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Briefing: New law claims a fetus can feel pain

On Tuesday 13 April, the fierce battle over abortion rights in the US took a new twist as Nebraska became the first state to restrict abortion to prevent alleged pain to the fetus.

By using this as the rationale for banning almost all abortions after 20 weeks of pregnancy, the new law (PDF) contradicts the scientific consensus, which holds that fetuses are unlikely to be able to feel pain before 26 weeks. It is also the boldest and most direct challenge yet to the Roe vs Wade ruling of 1973, which gave US women almost unrestricted access to abortions.

So have there been new discoveries in fetal pain research that justify the Nebraska ruling? Or is the law based on a moral judgement? New Scientist answers your questions

What does the new law say?      

It forbids abortions after 20 weeks of pregnancy.

Are there any exceptions?    

A woman pregnant for longer than 20 weeks can still have an abortion to save her life, or if she otherwise faces a "substantial and irreversible physical impairment of a major bodily function", which can't include mental health.

How do these new conditions compare with the rest of the US?

In most other states, abortions are banned only when a fetus is deemed to be old and mature enough to survive outside the womb, typically any time beyond 22 to 23 weeks.

So what's the evidence that 20-week-old fetuses feel pain?

The question of whether and when fetuses feel pain has long been debated by scientists and seized upon by opponents of abortion. The Nebraska law lays out at least four arguments supposedly based on the science of fetal pain – but they are controversial.

Mark Rosen of the University of California, San Francisco, and co-author of a seminal 2005 review on fetal pain rebutted each one in a letter to the Nebraska legislature sent on 30 March. Here is a summary of the claims, followed by Rosen's rebuttals.

Nebraska claim 1: At 20 weeks, an unborn child "has the physical structures necessary to experience pain".

Rosen's rebuttal: The first brain pathways associated with pain perception "are not complete before approximately 29 weeks of gestation", so although fetuses develop brain wiring from about 23 weeks onwards, the connections are not there to enable them to experience pain.

Nebraska claim 2: There is "substantial" evidence that after 20 weeks, fetuses have reflex responses to evade painful stimuli which in children or adults would be perceived as pain.

Rosen's rebuttal: These responses occur involuntarily through reactions by the spinal cord, and like "knee-jerk" responses don't necessarily correspond to pain. The same responses in full-term babies occur when they're touched lightly, for example.

Nebraska claim 3: Fetuses more than 20 weeks old receive anaesthesia if operated on in the womb – this must be because they feel pain.

Rosen's rebuttal: In such operations, the anaesthesia is not given to kill pain but to prevent the fetus from moving, to prevent premature contractions and to stop release of hormones that might otherwise disrupt neurological development.

Nebraska claim 4: There is "substantial" evidence that abortion at and after 20 weeks causes "substantial" pain to an unborn child.

Rosen's rebuttal: The first rebuttal applies again: fetuses don't have the equipment to feel pain before 29 weeks. Also, before most abortions the fetal heart is stopped by a drug – usually digoxin or potassium chloride. The fetus cannot feel pain after that.

So where did the Nebraska legislators find evidence for their claims?

One widely cited researcher is Kanwaljeet Anand of UT Medical Group, the private practice arm of the University of Tennessee Health Science Center in Memphis. Speaking on behalf of the US Department of Justice at a court hearing in 2004 (PDF), he said that in his opinion a fetus subjected to an abortion could feel "severe and excruciating pain" as early as 20 weeks.

Does he stand by that?              

Yes. He told me he believes that pain can be felt before the connections to the cortex are in place; he thinks it is then felt in the subcortex, which matures earlier. His rationale for this is that adults can feel pain in the subcortex even if their sensory cortex is removed. "The cortex is not required for pain perception in the adult, so why use it as a criterion of pain in the fetus?" he asks.

As to when this subcortical pain can be felt, Anand says there's no certainty yet. But he says that preterm babies resuscitated at 22 to 23 weeks show "robust" responses to the insertion of intravenous drips and the fitting of scalp electrodes.

What do other pain specialists think?    

Most agree with Rosen – that fetuses develop the ability to sense pain somewhere between 26 and 29 weeks. In the UK, a 1997 review concluded that fetuses are unlikely to feel pain before 29 weeks. Likewise, a report on abortion in 2007 by the UK House of Commons select committee on science and technology concluded that fetal pain is unlikely earlier than 26 weeks.

Coinciding with Rosen's 2005 review was a paper by David Mellor of Massey University in Palmerston North, New Zealand, and colleagues which concluded from work on sheep that fetuses are unconscious in a sleep-like state throughout pregnancy.

Does anyone agree with Anand?     

Sort of. Vivette Glover of Imperial College London thinks it's possible fetuses feel pain at 20 weeks "but it's far from certain". She backs giving anaesthesia at this stage just in case.

"But this does not justify changing the abortion time limit, where the interests of the mother may be much more important than those of the fetus, and the two have to be balanced," she adds.

Indeed, Maria Fitzgerald of University College London, co-author of a report on fetal pain in 1997 by the British Royal College of Obstetricians and Gynaecologists, calls the Nebraska law "completely irrational". She points out that even if fetuses could feel pain at 20 weeks, "it is irrelevant because if you wanted you could make sure there was adequate analgesia for an abortion".

Is there reason to think the law is politically motivated?

According to opponents of the law, it's no accident this is all happening in Nebraska, because that's where LeRoy Carhart, a surgeon willing to do late-term abortions, practises. "The goal behind the legislation is quite transparent, namely, to shut down late-term abortion provider Carhart," says Rosen. He suggests that Carhart might contest the bill in court and that the case could eventually make its way to the Supreme Court, where it could lead to a new ruling that overturns Roe vs Wade.

What will happen next?         

A spokeswoman from the pro-choice Guttmacher Institute in New York says that such a case would first have to be brought in a district court. If Carhart lost, the case would have to be accepted by a court of appeals before being put before the Supreme Court. She says that other states would probably hold fire on introducing similar legislation until these cases have run their course.

Journal reference: Journal of the American Medical Association, vol 294, p 947


A painful process? (Image: Gary Bistram/Rex Features)



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