Now that several states have passed bills that effectively ban abortion after a fetal heartbeat can be detected, the new laws are raising a lot of questions about early pregnancy and miscarriage treatments.
The fetal heartbeat can typically be seen on an ultrasound at around six weeks into pregnancy, but many women have no idea they’re pregnant at that time. So when do women typically realize that they are pregnant? And how often are pregnancies unplanned? We’ll explain all of this and more.
How is the length of pregnancy measured?
It sounds odd, but doctors measure the beginning of a pregnancy as being the first day of your last period. Why? They’re tracking the length of pregnancy using a nearly 200-year-old calculation called Naegele’s Rule, named after Franz Karl Naegele, the German obstetrician who is credited with creating it in the 1800s.
Here’s how it works: To figure out when a woman will give birth, doctors start with the first day of the woman’s last menstrual period, count back three calendar months and then add one year and seven days to that date.
The rule is somewhat confusing, because conception usually doesn’t occur until around 14 days after the first day of your period, assuming you have a 28-day cycle (which many women do not for a variety of reasons). The reason doctors still use the last menstrual cycle as a benchmark is because it is difficult to know exactly when the sperm fertilized the egg.
So when doctors say a woman is six weeks pregnant, it typically means the embryo started developing about four weeks ago.
The heart, which can be seen flickering on an ultrasound, is still maturing and cannot be heard until several weeks later.
Perhaps this is the simplest way to say it: Six weeks pregnant is two weeks after a woman misses her period.
What does the latest abortion legislation mean for women with unviable pregnancies?
Georgia, Kentucky, Mississippi and Ohio have this year passed so-called heartbeat bills, which effectively prohibit abortion after six weeks, and other states are poised to follow in their footsteps.
According to the American College of Obstetricians and Gynecologists, one of the biggest concerns of their members right now is about how to interpret the scope and application of these laws in their practice. In some instances, that extends beyond the delivery of abortion care to questions about miscarriage treatments like dilation and curettage, which removes tissue from inside of the uterus.
For now, abortion is still legal because these laws have not yet taken effect. In addition, the legislation is expected to be challenged in court because of the precedent set by the 1973 Roe v. Wade Supreme Court decision, which says abortion is legal until the fetus reaches viability, usually at 24 weeks.
When do women first learn that they are pregnant?
While there isn’t clear data as to when women typically find out that they are pregnant, Dr. Dana R. Gossett, the vice chair of obstetrics and gynecology at the University of California, San Francisco, said that in her practice she often sees women who don’t realize they are pregnant until after the six-week mark.
“Typically, clinical symptoms like fatigue and nausea don’t start until after six weeks,” Dr. Gossett said, though there are some women who are more sensitive to early pregnancy symptoms.
What’s more, women with irregular menstrual cycles might find it “especially challenging” to discover that they’re pregnant right away, Dr. Gossett said. “What are they supposed to do? Check pregnancy tests every four or five weeks?”
Dr. Sarah Horvath, a family planning fellow at the American College of Obstetricians and Gynecologists, agreed.
“Unless a woman is actively trying to get pregnant, she is unlikely to know that she is pregnant at six weeks,” she said.
Nikki Young, 42, who lives in Riverview, Fla., said she and her husband were surprised to discover eight years ago that she was pregnant.
“It was mixed feelings,” she said.
At the time, their second child was only about 1-year-old and she wasn’t actively monitoring her period.
“I didn’t really keep track of it that closely,” she recalled. But then, one day she noticed she was spotting and realized she had missed her period entirely. A home pregnancy test and a visit to the doctor confirmed that her third child was on the way.
How many women have unplanned pregnancies?
Nearly half of pregnancies in the United States are unplanned.
A 2016 study published in the New England Journal of Medicine examined the rate of unintended pregnancy in the United States from 2008 to 2011 and found that 45 percent of pregnancies in 2011 were not planned. That’s 2.8 million unintended pregnancies, of which more than 40 percent would end in an abortion.
While the rate of unintended pregnancies declined from 2008 to 2011, the number of women who sought abortions for their unintended pregnancies changed very little. And in 2011, just like in 2008, unintended pregnancy remained most common among women and girls who were poor and those who were cohabiting.
“Lower-income women, rural women and women with limited access to health care will be disproportionately affected by these laws,” Dr. Horvath said. “Women of means will be able to travel to other states, or other countries, just as they did before Roe v. Wade.”