3 key facts about fetal viability and its pivotal role in US abortion laws

• Fetal viability refers to how soon a fetus can be born and survive outside of its mother's womb.
• Fetal viability is typically set at 23 weeks of gestation but varies depending on certain factors.
• Currently, 18 states have tried to ban abortion before viability including Mississippi and Texas.

More than 23% of American women will have an abortion by the time they're 45, making abortion a common medical procedure. Abortion is also a hotly-contested political, ideological, and legal issue.

One of the most common discussions in the abortion debate is about fetal viability, the point at which a fetus can survive outside the womb.

Fetal viability is both a medical concept and a legal one, but the time frame for fetal viability is not a concrete one, says Nisha Verma, MD, Darney-Landy Fellow at American College of Obstetrics and Gynecologists (ACOG) and a complex family planning specialist.

"There is no specific benchmark. Fetal development during pregnancy is a gradual, fluid process and each pregnancy is different," she says.

Despite that, the idea of fetal viability is at the cornerstone of US abortion law. The Supreme Court is currently considering a case from Mississippi, Dobbs v. Jackson, which could allow states to ban abortion well before viability and reduce abortion access nationally.

Here are three key facts about fetal viability to help you understand the debate and the laws around abortion.

1. Fetal viability is a fetus's ability to survive outside the womb

Viability is the point at which a fetus could survive outside the uterus if provided medical care, says Stephanie Culver, MD, an OB-GYN with Pandia Health, an online birth control delivery service.

The concept of fetal viability has been used widely since 1973, when Roe v. Wade ruled that states could regulate or ban abortion after a fetus becomes viable. In practice, that means it is very difficult to get an abortion after 24 weeks gestation.

Legally speaking, Roe protects a woman's right to abortion up until the point of viability. The US Supreme Court is currently considering Dobbs v. Jackson, which deals with a Mississippi law that would ban abortion after 15 weeks of pregnancy. This is well before fetal viability and therefore directly in opposition to Roe v. Wade.

The Supreme Court has already heard arguments in the Mississippi case and a ruling is expected in 2022.

2. Fetal viability starts at around 23 weeks

The exact point that a fetus becomes viable has been debated for decades.

The ACOG — a leading medical authority on women's health and reproductive medicine — provides a range between 20 and 25 weeks of gestation calling this period "periviable." During this window there is a high likelihood of death and near certainty of disability for the infant, says Verma.

Variables including the fetus's size, sex, and access to medical care can impact chances of survival. Delivery this early also has additional complications for the birth parent, including increased likelihood of a cesarean delivery and increased risk for uterine rupture with future pregnancies.

It is possible for babies delivered at 23 weeks (about 5 months) gestation to live, but only about 5% will survive and practically all of those surviving infants will have morbidity, or medical complications other than death such as cerebral palsy and brain damage.

"Delivery before 23 weeks of gestation typically results in neonatal death," says Culver.

By 26 weeks, most premature infants will survive, but even these babies have increased risk for developmental and intellectual disabilities.

3. 18 states have tried to ban abortion before viability

Eighteen states have passed laws to ban abortion before fetal viability. In 17 out of the 18 states, abortion is legal up to 22 weeks of gestation.

Many of these bans have been struck down or not yet enacted because they are in violation of federal law as it currently stands. However, two pre-viability bans are functionally in effect:

• Mississippi's single abortion clinic only provides abortion up to 16 weeks.
• Texas law bans abortion after 6 weeks of gestation, or two weeks after a person misses their period.

If the Supreme Court overturns Roe v. Wade, which could happen with the Dobbs v. Jackson ruling, 26 states are expected to ban abortion before viability. This could put pregnant people's lives in danger, says Verma, since pregnant people are 14 times more likely to die from childbirth than from abortion.

"I have cared for people that have needed life-saving abortions for many different reasons," she says. She has provided abortions to a cancer patient who needed an abortion at 14 weeks in order to get life-saving chemotherapy; a patient who developed a uterine infection at 17 weeks that would have killed her if not for an abortion; and a mother of twins with a life-threatening heart condition made worse by pregnancy, who conceived while on birth control.

"Abortion is much safer than continuing a pregnancy to delivery, and in some cases, the difference may be life and death," says Verma.

Insider's takeaway

Despite the debate over viability, more than 98% of abortions occur before 21 weeks, before viability. Most abortions after 21 weeks happen when the parent or fetus has a life-threatening condition. The ACOG supports abortion access without restrictions as part of overall healthcare.

"Pregnancy and childbirth come with significant risks to a person's health, and for many women these are some of the most dangerous things they will do in their lives," Verma says. "Every person deserves the ability to make important decisions about their lives, health, and pregnancies."