Dr. Aaron Caughey is the chairman of the Department of Obstetrics and Gynecology at Oregon Health and Sciences University, director of its Center for Women’s Health, and a researcher with an interest in diabetes in pregnancy. He recently addressed the pushing question at the Birth World Congress in Chicago.
Q: What attracted you to obstetrics?
A: I’m a labour-floor junkie. As a third-year medical student doing an obstetrics rotation, it was immediate for me, like a crush. The process of birth, the intensity of the experience, the potential for it to be many people’s best days mixed with a small percentage of people’s worst days, and the challenge of how to make the outcomes better—it’s extremely compelling.
Q: Let’s start with a brief refresher course on labour.
A: The first stage of labour goes from the beginning of contractions until a woman’s cervix is completely dilated, the second stage is from the beginning of when she starts pushing until the baby delivers, and the third stage is from the delivery of the baby until the delivery of the placenta. The first stage of labour is divided into two phases: latent and active. The latent phase was really defined by Emanuel Friedman in the 1950s and 1960s.
Q: But the Friedman curve continues to influence guidelines about the length of time a woman should labour before medical intervention is indicated, right?
A: Right. Let’s say a woman has dilated to six centimetres, time is passing, and there’s no change. The older research indicates you should wait at most for two hours, then move on to a Caesarean or forceps delivery. However, the more recent work of OB/GYN Dwight Rouse and others shows that for women who are in spontaneous labour, if you just wait another two hours, 60 per cent will deliver vaginally.
Q: But Friedman’s research is what you’d be taught in medical school, right?
A: Most textbooks probably only mention the Friedman curve.
Q: Do midwives follow the two-hour rule?
A: Some midwives, depending on how they’re trained, can be pretty adherent to strict guidelines like the two-hour rule. But others, like someone who’s breaking from traditional obstetrical care and might even offer home birth, might let a woman who’d reached six or even eight centimetres stall out for a matter of hours. They’re just much more patient.
Q: Was Friedman’s research sloppy?
A: No. This was years before the personal computer. The sample sizes were relatively small because data analysis by hand is quite challenging. Some of the biostatistics we can do today just weren’t possible. But in terms of the study design, his methods are right on and anyone doing labour curves today uses them.
Q: Why do the newer curves look so different from Friedman’s, then?
A: His population was mostly Caucasian women in spontaneous labour. The populations we take care of today are very different. The rate of obesity has doubled in the last 15 years, and obese women tend to have bigger babies and tend to be in labour longer. The other thing that’s changed is the use of the epidural. In Friedman’s studies, the rate of use was about eight per cent, but on most labour floors today it’s between 70 and 90 per cent. The epidural slows labour down. Many times, in the first stage, after an epidural you’ll see a decrease in the rate of contractions. In the second stage it’s blockading your nerves, so you have less motor strength and can’t push as hard.
Q: You’re an advocate of letting women stall even after they’re fully dilated, and say there’s no big rush to push. Why not?
A: This is called “delayed pushing” or “labouring down.” Before epidurals, this probably wouldn’t have occurred to anyone to do, because once a woman is fully dilated and the baby’s head starts moving down in the pelvis there’s enormous pressure on the pelvic nerves and that gives the woman an enormous urge to push. But with an epidural, you’re blocking not only the motor connection, the ability to push, but you’re also blocking the sensation, the pain. And in that case, women don’t feel that strong urge, they can wait.
Q: But why wait?
A: We know the second stage takes longer with an epidural, so now you have women pushing so long, three or four hours even with totally normal births, that they get tired. If you’re in a clinical setting where three hours of pushing is used as an upper bound—at three hours, it’s called a prolonged second stage of labour—and you’ve barely been able to move the baby because you’re weak from the epidural, someone is going to say, “Oh gosh, the baby hasn’t come down, it’s time for your forceps delivery or a C-section.” The idea of labouring down is to say, “If you want to allot three hours for pushing, then why don’t we let the uterus do some work for an hour or so, get the baby down a little more, then the mom can start to push—and she’s less likely to need a C-section.”
Q: That just sounds like common sense.
A: Exactly. I’ve been doing it since the mid-’90s. In the biggest and best-known randomized study—the lead author, Bill Fraser, is Canadian—900 women pushed early and 900 waited for a couple of hours. In the delayed pushing group, there were less of what they characterized as difficult deliveries, which included C-sections and mid-pelvic or higher-up forceps deliveries. The women pushed on average about 68 minutes in the delayed arm, versus 110 minutes in the other arm. However, the total length of the second stage of labour was about an hour longer because of the delay.
Q: Were their babies just as healthy?
A: The vast majority of babies are just fine. However, in the delayed arm, in a very small percentage of cases, there was more maternal fever, and it does seem that the babies of women who have maternal fever are at risk for some bad long-term outcomes. The second thing is that a very small percentage of the babies of women who delayed pushing had slightly lower pH or acid levels. When pH is low, you start worrying about injuries to the baby’s brain.
Q: So what would you advise a woman who’s in labour, not progressing after two hours, whose doctor is urging a C-section?
A: She should hand Dwight Rouse’s paper to her doctor, and say, “No, let’s make sure we have the oxytocin at the right levels, and we should wait at least four hours.”
Q: Is a C-section really such a big deal?
A: It is major abdominal surgery, and what’s not discussed enough with women is what it means for future pregnancies. Many hospitals won’t even let you try to deliver vaginally next time.
Q: Is there an incentive for a physician to order a C-section even if it’s the woman’s first pregnancy?
A: The physician doesn’t make that much more for a Caesarean delivery, about 10 per cent more in the U.S. For the physician, the main incentive is related to time and convenience. If I’m on call all weekend, and I’ve got somebody in labour who’s been six centimetres dilated for a couple of hours and it’s 5 p.m. on a Friday—well, if I do a C-section now, I might get to leave the hospital to see my family. If I give her two more hours, and she dilates further, that still doesn’t mean she’s ready to deliver. It could be midnight before she’s completely dilated, and then she could push for three or four hours, and at the end, I’m paid about the same as if I’d just done the C-section 12 hours earlier.
Q: Today, about 33 per cent of births in the U.S. are Caesarean deliveries, and you co-authored a study that says that if current trends continue, by 2020, 56 per cent of births will be by C-section. Is the problem that doctors just can’t be bothered to wait?
A: My gut is that the biggest contributor is the legal environment. If something goes wrong and you get sued, you’re going to spend weeks to months in a courtroom—and there’s all that lost revenue to your practice while you’re sitting there—being described by the plaintiff’s attorney as one of the most evil people to walk the earth since Hitler. Adam Smith described incentives in economics as the invisible hand—they’re in your subconscious. I think if you polled 100 honest physicians, none of them would say, “My incentive was to get home at five.” But it’s there, it’s the natural incentive. And I think they’re trying to prevent bad things happening to their patients. The reasoning is, “As soon as you’re slightly abnormal [deviating from the Friedman labour curve], I think you’re at risk for shoulder dystocia or some other bad outcome for your baby, so I’m going to do a C-section. Why take any chances?”
Q: From a health standpoint, what’s wrong with a C-section?
A: You’re more likely to have a hemorrhage, or a postpartum infection. Someone with a prior C-section has a higher risk of a placenta previa or a placenta accreta, which is where the placenta is either covering the cervix or eating into the wall of the uterus, so you may require a hysterectomy. And you’re more likely to die if you have a C-section.
Q: How much more likely?
A: The chances are about one in 100,000. What’s way more likely is that you’re stuck having more C-sections in the future.