Neonatal Down syndrome increased more in states that enacted 20-week abortion bans: JAMA

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. 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. In these cases, patients in states with 20-week abortion bans may have insufficient time to make an informed decision and may be denied desired abortion care. Down syndrome is the most common chromosomal disorder, affecting approximately 1 in every 700 births.

There remains a paucity of literature regarding how the increase in 20-week abortion bans were associated with rates of neonatal Down syndrome. Evaluating the association of these bans with the rate of fetuses with Down syndrome carried to viability is necessary to optimize health planning and better estimate the burden on people facing further restrictions to abortion care, given recent legislature. Therefore, a study aimed to examine the association between rates of Down syndrome diagnosed in states with and states without 20-week abortion bans in the US from 2011 to 2018 to better understand how such bans were associated with outcomes in pregnancies with Down syndrome.

This population-based, historical cohort study used National Vital Statistics System data on 31,157,506 births in the US from 2011 to 2018. Statistical analysis was performed from May 2021 to February 2023. States were categorized as those with or without a 20-week abortion ban enacted during the study period. Multivariable logistic regression evaluated the adjusted odds of Down syndrome among births in states that enacted 20-week abortion bans after the abortion ban enactment, adjusting for state, year of birth, maternal race and ethnicity, age, educational level, insurance, and number of prenatal visits.

The cohort consisted of 31,157,506 births (mean [SD] maternal age, 28.4 [5.9] years) in the United States, of whom 15 951 neonates (0.05%) received a diagnosis of Down syndrome at birth.

A total of 17 states enacted 20-week abortion bans during the study period, and 33 states did not enact bans.

In both states with and states without bans, the birth prevalence of neonatal Down syndrome increased over time; in states with bans, rates increased from 48.0 to 58.4 per 100 000 births; in states without bans, rates increased from 47.4 to 53.3 per 100 000 births.

In multivariable logistic regression assessing the interaction of time and presence of a 20-week abortion ban, the odds of Down syndrome were higher in states that enacted 20-week abortion bans after enactment of the law compared with the years prior to enactment of the ban (adjusted odds ratio, 1.22; 95% CI, 1.11-1.35).

In this study, authors demonstrated that, in the US between 2011 and 2018, the odds of a neonatal Down syndrome diagnosis were higher in states that enacted 20-week abortion bans in this period compared with states that did not enact such bans. Although states with and states without bans had statistically insignificant differences in neonates who received a diagnosis of Down syndrome in 2011, by 2018 there were more diagnoses in states with 20-week abortion bans. Although demographic and individual characteristics differed between states with and states without 20-week bans, when adjusting for cofounders as well as state, year of ban enactment, and year of birth, deliveries in states with bans were more likely to be associated with a neonatal diagnosis of Down syndrome than those in states without bans. From our multivariable analysis, study found that births in states that enacted 20-week abortion bans were 1.22 times as likely to have a diagnosis of Down syndrome as those in states without 20-week bans.

This cohort study found that among births in states where 20-week abortion bans were enacted, there were increased odds of neonatal diagnosis of Down syndrome compared with states without bans. These results suggest that 20-week abortion bans may inhibit choice in decision-making in the context of second-trimester aneuploidy screening. Terminating a pregnancy is a highly individual, personal decision between pregnant patients and their clinicians. Physicians and politicians should advocate against such bans to allow all pregnant individuals in the US to make informed decisions, regardless of state of residence.

Source: Sarina R. Chaiken, Ava D. Mandelbaum, Bharti Garg; JAMA Network Open. 2023;6(3):e233684. doi:10.1001/jamanetworkopen.2023.3684