The Medical (and Political) Problem with 20-Week Abortion Bans

By Rachel Walden |

Protest rally in Austin against anti-abortion legislation / Photo by

The recent wave of anti-abortion legislation has caused much confusion and concern over what the future of reproductive healthcare might look like in a few years. Texas recently enacted a 20-week abortion ban, and 13 states have passed similar bans. In Congress, Republican senators are pushing to bring a 20-week abortion ban up for a vote after the August recess, reports .

Let’s first look at the language in these bills, which usually reference “20 weeks post-fertilization.” Aside from the restrictive issues, these post-fertilization bans present a major problem — that’s not how pregnancy is measured. When a doctor or midwife indicates that someone is “20 weeks pregnant,” what they mean is that it has been 20 weeks since the first day of the last menstrual period (or LMP).

This can be a bit confusing, because the first day of the last period is not when ovulation followed by fertilization actually occur. This LMP method is used because it’s the easiest to measure. While ovulation is often estimated at about two weeks after the start of the last menstrual period, it can occur at different times for different people, making it impossible to know exactly when ovulation — or fertilization or implantation, for that matter — occurred.

LMP, however, is something we can point to on a calendar and is easily knowable. That’s why healthcare providers ask the question. To recap the terms:

  • 20 weeks “pregnant” = 20 weeks after the first day of the last menstrual period (LMP); used by medical providers to date pregnancies.
  • 20 weeks “gestational age” = usually the same as above, measured since the first day of the last menstrual period; used by medical providers to date pregnancies.
  • 20 weeks “post-fertilization” = may be approximately 22 weeks “pregnant” by the normal method of measuring; used by politicians to promote 20-week abortion bans.

In other words, nobody but politicians uses fertilization as a way of dating a pregnancy.

For the record, a pregnancy does not start at fertilization; implantation must occur for the pregnancy to progress. So why are politicians using “post-fertilization”? For one, politicians may simply have very little understanding of pregnancy. This would not surprise us in the anti-science era of “legitimate rape.” (Though we really wish members of Congress would read .”)

Read cynically, politicians may be deliberately in order to make it read difficult for women to determine whether they are within their legal right to obtain an abortion. For example, a woman told she is “22 weeks pregnant” by a healthcare provider may assume she’s past the cutoff and no longer able to obtain an abortion. In reality, she may be just 20 weeks post-fertilization and still eligible for a short period of time.

Anti-abortion advocates justify 20-week post-fertilization limits based on the widely disputed idea that fetuses at that point. The so-called “Pain-Capable Unborn Child Protection Act” () that the  specifically referred to 20 weeks after fertilization as the cutoff for legal abortion, based on the  idea that fetuses can feel pain at this point. However, a 2005 on the topic concluded that “pain perception probably does not function before the third trimester.”

Similarly, a 2010 report by the Royal College of Obstetricians and Gynaecologists (UK) concluded: “Interpretation of existing data indicates that cortical processing of pain perception, and therefore the ability of the fetus to feel pain, cannot occur before 24 weeks of gestation.”

For all the supposed concern about pain, it’s almost unheard of for anti-abortion activists to discuss the counterbalancing notion of pain, illness, injury and potential death that a woman may face carrying a pregnancy to term — see  in The Nation for read from this perspective.

It’s also important to remember, as , that these bills contain provisions that aim to shut down abortion clinics, including onerous  that are costly and do nothing to increase safety:

Abortion clinics often require doctors from out of state to travel to the clinic, because of the harassment, threats, and even assassinations that local doctors have been subject to? Then we’ll require that every doctor have admitting privileges at a hospital within a certain number of miles, which out-of-state doctors won’t have. And we’ll throw in some rules on how wide your hallways need to be (not kidding), meaning in order to stay open you’d have to do hundreds of thousands of dollars of remodeling. Failing that, we’ll make sure that women who need abortions will have to suffer as much inconvenience, expense, and humiliation as possible.

Ultimately, the GOP’s concern is not so much about minimizing human suffering, but about advancing strategies for to safe, legal abortion.

, Imani Gandy does a  good job explaining the anti-choice litigation strategy, noting in part:

The push for 20-week abortion bans is part of a national strategy implemented by anti-choice advocates to create exactly the sort of legal mess that will force the Supreme Court to reconsider Roe v. Wade and Planned Parenthood v. Casey, and to revisit the viability standard that has served as the constitutional foundation for abortion rights for 40 years.

An analysis by RH Reality Check suggests that the strategy deployed by anti-choicers is deeply subversive. It capitalizes on personal feelings and anti-abortion hostilities by enticing judges and legislatures to abandon empirical science in favor of biased, agenda-driven science or, as it is sometimes called, “.” Proponents of junk science, which has become a cottage industry among anti-abortion advocates, , invent claims about  (), and call into question established medical standards.

The strategy is a smart one, to be sure. Anti-choicers understand that once junk science has been incorporated into legislation, courts are not inclined to question those scientific findings—no matter how agenda-driven they are—and will simply apply the law to those “facts.” In cases when junk science is presented to a court, a judge (or justice) hostile to abortion rights requires only the flimsiest reasoning to ground their legal opinion in fact, even if those “facts” are anything but factual.

As the American Congress of Obstetricians and Gynecologists wrote when addressing political attempts to limit abortion based on ideas about fetal, pain: “.”

Let’s hope the courts think so, too.

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