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Published April 13, 2013, 11:30 PM

Technology to detect heartbeats has been around since 1972

FARGO – It might seem startling to learn that doctors can detect a fetal heartbeat as early as six weeks or slightly less. That capability has been highlighted in the ongoing debate about North Dakota’s new law banning abortions after detection of a fetal heartbeat. But fetal heart monitoring is nothing new to medicine; the methodology has been available through ultrasound since 1958.

By: Patrick Springer, INFORUM

FARGO – It might seem startling to learn that doctors can detect a fetal heartbeat as early as six weeks or slightly less.

That capability has been highlighted in the ongoing debate about North Dakota’s new law banning abortions after detection of a fetal heartbeat.

But fetal heart monitoring is nothing new to medicine; the methodology has been available through ultrasound since 1958.

Doctors’ ability to detect a heartbeat very early in pregnancy also dates back decades, predating the landmark Roe vs. Wade court decision in 1973 that made abortions legal throughout the United States.

Using more advanced ultrasound technology, a doctor in 1972 detected a heartbeat in a fetus at seven weeks of gestation, and the technology has been widespread for many years.

“This is not a new thing,” said Dr. Stephanie Dahl, a Sanford reproductive medicine specialist who also is certified as an obstetrician-gynecologist. “This has been around since 1972.”

Dahl, who was outspoken about abortion laws that she said threaten in vitro fertilization, her medical specialty, said she is neither pro- or anti-abortion, and works to help women become pregnant and have children.

Early fetal heartbeat monitoring has long been routine in high-risk pregnancies and among women who have difficulty with fertility.

Most pregnant women, however, do not receive ultrasound testing until the eighth or tenth week of gestation, said Dahl.

Also, those women who do not closely track their menstrual cycles might not quickly realize they missed their period and therefore not learn of their pregnancy until five or six weeks, Dahl said.

“A lot of women have no idea when they last ovulated,” she said.

By contrast, when dealing with women who are having difficulty becoming pregnant, or who are at risk for complications, fetal heart monitoring begins very early, and heartbeats can be detected as early as five weeks and five or six days, Dahl said.

When a woman learns she is pregnant at 4½ weeks, she would have days to decide whether to carry the child or seek an abortion, under North Dakota’s law banning abortions once a fetal heartbeat is detected.

“They literally have five or six days to make a decision,” Dahl said.

A bit confusingly, a woman isn’t actually considered pregnant in the first week or two; conception typically occurs about two weeks after a woman’s last period begins.

Therefore, to calculate the due date, a doctor counts ahead 40 weeks from the start of the mother’s last period. Fertilization, in which the sperm and egg unite, occurs in week three of fetal development.

The fertilized cells attach to the mother’s uterine wall during week four in a process called implantation, when the placenta begins to form.

At week five – that’s the third week after conception – the embryonic period begins, and the baby’s brain, spinal cord and heart start to form.

Then, at week six, a period of rapid growth, the baby’s heart begins to pump, and the body begins to assume a curved, C-shape, with buds that later develop into arms and legs.

At the 11th week of pregnancy – when first officially described as a fetus – the developing baby weighs almost a third of an ounce and measures about 2 inches from crown to rump, according to a Mayo Clinic description of fetal development.

Early pregnancy can be fraught with problems, and between 20 and 30 percent of pregnancies end in miscarriage, Dahl said.

Along with advances in fetal monitoring, medicine has made great strides in keeping premature babies alive in neonatal intensive care units, or NICUs.

That means fetal viability can begin earlier than what was thought in 1973, now at around 22 to 24 weeks, Dahl said. The Supreme Court’s Roe v. Wade decision allows abortions until a fetus becomes viable, or able to live outside the mother’s womb.

A baby born at 24 weeks of gestation has a mortality risk of 50 percent, according to figures from the Sanford NICU. Premature babies usually stay in the NICU until the equivalent of 37 or 38 weeks, although the period varies.

Of those “preemies” who survive, roughly half are at risk for long-term neurodevelopmental complications, including blindness, deafness or cerebral palsy.

To try to prevent those outcomes, during pregnancy and labor, doctors use sophisticated monitoring equipment, including ultrasound, to track health and identify problems.

Use of fetal electronic monitoring during labor has grown dramatically over the past three decades. A device records fetal heartbeat and uterine contractions, a common obstetrical procedure called cardiotography.

In 1980, fetal electronic monitoring was used in about 45 percent of pregnancies. That rate increased to 85 percent by 2002, according to the American College of Obstetricians and Gynecologists.


Readers can reach Forum reporter Patrick Springer at (701) 241-5522

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