Neonatal Down syndrome diagnoses increase in US states with 20-week abortion bans

Key takeaways :

• Odds of neonatal Down syndrome were 22% higher after start of a 20-week abortion ban.
• Down syndrome is often not definitively diagnosed by 20 weeks’ gestation.
• Abortion bans at 20 weeks may thwart patient choice.

From 2011 to 2018, neonatal Down syndrome diagnoses increased more in states that banned abortion at 20 weeks’ gestation compared with states without such bans, according to a population-based cohort study published in JAMA Network Open.

“Twenty-week abortion bans affect individuals’ ability to have an abortion after second trimester testing, including for diagnoses of fetal chromosomal abnormalities such as trisomy 21 or Down syndrome,” Sarina R. Chaiken, BA, from the department of obstetrics and gynecology at Oregon Health and Science University, Portland, and colleagues wrote. “Although advances in earlier prenatal screening and genetic testing allow for screening prior to 20 weeks, many cases are often not definitively diagnosed until 20 weeks or beyond.”

This population-based, historical cohort study analyzed data from the National Vital Statistics System on 31,157,506 births (mean maternal age, 28.4 years) in the U.S. that occurred from 2011 to 2018. Researchers categorized states as those with or without 20-week abortion bans enacted during the study period and evaluated the adjusted odds of Down syndrome among births in these states after abortion bans were enacted.

A total of 15,951 neonates had a Down syndrome diagnoses at birth. The 20-week abortion bans were enacted among 17 U.S. states during the study period.

Among states with and without 20-week abortion bans, neonatal Down syndrome birth prevalence increased over time: from 48 to 58.4 per 100,000 births in the states with abortion bans and from 47.4 to 53.3 per 100,000 births in states without such bans.

After adjustment for state, birth year, maternal race and ethnicity, age,

educational level, insurance status and number of prenatal visits, odds of Down syndrome were higher in states after enaction of 20-week abortion bans compared with the years before the ban (adjusted OR = 1.22; 95% CI, 1.11-1.35). The researchers noted that with a baseline of 1 case of Down syndrome in 700 births, the number of cases would increase by 1,320 each year if abortion were banned at 20 weeks’ gestational nationwide.

“Terminating a pregnancy is a highly individual, personal decision between pregnant patients and their clinicians,” the researchers wrote. “Physicians and politicians should advocate against such bans to allow all pregnant individuals in the U.S. to make informed decisions, regardless of state of residence.”