Like most aspects of biology, early human development involves many complex processes. Despite the rhetoric around these issues, clear lines — between having a heart and not having a heart or being able to survive outside of the uterus — are scarce, or nonexistent.
“There aren’t these set black-and-white points for much of this,” says obstetrician-gynecologist Nisha Verma, a fellow with the American College of Obstetricians and Gynecologists in Washington, D.C.
Here’s what’s known about five key aspects of pregnancy biology that often come up in abortion debates.
1. The early timeline of a pregnancy is easy to misunderstand.
That’s because how dates are determined is supremely confusing. The standard pregnancy clock actually starts ticking before a sperm cell encounters an egg, two weeks before, on average.
3. “Heartbeat laws” are not what they seem.
A Texas law bans abortions “after detection of an unborn child’s heartbeat.” But the rhythmic sounds heard on an ultrasound early in pregnancy aren’t caused by the opening and closing of heart valves as they move blood through the heart’s chambers, the motion that produces a typical lub dub sound. That’s because those chambers haven’t yet developed. On early ultrasounds, the heartbeat-like sounds are created by the ultrasound machine itself.
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5. When a fetus could survive on its own is a complex medical calculation.
The word “viability” is often used as a sharp cut-off point to mark the age at which a fetus could survive outside of the uterus. The problem is that one clear cut-off does not exist.
