What I'd like to look at first his how certain we are of gestational age in the first place.
This article addresses errors in estimating gestational age: "The accuracy of ultrasound in predicting gestational age gets worse as the pregnancy advances. By 20 weeks, ultrasound is accurate only to within plus or minus two weeks, and by the third trimester, its accuracy falls to plus or minus 3 weeks."
Ultrasound is the most common method of estimating gestational age in abortion practice. Many women are going in for late abortions because they'd lost track of their cycles and weren't sure they were pregnant at all, so the LNMP method of dating is lost with these women. The doctors are having to rely almost entirely on ultrasound.
Of course, the errors can be even greater. Here are some cases of abortion doctors miscalculating gestation age: a supposedly 21-week baby who turned out to be 30 weeks, a supposedly 11-week baby that turned out to be 27 weeks, a baby that was believed to be about 12 weeks and turned out to be 28 weeks, and a supposedly 6-week baby that turned out to be 26 weeks. I'll recognize, however, that these are unusual screw-ups. I'll just focus on being within the margin of error for a doctor who is taking reasonable care.
Now let's take a look at preemie survival rates. When I originally wrote about this topic, I found preemie survival rates here:
- 22 weeks: 0-10% survival rate
- 23 weeks: 10-35% survival rate
- 24 weeks: 40-70% survival rate
- 25 weeks: 50-80% survival rate
- 26 weeks: 80-90% survival rate
- 27 weeks: greater than 90% survival rate
So now let's take ultrasound margins of error into account, along with the new information about survival for babies that are actually cared for rather than just keeping them comfortable and waiting for them to die.
Even with a properly performed ultrasound, a 20 week abortion can actually mean the death of a 22-week child who had a 23% chance of survival. Abortion facilities are willing to do abortions far past 20 weeks.
Some facilities openly advertise elective abortions to 26 weeks -- babies that have an 80-90% chance of survival, and who may actually be three weeks older than estimated. They might be as old as 29 weeks, with a greater than 90% chance of survival. Of course, of you are deft with the in-utero lethal injection, or if you wrap any live-born infants in a towel and stick them in a closet, as the abortion lobby insists is appropriate, they have a 0% chance of survival.