDC each county's prescribing category for every year; the state programs then counted cases and births in each category. No individual cases were reported to CDC by county.
• The high and very high (over 112.5) categories did not differ significantly, so they were combined as "high."

Limitations

1. An ecologic link cannot show cause: prescriptions could not be tied to individual mothers or to timing in pregnancy.
2. Prescription data for women only were not available, and they left out illicit opioids, buprenorphine for opioid use disorder and methadone from treatment programs — though women are more likely than men to be prescribed opioids and to get them by prescription.
3. Confounders were not accounted for: counties may differ in socioeconomic status, age at childbirth or overall age mix — an older population, for instance, may have more chronic pain and opioid use. Future work with patient-level data will look at these, and at illicit opioids, smoking and other substance use.

Why it matters

Since most babies with gastroschisis are born to mothers under 25, research into why young maternal age matters so much should continue. And a fuller picture of opioid use in pregnancy will give health care providers and women evidence-based information on the risks to a developing baby.

Sources

Based on "Gastroschisis Trends and Ecologic Link to Opioid Prescription Rates — United States, 2006–2015," by Tyiesha D. Short and colleagues, Morbidity and Mortality Weekly Report 68(2), Centers for Disease Control and Prevention; a work of the United States government in the public domain.