"Before Monday, abortions were allowed through the 20th week of pregnancy in Iowa.
Iowa now joins a growing list of Midwestern states, including its neighbouring Missouri and South Dakota, that have enacted restrictions since Roe's overturn.
The ban is expected to force state residents to seek care in adjacent Democrat-led states that have taken action to maintain or expand abortion access since 2022, building pressure on providers in Illinois and Minnesota.
"As our neighbors in Iowa are stripped of their fundamental rights, my message is clear: Your reproductive freedom will remain protected in Minnesota," Governor Tim Walz posted on X, formerly Twitter.
Illinois Governor JB Pritzker called the six-week abortion ban "disturbing".
"Here in Illinois, we will welcome our Iowan neighbors for reproductive freedom and whatever care they need," he wrote on X.
Iowa Republicans had passed their prohibition last summer after failing in an identical effort six years ago.
The legislation hinges on what lawmakers deemed a "detectable foetal heartbeat" - a term medical groups say mischaracterizes the electronic impulses that signify early cardiac development.
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But polls show that nearly two-thirds of Iowans believe abortion should be legal in most or all cases."
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Big Gov Republicans know what's better for women in Iowa than 2/3rds of Iowans do?